Morphometry, topography and arterial supply of the thyroid gland in brazilian shorthair cat

Thyroid gland diseases are the most common endocrinopathies in feline practice. Diagnosis and surgical treatment must base on solid anatomical knowledge about the gland size, localization, and blood supply. However, some textbooks provide a general anatomical description of the thyroid gland of domestic carnivores. Thus, specific details of the feline gland are missing. The present study aimed to investigate the dimensions, topography, and arterial supply of the thyroid gland in Brazilian shorthair cats and, therefore, provide additional data to diagnose and treat feline thyroid diseases. Thirty Brazilian shorthair cats formalin-fixed cadavers (15 male and 15 female) were injected with red-stained latex solution by a canula in the thoracic aorta. The necropsy unit of the Rural Federal University of Rio de Janeiro donated the specimens. The study included only adult animals with no history of thyroid disease. After the fixation period, the cadavers were dissected to investigate the measurements (length, width at cranial and caudal poles, and thickness), topography, and in situ arterial supply of the thyroid lobes. The mean measurements of the length, cranial pole width, caudal pole width, and thickness in the right lobe were 19.39 ± 3.10 mm, 5.36 ± 1.40 mm, 3.67 ± 0.93 mm, and 1.30 ± 0.29 mm, respectively; and 20.29 ± 3.35 mm, 4.85 ± 1.58 mm, 3.88 ± 0.91 mm, 1.64 ± 0.65 mm in the left lobe, respectively. There were no statistical differences (P > 0.05) in the comparison of the measures between sexes or antimers (sides). Pearson's linear correlation detected a positive, moderate (r = 0.55), and significant (P < 0.05) correlation between the right and left lobe lengths. In 70% of the cats, both left and right lobes had the cranial poles located at the same level. Typically, the lobes extended between the first to the eighth tracheal ring. However, the cranial pole of some lobes located as cranially as the cricoid cartilage level, and the caudal pole as caudally as the 12th tracheal ring. Fifty-six percent of the cats had a ventrally located isthmus. In all the sampling, one single thyroid artery emerged as a branch of the common carotid artery and provided branches directly to the thyroid lobe, isthmus and the adjacent muscles and esophagus. Besides establishing average dimensions of normal thyroid lobes in Brazilian shorthair cats, this study detected no significant difference between the average measurements of right and left lobes. Also, a positive linear correlation between the length and width of the right and left lobes became evident. Therefore, the practitioner must consider suspicious any length asymmetry between right and left thyroid lobes until further endocrine test proves otherwise. Most of the cats had the right and left thyroid lobe positioned at the same transversal level; however, positional asymmetries are not uncommon. Unlike dogs, Brazilian shorthair cats have only a single artery to supply each lobe: the thyroid artery. In a feline thyroidectomy, the surgeon must avoid blindly ligating the thyroid artery since this vessel also provided numerous branches to adjacent muscles and esophagus. In a bilateral thyroidectomy, the ventral region between lobes should be thoroughly inspected for the common presence of an isthmus. Sometimes, the surgeon may need to extend the incision caudally beyond the 12th tracheal ring level to visualize the gland tissue entirely.(AU)

Morfometría y vascularización de la glándula tiroides en conejo (Oryctolagus cuniculus) / Morphometry and vascularization of the thyroid glands in rabbits (Oryctolagus cuniculus)

Las glándulas tiroides consisten en dos partes denominadas lobos que se encuentran en ambos lados de la laringe. El objetivo de este estudio fue caracterizar las medidas, topografía y vascularización de la glándula tiroides de conejos Nueva Zelanda. Las disecciones anatómicas se realizaron en 36 cadáveres adultos, 17 machos y 19 hembras, con masa corporal media de 2,5 kg y longitud cara-sacral media de 40 cm. Los cadáveres fueron obtenidos del sector de necropsia de la Universidad. Los especímenes tuvieron la arteria aorta torácica canalada, por la cual se inyectó solución de formaldehído al 10 %, seguida de látex coloreado. En los machos, el lobo izquierdo de la glándula tiroidea midió 1,40 x 0,40 x 0,01 cm y el derecho 1,36 x 0,56 x 0,01 cm; en las hembras, el lobo izquierdo midió 1,50 x 0,49 x 0,01 cm y el derecho 1,37 x 0,48 x 0,01cm. No hubo diferencia significativa (p> 0,05) entre las medias de las medidas entre machos y hembras, pero la extensión del lóbulo izquierdo de las hembras y la anchura del lóbulo derecho de los machos fueran significativamente mayores (p <0,05). La extremidad craneal de los lobos tiroideos se encontraba al nivel del cartílago cricoide en casi todos los especímenes. El extremo caudal presentó topografía más variable, desde el tercer hasta el décimo anillo traqueal, habiendo predominado al nivel del quinto anillo. Invariablemente, la irrigación arterial fue determinada por las arterias tiroideas izquierda y derecha, originadas de la arteria carótida común. Las anastomosis entre las arterias tiroideas fueron comunes. La constancia en las dimensiones y irrigación de la glándula tiroidea puede ser ventajosa en la elección del Coelho como modelo experimental para el estudio de esta glándula.

