A Rare Case of Ectopic Hidradenoma Papilliferum of the External Auditory Canal.

Hidradenoma papilliferum (HP) is a benign adnexal tumor, commonly affecting the anogenital region of middle-aged women. Clinically, HP typically presents as a slow-growing, unilateral, well-circumscribed, smooth skin-colored cystic dermal nodule, usually growing less than 1 cm in size. Reports of ectopic HP are exceedingly rare but have been identified in areas containing modified apocrine gland structures, most commonly on the head and neck, and have included ceruminous glands of the external ear canal, the Moll glands of the eyelid, mammary glands of the breast, maxillofacial region and areas on the scalp. To the best of our knowledge, there is only one case of ectopic HP located on the external ear canal reported in English literature. We present a second case of draining ectopic HP located on the conchal bowl of the external ear canal.

Ancillary immunohistochemical and molecular testing in the classification of cutaneous sweat gland/duct neoplasms: A validation study with emphasis on histomorphologic correlation and pathological diagnosis.

Sweat gland neoplasms represent a challenging area of dermatopathology, as they are relatively uncommon and often histopathologically complex. Recent studies have uncovered distinct immunohistochemical and molecular profiles in several sweat gland neoplasms, including digital papillary adenocarcinoma (DPA), papillary eccrine adenoma/tubular apocrine adenoma (PEA/TAA), poroid family tumors (PFT)/porocarcinoma, and clear cell hidradenoma (CCH)/clear cell hidradenocarcinoma (CCHCa). To further evaluate the diagnostic utility of ancillary studies in various sweat gland neoplasms, we performed an independent validation study in a cohort of patients with acral and non-acral tumors (9 DPA, 8 PEA/TAA, 13 PFT, 5 porocarcinoma, 23 CCH, 7 CCHCa, 6 sweat gland carcinoma not otherwise specified). p63 immunohistochemistry (IHC) demonstrated a myoepithelial pattern in 8/8 DPA and 4 of 4 tested PEA/TAA cases, and showed a ductal pattern in all tested PFT/porocarcinoma and CCH/CCHCa cases (42/42). All PEA/TAA (8/8) cases were positive for BRAF V600E IHC. 5 of 12 tested PFT and 5/5 porocarcinoma cases showed either positive staining with NUT IHC or harbored YAP1::NUTM1 fusion gene by RNA sequencing. MAML2 fluorescence in situ hybridization (FISH) was positive in all CCH and CCHCa cases (23/23 and 7/7, respectively). Our results further support the usefulness of appropriate ancillary studies in precise classification of sweat gland tumors, which may be routinely applied in diagnostic pathology practice when morphologic evaluation is in doubt.

Clear cell hidradenoma of the breast with MAML2 gene rearrangement.

Clear cell hidradenoma is a rare benign tumor of the breast, its origin and pathogenesis are controversial. We have experienced a case of breast clear cell hidradenoma with mastermind like transcriptional coactivator 2 (MAML2) gene rearrangement. The patient found a painless mass with a hard texture in the left breast areola without nipple discharge. Microscopically, the tumor was cystic and solid, locally arranged in a glandular structure, covered by single cuboidal cells; it was composed of clear cells, epidermoid cells, and basaloid cells; there were no necrosis or mitotic figures. Immunohistochemical staining showed that the tumor cells positively expressed low-molecular cytokeratin 7, low-molecular cytokeratins (Cam5.2), high-molecular cytokeratin 5/6, cytokeratin 14, CD117, and p63; and did not express calponin, and smooth muscle myosin heavy chain. The cuboidal cells were positive for SOX10 but negative for p63. Additionally, periodic acid-Schiff reaction showed purple-red granules in the tumor cytoplasm, but Alcian blue staining showed no blue mucus in the cytoplasm. The split signals of MAML2 gene were detected by fluorescence in situ hybridization. Subtle histological and immunophenotypical differences may help to distinguish breast clear cell hidradenoma from common breast tumors. Furthermore, the MAML2 gene rearrangement may be a molecular genetic characteristic of breast clear cell hidradenoma.

Remote Possibility of Post Aural Swelling as Nodular Hidradenoma: A Case Report.

A 30-year-old female patient presented with swelling over the left post aural region of 6 months duration which gradually increased in size. Cutaneous examination: A solitary, non-tender, mobile swelling of variable consistency over the post aural region. Dermoscopic examination: Revealed white and red areas. Diagnosis of nodular hidradenoma was made by histopathological examination.

Recurrent Malignant Sweat Gland Tumor.

Malignant sweat gland tumors are very rare. Hidradenocarcinoma is an uncommon malignancy arising from the intradermal ductal epithelium of eccrine sweat glands, usually in the sun-exposed parts of the body. It usually arises de novo but may develop from a benign hidradenoma. The diagnosis of hidradenocarcinoma is clinically challenging as it presents with varied consistency and clinically mimics other skin lesions such as chronic sebaceous cysts or epidermoid cysts. Hidradenocarcinoma is a highly aggressive tumor with a tendency for regional and distant spread. It is difficult to treat hidradenocarcinoma as it has high rates of morbidity and mortality and a very high incidence of recurrence. Here, we report a rare case of a 45-year-old woman who presented with a recurrent lump over the left arm diagnosed as primary hidradenocarcinoma.

Vulvar Hidradenoma Papilliferum.

Aim: This study examines the clinical and pathological characteristics, immune profile, histological occurrence, diagnosis, and differential diagnosis of vulvar hidradenoma papilliferum. Methods: An analysis was conducted on clinical data, histological patterns, and immunohistochemical findings from 45 cases of vulvar hidradenoma papilliferum, and relevant published articles were reviewed. Simultaneously, high-risk HPV typing was performed on these 45 cases. Results: The 45 cases of vulvar hidradenoma papilliferum displayed tumor sizes ranging from 0.3 to 2.0 cm and were observed to be pink or red in appearance. Vacuolated cytoplasm, large abnormal nuclei, distinct nucleoli, and scattered eosinophilic luminal secretions were observed in the glands. Positive staining for CK7 and progesterone receptor (PR) with focal mammaglobin and GCDFP-15 expression was found through immunohistochemistry. CK20 staining was noted as negative. Conclusion: Hidradenoma papilliferum is a rare benign tumor that originates in secretory glands. The diagnosis of this condition is aided by gross and immunohistochemical results, and differentiation from other conditions is necessary.

Giant Poroid Hidradenoma of the Forearm.

Poroid hidradenoma represents an uncommon and benign tumor originating from skin adnexa. It falls under the category of sweet duct neoplasms, along with poromas. It affects the elderly population most frequently. Typically, it emerges as a small, distinct, and painless lump beneath the skin's surface, often occurring on the head and neck regions. It is characterized by a low risk of malignant transformation. Accurate identification relies especially on histomorphological analysis considering the intricate resemblance it shares with other tumors originating from eccrine glands. Poroid hidradenoma has only recently been recognized, and only a limited number of cases have been reported in the medical literature. In this instance, we present an unusual occurrence of a giant poroid hidradenoma on the left forearm of an elderly patient.

Poroid Hidradenoma: Case Report and Comprehensive Review of the Literature.

Poroid hidradenoma (PH) is a rare benign adnexal tumor of eccrine differentiation. It is the rarest of the four described variants of poroid neoplasms. PHs characteristically share a hybrid of the architectural features of the hidradenoma, namely, tumor cells are entirely intradermal with both solid and cystic components, and the cytologic characteristics of the poroid neoplasms, containing predominantly poroid and cuticular cells. Many published reports of PH since its original discovery in 1990 state that "very few" cases of PH can be found in the literature. Here, we have identified a total of 75 published accounts of PH, including the case presented here, as well as the associated patient demographics, lesion characteristics, treatment, and outcomes. We suggest that while uncommon, PH is likely not exceptionally rare and could be an underreported diagnosis.

An Unusual Presentation of Nodular Hidradenoma.