The thyroid glands consist of two parts called lobes located on both sides of the larynx. The aim of this study was to characterize the measures, topography and arterial irrigation of New Zealand´s rabbits thyroid glands. The anatomical dissections were performed in 36 adult cadavers, 17 males and 19 females, with a mean body mass of 2.5 kg and a mean cranium-sacral length of 40 cm. The specimens were obtained from the necropsy unit of the University. The cadavers had the thoracic aorta artery cannulated, through which 10 % formaldehyde solution was injected, followed by injection colored latex. In males, the left lobe of the thyroid gland measured 1.40x0.40x0.01cm and the right 1.36x0.56x0.01cm; in females, the left lobe measured 1.50x0.49x0.01cm and the right one was 1.37x0.48x0.01cm. There was no significant difference (p> 0.05) between the means of the measurements between males and females, but the left lobe length of the females and the right lobe width of the males were significantly higher (p <0.05). The cranial extremity of the thyroid lobes was at the level of the cricoid cartilage in almost all specimens. The caudal end showed more variable topography, from the third to the tenth tracheal ring in few specimens, but predominated at the level of the fifth ring. Invariably, arterial irrigation was determined by the left and right thyroid arteries, originating from the common carotid artery. Anastomoses between the thyroid arteries were common. The constancy in dimensions and irrigation of the thyroid gland may be advantageous in choosing the rabbit as an experimental model for the study of this gland.

Ultrasonographic features of the normal thyroid gland in adult horses / Características ultrassonográficas da glândula tireoide hígida em equinos adultos

Few reports have been published regarding the use of ultrasonography as a method of evaluating the normal thyroid gland in horses. For these reasons, this study aimed at determining reliably of the thyroid measurements from the comparison between the left and right thyroid lobes, as well as assessing the contour, format, echotexture and echogenicity of the healthy thyroid by mode-B ultrasonography. Additionally, the equine thyroid vascularization was quali-quantitatively characterized the by Doppler. The sample size initially was determined by the animal selection with advanced age and without volume increase in the neck proximal region. Finally, eleven horses were selected by laboratory test, search of thyroid neoformations by ultrasonography and cytology thyroid. Next, these animals were submitted to thyroid lobes ultrasonographic evaluation. Excellent reproducibility was observed for all measurements obtained. Among the comparisons made between the quantitative parameters of the left and right lobes, it was observed that there was only difference between their respective lengths. Qualitatively, there was a significant variation between the lobes elliptical format in the longitudinal plane of some glands, which oscillated between a rounded and flattened conformation. Thus, we can conclude that the difference between the lobes format of some thyroids can be explained by the significant difference observed between the length of the left and right lobes. Additionally, it was verified that there was no difference between the Doppler quantitative parameters. Therefore, we may suggest that unilateral analysis of the cranial thyroid artery by spectral Doppler can be used to evaluate equine thyroid diffuse disorders.(AU)

Poucas análises foram publicadas com relação ao uso da ultrassonografia como método de avaliação da glândula tireoide hígida em equinos. Alguns trabalhos incluem a determinação das dimensões e características do parênquima. Por essas razões, este estudo teve como objetivo determinar com segurança as medidas tireoidianas a partir da comparação entre o lobo tireoidiano esquerdo e direito, bem como avaliar os contornos, formato, ecotextura e ecogenicidade das glândulas tireoides hígidas pela ultrassonografia em modo B. Além disso, a vascularização da tireoide equina foi caracterizada quali-quantitativamente pela ferramenta Doppler. O tamanho da amostra inicialmente foi determinado pela seleção dos animais com idade avançada e sem aumento de volume na região proximal do pescoço. Por fim, onze equinos foram selecionados por meio de exame laboratorial, pesquisa de neoformações tireoidianas por ultrassonografia e citologia da tireoide. Em seguida, estes animais foram submetidos à avaliação de lobos tireoidianos por ultrassonografia. Observou-se excelente reprodutibilidade em relação a todas as medidas deste estudo. Foram observadas diferenças qualitativas entre os lobos tireoidianos direito e esquerdo. Assim, podemos concluir que tais diferenças entre o formato dos lobos tireoidianos podem ser explicadas pela diferença significativa e/ou tendência observada no parâmetro comprimento entre os respectivos lobos. Além disso, não foi encontrada diferença significativa entre os valores da artéria tireoidiana cranial esquerda em relação aos obtidos na artéria tireoidiana cranial direita, sugerindo que a análise dos valores espectrais do Doppler de uma das artérias tireoidianas craniais possa ser utilizada como método de avaliação de distúrbios difusos da tireoide equina.(AU)

O tubérculo de Zuckerkandl pode auxiliar na localização do nervo laríngeo inferior durante tireoidectomias? / Can the Zuckerkandl tubercle assist in the location of the inferior laryngeal nerve during thyroidectomies?