Benign adnexal neoplasms are quite a common occurrence in adults, especially in the head and neck region. They raise suspicion for malignancy if there are red flag signs like rapid increase in size, pain, ulceration or recurrence. We hereby report a case of a middle-aged gentleman who consulted our surgical OPD with right-sided neck swelling, which was initially thought to be a dermoid cyst; on further evaluation, found to be a dermal sweat gland tumour with features of nodular hidradenoma. The point that is of interest but coincidence to note is that this swelling was preceded by a minor trauma. Characterising these swellings using simple imaging and pathological investigation modalities is important to study their behavioural pattern and add the same to our existing database. This will also help the treating surgeons to keep in mind the possibility of occurrence of such histologies in soft tissue swellings when they present with uncommon clinical features, instead of brushing them aside as the common epidermal or dermoid cysts. Incidence of malignancy is almost nil in nodular hidradenoma, which when found, is attributed to poor surgical clearance; hence the prudence to operate with adequate clearance is extremely significant in preventing the transformation of a mole into a mountain.

Metastatic hidradenocarcinoma: a report of two rare cases.

BACKGROUND: Hidradenocarcinoma is a rare malignant sweat gland tumour, characterized by a slow but aggressive course, with high rates of local recurrence and metastasis. Due to its rarity, histological criteria and therapeutic guidelines are poorly defined, posing a major challenge for clinicians and pathologists. OBJECTIVES: To present two new cases of metastatic hidradenocarcinoma as well as a review of the literature. MATERIALS & METHODS: We describe two case studies and a review of the literature based on a search using the MEDLINE (PubMed) electronic database. RESULTS: The first patient was a 61-year-old woman with a perimamillary hidradenocarcinoma that arose from the malignant transformation of a benign childhood lesion and developed regional lymph node metastases after wide excision and adjuvant radiotherapy. The second patient was a 63-year-old man who developed cutaneous and renal metastases several years after the complete excision of a lumbar hidradenocarcinoma. As far as we can ascertain, kidney metastasis from hidradenocarcinoma has not previously been described. CONCLUSION: Most authors recommend wide excision as the treatment of choice for hidradenocarcinoma, however, optimal adjuvant therapy remains to be determined. Our cases add to the limited knowledge available, but high-quality studies to find new effective treatments are needed.

Hidradenocarcinoma of the Female Breast: A Surgical Approach to a Rare Skin Tumor.

Clear-cell hidradenocarcinomas are extremely uncommon sweat gland tumors with a predilection for the head and neck. In the limited number of articles reporting breast involvement, the primary focus concerns this entity's histological and immunohistochemical characteristics. Since hidradenocarcinomas of the breast have the potential to resemble a primary breast carcinoma closely, diagnosis may be challenging. Therefore, the authors report the first case of hidradenocarcinoma of the breast, which features its macroscopic morphology. In addition, to increase physicians' awareness of this rare neoplasm, the article also aims to detail its surgical approach.

Genetic and Immunohistochemical Profiling of Mammary Hidradenoma and Comparison to Mucoepidermoid Carcinoma.

Mucoepidermoid carcinoma (MEC) is exceedingly rare in the breast, with <45 cases reported in the literature. Although estrogen receptor/progesterone receptor/human epidermal growth factor 2 triple-negative, MEC is characterized as a special subtype of breast carcinoma with significantly better prognosis than conventional basal-type tumors. Cutaneous hidradenoma (HA) is considered a benign adnexal neoplasm showing histomorphologic overlap with MEC. Rare cases of HA have also been reported in the breast, but these are relatively uncharacterized. In this study, we examined the clinicopathologic, immunohistochemical (IHC), and genetic features of 8 breast HAs, in comparison to 3 mammary MECs. All cases were positive for MAML2 break-apart fluorescence in situ hybridization. Eight cases demonstrated a CRTC1::MAML2 fusion, and one MEC harbored a CRTC3::MAML2 fusion; the latter is a novel finding in the breast. Mutational burden was very low, with only one HA exhibiting a MAP3K1 pathogenic alteration. By IHC, both MEC and HA demonstrated cell type-dependent expression of high- and low-molecular-weight keratins and p63, as well as negative to low-positive estrogen receptor and androgen receptor. Smooth muscle myosin and calponin highlighted an in situ component in the 3 cases of MEC; expression of these myoepithelial markers was negative in HAs. Additional distinguishing characteristics included the growth pattern and tumor architecture, the presence of glandular/luminal cells in HA, and overall higher IHC expression of SOX10, S100 protein, MUC4, and mammaglobin in MEC. Morphologic findings were also compared to a series of 27 cutaneous nonmammary HAs. Mucinous and glandular/luminal cells were identified in significantly more mammary HAs than nonmammary lesions. The findings provide insight into the pathogenesis of MAML2-rearranged neoplasms of the breast, underscore the overlapping genetic features of MEC and HA, and highlight similarities to their extramammary counterparts.

Clinicopathological Profile of Nodular Hidradenoma: A ten year Study in a Tertiary Care Center.

Nodular hidradenoma is a rare skin adnexal tumor of eccrine differentiation with predominant site being scalp and axillae. Due to its variable locations and unusual clinical presentation and no definite radiological criteria, histopathology seems to be the mainstay in diagnosing these tumors. Most of the lesions present as a cystic swelling and was clinically thought to be a sebaceous cyst/metastasis/carcinoma/sarcoma. In our study, we have included 37 cases and compared its varied clinical and radiological presentation.

Malignant Transformation of Retroauricular Hidradenoma in Hidradenocarcinoma in a Nine-Year-Old Patient: A Case Report.

Hidradenocarcinoma, a rare malignant entity that derives from sweat glands, is especially rare in the pediatric population. The treatment of choice is surgery. Radiation therapy is used only in selected patients. Chemotherapy is not used extensively because its effectiveness has not been demonstrated yet. This case report describes a nine-year-old female patient who presented in 2018 with a vegetative lesion in the right parietal region. After excisional surgery, pathology confirmed that the lesion was a benign hidradenoma. However, the lesion recurred six months later, and subsequent surgery revealed nodular hidradenoma with positive margins. In July 2019, a new heterogenous lesion appeared in the right retroauricular region, which was surgically removed. The pathology report found possible malignant characteristics, and the patient was referred to our hospital where she was diagnosed with poorly differentiated right retroauricular carcinoma with infiltrative and perineural permeation, along with homolateral lymph node metastasis. It was histologically compatible with a hidradenocarcinoma. The patient underwent a wide-margin excision and homolateral total cervical lymphadenectomy, followed by adjuvant radiotherapy. The last follow-up MRI was negative for disease recurrence or metastasis; however, a slow-growing node on the left jugular chain (level II) was noted. The patient is on regular follow-ups to monitor disease status and treatment-related adverse events. This case highlights the challenges of diagnosing and treating hidradenocarcinoma, a rare malignancy that requires aggressive management with a multidisciplinary approach. More robust clinical evidence is needed to define the best treatment approach for these aggressive tumors.

Clinicopathological Spectrum of Benign Skin Adnexal Tumors in the Pakistani Population: A Single-Center Study.

Background Skin adnexal tumors (SATs) are categorized per the site of origin, for example, hair follicles, sebaceous glands, and sweat glands. In our population, there is limited information related to the clinicopathological characteristics of these tumors. Management and prognosis depend largely upon the morphological type of the tumor. In this study, we assessed the disease spectrum and most prevalent subtypes of benign SATs. Methodology An analysis of 565 cases was conducted in this cross-sectional study between January 2018 and December 2022, using a non-probability consecutive sampling approach. Patient age, gender, site of involvement, and diagnosis were documented according to the fourth edition of the WHO Classification of Skin Tumors published in 2018. Data were entered and analyzed using SPSS Version 26.0 (IBM Corp., Armonk, NY). Results Our study had 565 patients, out of which 271 (47.9%) were males and 294 (52.1%) were females. The mean age was 40.97±19.3 years (range, 2-100 years). Anatomical site variations were as follows, head and neck (n=336, 59.4%), extremities (n=124, 22%), trunk (n=84, 14.9%), and genital areas (n=21, 3.7%). The most common histological subtypes of benign SATs were sweat gland origin (n=350, 62.0%), followed by hair follicle origin (n=161, 28.5 %), and sebaceous gland origin (n=54, 9.5%). Conclusion Sweat gland tumors were the most prevalent class of benign SATs in our study, in which hidradenoma and poroma were the most frequent subtypes. Hair follicle origin was the second most prevalent class of tumors with pilomatricoma being the most frequent. Sebaceous tumors were overall uncommon; nevus sebaceous of Jadasshon was the most common tumor in this class.