RESUMO Objetivo: avaliar se a projeção lateral da glândula tireoide, chamada tubérculo de Zuckerkandl (TZ), pode auxiliar o cirurgião na identificação do nervo laríngeo inferior durante a tireoidectomia convencional aberta. Métodos: estudo prospectivo de 51 pacientes submetidos à tireoidectomia, com um total de 100 lobos tireoidianos ressecados, e observação da presença ou não do TZ em dimensões suficientes para ser identificado sem magnificação de imagem, suas dimensões de base e altura, sua localização na glândula e sua relação anatômica com o nervo laríngeo inferior. Resultados: o TZ estava presente em 68 dos 100 lobos de tireoide analisados (68%). A dimensão média da base foi 6,7mm no lado direito e 7,1mm no lado esquerdo, e a altura média foi 5,7mm no lado direito e 6,1mm no lado esquerdo. Na maioria dos lobos estudados, o tubérculo tinha altura mínima de 5mm (55,9%) sem diferença significativa entre o lobo direito e esquerdo da glândula tireoide. Durante a cirurgia, 100% dos TZ identificados estavam anteriores ao nervo laríngeo inferior, imediatamente abaixo da entrada do nervo na laringe. Conclusão: o TZ é bastante frequente e em dimensões suficientes para ser usado como referência anatômica na localização intraoperatória do nervo laríngeo inferior, próximo à sua entrada na laringe, junto com as demais referências anatômicas.

ABSTRACT Objective: to evaluate whether the lateral projection of the thyroid gland, called Zuckerkandl's tubercle (ZT), can assist the surgeon in identifying the inferior laryngeal nerve during conventional open thyroidectomy. Methods: we conducted a prospective study with 51 patients submitted to thyroidectomy, with a total of 100 resected thyroid lobes, and observed the presence or absence of ZT in sufficient dimensions to be identified without image magnification, its base and height, its location in the gland, and its anatomical relationship with the inferior laryngeal nerve. Results: ZT was present in 68 of the 100 thyroid lobes analyzed (68%). The mean base was 6.7mm on the right side and 7.1mm on the left side, and the average height was 5.7mm on the right side and 6.1mm on the left side. In most of the lobes studied, the tubercle had a minimum height of 5mm (55.9%), with no significant difference between the right and left lobes of the thyroid gland. During surgery, 100% of the identified ZTs were anterior to the inferior laryngeal nerve, just below the nerve entry in the larynx. Conclusion: the ZT is a quite frequent entity and large enough to serve as an intraoperative anatomical reference for the inferior laryngeal nerve, next to its entry in the larynx, along with other anatomical references.

Origin of superior thyroid artery: under the surgeon's knife / Origem da artéria tireoidea superior: sob o bisturi do cirurgião

The major arterial supply to the thyroid gland is from the superior and inferior thyroid arteries, arising from the external carotid artery and the thyrocervical trunk respectively. The external laryngeal nerve runs in close proximity to the origin of the superior thyroid artery in relation to the thyroid gland. The superior thyroid artery is clinically important in head and neck surgeries. Objectives: To locate the origin of the superior thyroid artery, because wide variability is reported. To provide knowledge of possible variations in its origin, because it is important for surgical procedures in the neck. Methods: The origin of the superior thyroid artery was studied by dissecting sixty adult human hemineck specimens from donated cadavers in a Department of Anatomy. Results: The highest incidence observed was origin of the superior thyroid artery from the external carotid artery (88.33%), whereas origin from the common carotid bifurcation only occurred in 8.33%. However, in 3.33% of cases, the superior thyroid artery originated from the common carotid artery and in a single case, the external laryngeal nerve did not cross the stem of the superior thyroid artery at all, but ran ventral and parallel to the artery. Conclusions: It is important to rule out anomalous origin of superior thyroid artery and verify its relationship to the external laryngeal nerve prior to ligation of the artery in thyroid surgeries, in order to prevent iatrogenic injuries. Moreover, because anomalous origins of the superior thyroid artery are only anatomic variants, thorough knowledge of these is decisive for head and neck surgeries

O suprimento arterial principal para a glândula tireoide provém das artérias tireoideas superior e inferior, que têm origem na artéria carótida externa e no tronco tireocervical, respectivamente. O nervo laríngeo externo faz um percurso bem próximo à origem da artéria tireoidea superior em relação à glândula tireoide. A artéria tireoidea superior é clinicamente importante em cirurgias da cabeça e do pescoço. Objetivos: Localizar a origem da artéria tireoidea superior, considerando a ampla variabilidade descrita na literatura; e oferecer informações sobre possíveis variações em sua origem, devido à importância disso para procedimentos cirúrgicos realizados no pescoço. Métodos: A origem da artéria tireoidea superior foi estudada dissecando-se 60 espécimes de hemipescoço adulto de cadáveres humanos doados ao Departamento de Anatomia. Resultados: A maior incidência observada foi da artéria tireoidea superior com origem na artéria carótida externa (88,33%), enquanto a origem na bifurcação da artéria carótida comum ocorreu em apenas 8,33%. No entanto, em 3,33% dos casos, a artéria tireoidea superior teve origem na artéria carótida comum, e em um único caso, o nervo laríngeo externo não cruzou o tronco da artéria tireoidea superior em nenhum momento, embora tenha cursado ventral e paralelamente a essa artéria. Conclusões: É importante descartar origem anômala da artéria tireoidea superior e confirmar sua relação com o nervo laríngeo externo antes da ligadura da artéria em cirurgias da tireoide, para evitar efeitos iatrogênicos. Além disso, como origens anômalas da artéria tireoidea superior são apenas variantes anatômicas, o conhecimento detalhado dessas variações é decisivo para cirurgias da cabeça e do pescoço

Microcalcificaciones y focos ecogénicos puntiformes, ¿qué tan bien sabemos lo que estamos viendo? / Microcalcifications and punctate echogenic foci, how well do we know what we are seeing?

Resumen: La presencia de microcalcificaciones en nódulos tiroideos es un signo muy específico de malignidad, al corresponder a cuerpos de Psammoma. No existen suficientes estudios que demuestren una correlación entre su presencia histológica y su aspecto ecográfico real. Materiales y Métodos: Se seleccionaron todos los nódulos con tamaño mayor a 3 cm puncionados en el Hospital Clínico Universidad Católica entre los años 2010-2015 y se clasificó el aspecto ecográfico según la presencia de 3 tipos de focos ecogénicos con una definición más estricta a lo usual. Se correlacionó lo anterior con hallazgos en biopsias. Resultados: 44 nódulos correspondieron a cáncer papilar de tiroides. Hubo relación estadísticamente significativa entre una nueva definición ecográfica de las microcalcificaciones (focos ecogénicos puntiformes) y la presencia histológica de cuerpos de psamomma. Discusión: Habría una buena correlación entre una definición más estricta y la presencia real de microcalcificaciones en histología, mejorando la alta tasa de sobrediagnóstico advertido recientemente por algunos autores.

Abstract: The presence of microcalcifications in thyroid nodules is a very specific sign of malignancy, as it corresponds to Psammoma bodies. There are not enough studies that demonstrate a correlation between their histological presence and their actual ultrasound appearance. Materials and Methods: All nodules larger than 3 cm punctured at the Universidad Católica Clinical Hospital between 2010-2015 were selected, and the sonographic appearance was classified according to the presence of 3 types of echogenic foci according to a stricter definition than usual. The above was correlated with findings in biopsies. Results: 44 nodules corresponded to papillary thyroid cancer. There was a statistically significant relationship between a new ultrasound definition of the microcalcifications (punctate echogenic foci) and the histological presence of psamomma bodies. Discussion: There would be a good correlation between a stricter definition and the actual presence of microcalcifications in histology, improving the high rate of over diagnosis recently noticed by some authors.

Which method is gold standard for determination of thyroid volume? / ¿Cual es el método gold standard para determinar el volumen de la glándula tiroides?

Change of the thyroid gland volume is often the symptom of most common pathological conditions some thyroid diseases. The exact calculation for the thyroid volume is very important for the assessment and management of thyroid disorders. The volume of thyroid gland, using computed tomography (CT), ultrasound (USG) and magnetic resonance imaging (MRI) has been accessed in few studies published; however a gold standard method has not yet been determined. The purpose of this study was to estimate the volume of normal thyroid gland to define an optimal correction factor therefore was to compare different techniques using the CT. We used computed tomography images obtained from 8 cadavers (2 females, 6 males) to calculate the thyroid volumes. In the present study, the actual thyroid volumes were measured using the water-displacement method as a gold standard, point-counting as a stereology, and ellipsoid methods. Mean squared errors and correction factors were calculated and modeled for each model to find an optimal correction factor and from 0.450 to 0.600 in steps of 0.001 separately for thyroid volume estimation. The average volume of the thyroid glands were 14.58 ± 9.84, 15.28 ± 9.38, and 14.97 ± 8.35 cm3 by fluid displacement, stereology and ellipsoid formula, respectively. No significant difference was found among the methods (P >0.05). The results of this study suggested that the volume of thyroid gland can be measured on CT scans stereologically for diagnosis, as will as provide reliable measure of thyroid volume, management and follow-up of thyroid diseases and for preoperative planning.

El cambio de volumen de la glándula tiroides es a menudo el síntoma de las condiciones patológicas más comunes de algunas enfermedades de dicha glándula. El cálculo exacto del volumen tiroideo es muy importante para la evaluación y el tratamiento de los trastornos tiroideos. El volumen de la glándula tiroides, utilizando la tomografía computarizada (TC), el ultrasonido (USG) y la resonancia magnética (RM) ha sido presentados en varias publicaciones. Sin embargo, aún no se ha determinado un gold standard. El propósito de este estudio fue estimar el volumen de la glándula tiroides normal para definir un factor de corrección óptimo, por lo que se compararon diferentes técnicas utilizando TC. Para calcular los volúmenes tiroideos se utilizaron imágenes de tomografía computarizada obtenidas de 8 cadáveres (dos mujeres y seis hombres). En el presente estudio, los volúmenes reales de la glándula tiroides se midieron utilizando como gold standard los métodos esterológicos de desplazamiento de agua y conteo de puntos y el método volumétrico elipsoide. Se calcularon y modelaron los errores cuadráticos medios y los factores de corrección para cada modelo con el objetivo de encontrar un factor de corrección óptimo y de 0,450 a 0,600 en pasos de 0,001 por separado para la estimación del volumen tiroideo. El volumen medio de las glándulas tiroides fue de 14,58 ± 9,84, 15,28 ± 9,38 y 14,97 ± 8,35 cm3 calculados por desplazamiento de fluido, estereología y fórmula elipsoide, respectivamente. No se encontró diferencia significativa entre los métodos (P>0,05). Los resultados de este estudio sugieren que el volumen de la glándula tiroides puede ser medido estereológicamente por TC, estableciéndose como una medida fiable del volumen tiroideo, para el diagnóstico, manejo y seguimiento de las enfermedades tiroideas y la planificación preoperatoria.

Ultrasonographic assessment of thyroid volume in oldest-old individuals

ABSTRACT Objective The aim of this study was to describe the relationship between thyroid volume and age, gender, anthropometric characteristics, and echogenicity in oldest-old subjects in an iodine-sufficient area. Subjects and methods The study included 81 independent elderly individuals aged ≥ 80 years (65 [80.2%] women). We determined these individuals' anthropometric characteristics, body mass index (BMI), and lean body mass, as well as thyroid volume and echogenicity by ultrasonography. Results We observed that octogenarians and nonagenarians had different profiles of thyroid echogenicity. The volume of the thyroid was smaller in nonagenarians than octogenarians (p = 0.012, r = 0.176), and subjects aged 80-89 years had more often hypoechoic glands than those aged ≥ 90 years (p = 0.01 versus 0.602). Conclusion The identification of ultrasonographic differences in oldest-old individuals will contribute to establishing preclinical markers, such as echogenicity, to identify individuals at risk of developing autoimmune thyroid disease. Future prospective studies should identify if 80-89-year-old individuals with hypoechoic glands progress to hypothyroidism, and if the absence of changes in echogenicity (i.e. a normal thyroid parenchyma) would have a positive impact on longevity among nonagenarians.

Genetic and environmental influence on thyroid gland volume and thickness of thyroid isthmus: a twin study

Objectives Decreased thyroid volume has been related to increased prevalence of thyroid cancer. Subjects and methods One hundred and fourteen Hungarian adult twin pairs (69 monozygotic, 45 dizygotic) with or without known thyroid disorders underwent thyroid ultrasound. Thickness of the thyroid isthmus was measured at the thickest portion of the gland in the midline using electronic calipers at the time of scanning. Volume of the thyroid lobe was computed according to the following formula: thyroid height*width*depth*correction factor (0.63). Results Age-, sex-, body mass index- and smoking-adjusted heritability of the thickness of thyroid isthmus was 50% (95% confidence interval [CI], 35 to 66%). Neither left nor right thyroid volume showed additive genetic effects, but shared environments were 68% (95% CI, 48 to 80%) and 79% (95% CI, 72 to 87%), respectively. Magnitudes of monozygotic and dizygotic co-twin correlations were not substantially impacted by the correction of covariates of body mass index and smoking. Unshared environmental effects showed a moderate influence on dependent parameters (24-50%). Conclusions Our analysis support that familial factors are important for thyroid measures in a general twin population. A larger sample size is needed to show whether this is because of common environmental (e.g. intrauterine effects, regional nutrition habits, iodine supply) or genetic effects.

Ultrasonography-Based Thyroidal and Perithyroidal Anatomy and Its Clinical Significance

Ultrasonography (US)-guided procedures such as ethanol ablation, radiofrequency ablation, laser ablation, selective nerve block, and core needle biopsy have been widely applied in the diagnosis and management of thyroid and neck lesions. For a safe and effective US-guided procedure, knowledge of neck anatomy, particularly that of the nerves, vessels, and other critical structures, is essential. However, most previous reports evaluated neck anatomy based on cadavers, computed tomography, or magnetic resonance imaging rather than US. Therefore, the aim of this article was to elucidate US-based thyroidal and perithyroidal anatomy, as well as its clinical significance in the use of prevention techniques for complications during the US-guided procedures. Knowledge of these areas may be helpful for maximizing the efficacy and minimizing the complications of US-guided procedures for the thyroid and other neck lesions.

Agenesis of Isthmus of thyroid gland with presence of pyramidal lobe and levator glandulae thyroideae.

A wide range of morphological and developmental variations of thyroid gland like hypoplasia, ectopic thyroid tissue, hemiagenesis or agenesis of thyroid gland has been reported. Out of these agenesis of the thyroid isthmus is a very rare congenital anomaly. Thyroid isthmus agenesis does not manifest clinical symptoms, and it can be confused with other thyroid pathologies. Also the presence of levator glandulae thyroideae and its anatomical variations gain importance in the pathologies which are related to thyroid gland and their treatment modalities. We hereby, report the absence of isthmus and presence of levator glandulae thyroideae and pyramidal lobe in a middle aged male cadaver. The present case report is an attempt to highlight the implications of variation of thyroid gland from diagnostic, phylogenetic and functional perspectives.

Thyroid Ultrasonography: Pitfalls and Techniques

Thyroid ultrasonography (US) plays a key role in the diagnosis and management of thyroid-related diseases. The aim of this article was to illustrate various pitfalls that can occur in utilizing thyroid US and techniques to prevent them. In this article, we present cases demonstrating the common pitfalls associated with US equipment, performance, normal thyroid structures, misinterpretations, and surrounding structures. Knowledge of these areas is essential to avoid misdiagnosis or improper disease management.

Histological and immunohistochemical study of the thyroid gland of the broad-snouted caiman (Caiman latirostris) / Estudo histológico e imuno-histoquímico da glândula tireoide do jacaré do papo-amarelo (Caiman latirostris)

The broad-snouted caiman, Caiman latirostris, is widely distributed in countries of South America. In Brazil it is considered an endangered species because of natural habitat destruction and illegal hunting. In reptiles, the thyroid gland plays an integral part in ecdysis, reproduction, tail regeneration, growth, endocrine function and metabolism rate. The aim of the present study was to characterize the thyroid gland morphology of C. latirostris, based on histochemical and immunohistochemical techniques. The thyroid glands were fixed in Bouin's fluid and serial cross sections were stained with hematoxylin-eosin, Mallory's trichrome, periodic acid-Schiff (PAS) and Alcian blue (AB pH 1.5 and 2.5). The immunohistochemical technique for 5-HT-IR cells was used. The thyroid gland has a dense irregular connective tissue forms a capsule enveloping the gland. There are several follicular acini of varying size lined by simple cuboidal or columnar epithelium in the thyroid gland. The follicles are connected by interfollicular connective tissue which contains blood vessels. We observed the presence of lymph nodes around the entire gland. There was a positive PAS reaction and negative AB reaction in the colloid. 5-HT-IR cells were detected around the follicle cells. No striking morphological differences were observed between C. latirostris and other domesticated mammals.

O jacaré do papo-amarelo, Caiman latirostris, é amplamente distribuído nos países da America do Sul. No Brasil este é considerado uma espécie em extinção pela destruição de seu habitat natural e caça ilegal. Em répteis, a glândula tireoide desempenha um papel fundamental na ecdise, reprodução, regeneração da cauda, crescimento, função endócrina e na taxa de metabolismo. O objetivo do estudo foi caracterizar a morfologia da glândula tireoide de C. latirostris, com base em técnicas de histoquímica e imuno-histoquímica. As tireoides foram fixadas em Bouin e seções transversais corados com hematoxilina-eosina, Tricrômico de Mallory, ácido periódico de Schiff (PAS) e Alcian blue (AB pH 1,5 e 2,5). A técnica de imuno-histoquímica para detecção de células imunoreativas a 5-HT foi utilizada. A glândula tireoide possui uma cápsula de tecido conjuntivo denso não modelado. Há numerosos ácinos foliculares de tamanho variáveis revestidos por epitélio cúbico ou cilíndrico simples. Entre os folículos observa-se o tecido conjuntivo ricamente vascularizado. Observamos a presença de linfonodos ao redor de toda a glândula. No coloide observou-se uma reação PAS positiva e AB negativa. Células imunoreativas para 5-HT foram detectadas em torno das células foliculares. Não foram observadas diferenças histológicas marcantes na tireoide de C. latirostris quando comparadas a outros mamíferos domésticos.

Histogenesis of Developing Human Thyroid.

In human beings the thyroid gland is one of the largest of the endocrine organs. It is one of the earliest endocrine organs to be differentiated and has an important hormonal role in embryonic development. The importance of thyroid gland is to promote growth and development of the brain during fetal life and for the first few years of post-natal life[1, 2]. The purposes of present study are 1)to study the microscopic structure of the human thyroid in different gestational age groups of normal stillborn foetuses; 2) to correlate the size of thyroid follicles; the nature and amount of colloid content of thyroid follicles at different stages of development. The study was carried out on 50 stillborn normal human foetuses. The microscopic structure of thyroid was studied under light microscope. The study concluded the developmental staging of thyroid as: the precolloid stage; the colloid formation stage; the folliculogenesis stage; secretory activity stage.

A study on maturation of thyroid gland in human fetuses

The thyroid gland is the first endocrine gland to appear on the embryonic period. Its organogenesis beginswhen the medium endoderm cells start getting thick, forming a diverticulum, in the primitive pharynx floor.In this report, we describe the histological maturation of thyroid gland in human fetuses, correlating the tissueaspects with pregnancy stage. Twenty human fetuses were used in this study in different developmental stages.The fetuses from 20 to 36 weeks (gestational age) were dissected and the thyroid gland removed. The glandwas then embedded in paraffin, cut in frontal plans portions and stained with Hematoxylin and Eosin (H&E).We observed that the maturation process of the thyroid follicles was directly correlated with the gestationalage, where human fetus with 23 weeks of age did not show any sign of follicles or colloid and the one with35 weeks of age presented follicles with colloid. The conclusion of this study was that maturation process ofthe thyroid follicles tissue is a linear process with the fetal development.

Estereología de la Glándula Tiroides Humana / Stereology of the Human Thyroid Gland

La glándula tiroides es una glándula endocrina voluminosa, impar, mediana y simétrica, que ocupa la parte anterior del cuello, en la unión del tercio inferior con los dos tercios superiores. La unidad funcional y estructural de la glándula tiroides es el folículo tiroideo. Los folículos están separados unos de otros por escaso tejido conectivo interfolicular. Se ha observado en modelos experimentales animales, diversos valores estereológicos de células foliculares, parafoliculares y coloide. El objetivo del trabajo fue determinar si existe un patrón estereológico en la glándula tiroides humana en un grupo etáreo y sexo definidos. Para ello, se ocupó una muestra de 6 glándulas tiroides humanas extraidas de cadáveres no fijados, de individuos adultos de sexo masculino, sin antecedentes de patología o alteración tiroídea.Se procesaron histológicamente con H-E para su estudio estereológico. Los resultados mostraron valores promedio para la densidad de volumen del tejido glandular (33,8 por ciento) y del coloide (63,17 por ciento), densidad de superficie del folículo tiroídeo (21,09 mm2/mm3), densidad de número de células foliculares (10,81 x 105 células/mm3) y parafoliculares (1,81 x 105 células/mm3). Conocido el volumen promedio de la glándula (21,3 mm3), se determinó el número total de células foliculares (230,22 x 105) y parafoliculares (38,33 x 105). Además, se determinó el número de folículos por mm2 (46,18 folículos/mm2). El conocimiento previo de los valores numéricos y proporciones normales estereólogicos permite establecer parámetros que determinen la alteración hiper o hipotrófica de origen endémico o exógeno que lleven a estratificar ciertas alteraciones, hecho observado en modelos experimentales donde las diferencias son significativas.

The thyroid gland is a an extensive, medium and symmetrical endocrine gland situated on the anterior side of the neck at the lower third and the upper third junction. The thyroid follicle is the functional and structural unit of the thyroid gland. Follicles are separated from each other by narrow interfollicular connective tissue. Stereological values of follicular, parafollicular and colloid containing follicles have been observed in experimental animal models. The aim of this study was to determine the existence of a stereological pattern in the human thyroid gland defined by age and sex. A sample of six human thyroid glands of adult males with no history of thyroid disease or disorder obtained from non fixed human cadavers; of these cadavers the gland was removed and processed for thyroid follicle density (21.09 mm 2/mm 3), follicular cell number density (10.81 x10 5 cells/mm3) and parafollicular (1.81 x 10 cells/mm 3). With the average gland volume (21.3 mm 3) we determined the total number of follicular cells (230.22 x 10 5) and parafollicular (38.33 x 105). The number of follicles per mm 2 (46.18 follicles/mm2) was also determined. Prior information and knowledge of numerical values and normal stereological proportions provides excellent parameters for determining hyper or hypotrophic endemic or exogenous alterations leading to stratification of certain disorders which was already observed in experimental models where differences amongst models were significant.

Anatomic relation between the external branch of the superior laryngeal nerve and the thyroid gland / Relação anatômica entre o ramo externo do nervo laríngeo superior e a glândula tireoide

AIM: This prospective study investigated the anatomic relations between the external branch of the superior laryngeal nerve (EBSLN), the superior thyroid artery (STA) and the thyroid gland in human cadavers. MATERIAL AND METHODS: Twenty-two human cadavers aged over 18 years old, less than 24 hours after death. RESULTS: The mean distance between the EBSLN and the superior pole of the thyroid gland was 7.68 ±3.07 mm. A tangent to the inferior edge of the thyroid cartilage between the EBSLN and the STA measured 4.24 ±2.67 mm. A line from the intersection of the EBSLN - related to the STA - to the superior pole of the thyroid gland measured 9.53 ±4.65 mm. A line from the EBSLN to the midline of the most caudal point of the thyroid cartilage measured 19.70 ±2.82 mm. A line from the RENLS to the midline on the most cranial point of the cricoid cartilage was 18.35 ±3.66 mm. CONCLUSION: There is a variable proximity relation between the EBSLN and the superior pole of the thyroid gland; this distance ranges from 3.25 to 15.75 mm. There was no evidence of significant variation between the measures in the ethnic groups comprising the sample.

OBJETIVO: Descrever, prospectivamente, a relação anatômica entre o ramo externo do nervo laríngeo superior (RENLS), a artéria tireoidea superior (ATS) e a glândula tireoide em cadáveres humanos. MATERIAL E MÉTODO: Foram dissecados 22 cadáveres humanos com idade superior a 18 anos, com menos de 24 horas de pós-morte. RESULTADOS: A medida entre o RENLS e o polo superior da glândula tireoide foi 7,68 +/- 3,07mm; entre o RENLS e a ATS foi de 4,24 +/- 2,67mm numa linha tangente ao bordo inferior da cartilagem tireoide; entre o cruzamento da ATS com o RENLS e o polo superior tireoidiano foi 9,53 +/- 4,65mm; entre o RENLS e a linha mediana do pescoço no ponto mais caudal da cartilagem tireoide foi 19,70 +/- 2,82mm; e entre o RENLS e a linha mediana do pescoço no ponto mais cranial da cartilagem cricoide foi 18,35 +/- 3,66mm. CONCLUSÕES: Há uma relação de proximidade variável entre o RENLS e o polo superior da glândula tireoide, variando de 3,25 a 15,75mm. Não constatou-se variações significativas entre as medidas para as diferentes etnias que compõem a amostra.

Evaluation of the importance of pyramidal lobe of thyroid gland anatomically in the surgical fields in Erbil

Dealing with the pyramidal lobe of the thyroid gland was not principally and cautiously under run in the surgery of the thyroid gland as the other two lateral lobes formerly, For this reason, the present work planned to study the anatomy and histopathology of the pyramidal lobe and to evaluate the degree their significance in surgical fields. The study included patients' preparation for operation, recording age, gender distributions, and measurement of pyramidal lobe moreover to view of directions. Blood supply and histopathology of the pyramidal lobe investigated during thyroid operations of 113 patients in Rizgary teaching hospital in Erbil. Goiter patient's sex distributions were as the following; 94 [83%] female and 19 [17%] male. PL frequency was 61/113 case [74%]; 50 [82%] females and 11 [18%] males. Pyramidal lobe directions were 21 directed right, in 40 cases to left. Arterial supplies of 34 cases were from a branch of the superior thyroid artery, in 27 cases were from isthmus. Venous drainage was joining venous plexus of the thyroid isthmus. Age distribution; females were commonly affected at [25 to 45y]. Males were [28-62y]. Pyramidal lobe mean length was [3.2 +/- 1.8 cm] and the width [1.6 +/- 0.7 cm]. Histopathologically, pyramidal lobe involved by principal thyroid lobes pathologies in 43 [71%] of the patients. This study alert us that the pyramidal lobe must be managed as a principal lobe during operations, because it may be a source of pitfall during the operation or it may be a future source of mucinous carcinoma of thyroid