Poroma. Estudio retrospectivo de 80 pacientes en un hospital terciario / Poroma: A Retrospective Series of 80 Patients at a Tertiary Care Hospital

Introducción El poroma es un tumor anexial benigno exclusivo de la piel que tiene una predilección por la piel palmoplantar.Objetivo Analizar las características clínicas del poroma en nuestra población.Material y métodosEstudio retrospectivo de los pacientes con poroma diagnosticados entre 2002 y 2021. Se revisaron las historias clínicas para obtener los siguientes datos: edad, sexo, localización, número de lesiones, diámetro, tiempo de evolución, características clínicas de los tumores, diagnóstico clínico de sospecha, estado de los márgenes de resección, desarrollo de recidiva y tiempo de seguimiento. Las variables categóricas se compararon mediante la prueba exacta de Fisher. Las variables continuas se compararon mediante la prueba t de Student cuando se confirmó la normalidad de la distribución de datos. De lo contrario, se realizó la prueba U de Mann-Whitney. ResultadosSe incluyeron 80 pacientes con poroma (31 mujeres y 49 varones, con una edad mediana de 65,5 años y rango intercuartílico [RIC] 29 años). La mediana del tiempo medio de evolución fue de 12 meses, RIC 21 meses y la mediana del diámetro 8mm, RIC 7. Ningún paciente presentó lesiones múltiples. Las lesiones se localizaron en la cabeza y el cuello en 13 casos, en el tronco en 13, en las extremidades superiores en 11 y en las extremidades inferiores en 43. Veintitrés lesiones (28,8%) se localizaron en piel acral (palmas 5, plantas 18). La localización en el cuero cabelludo fue más frecuente en el sexo femenino (p=0,041). Las lesiones acrales fueron con mayor frecuencia eritematosas (p=0,014). Cinco pacientes presentaron recidiva local. Conclusiones Aunque los poromas son especialmente frecuentes en la piel acral, sobre todo de los pies, en la mayoría de pacientes se localizan en otras regiones anatómicas (71,3%). El aspecto clínico clásico de lesión exofítica eritematosa se observa con una mayor frecuencia en las lesiones acrales. (AU)

Background Poroma is a benign, exclusively cutaneous, adnexal tumor with a predilection for palmoplantar skin. Objective To analyze the clinical characteristics of poroma in our population.Material and methodsRetrospective study of patients diagnosed with poroma between 2002 and 2021. We conducted a chart review to record age; sex; number, location, and diameter of lesions; time since onset; clinical characteristics; suspected clinical diagnosis; resection margin status; recurrences; and follow-up duration. Categorical variables were compared using the Fisher exact test. Continuous variables were compared using the t test or the Mann-Whitney U test depending on whether they were normally or nonnormally distributed. Results We studied 80 patients (31 women and 49 men) with a median (interquartile range [IQR]) age of 65.5 (29) years. Median time since onset of poroma was 12 (21) months. Median lesion diameter was 8(7)mm, and none of the patients had multiple lesions. The lesions were located on the head and neck in 13 cases, the trunk in 13, the upper extremities in 11, and the lower extremities in 43. Twenty-three lesions (28.8%) were located at acral sites (5 on the palms and 18 on the soles). Women were more likely to have scalp lesions (P=.041). Acral lesions were more likely to be erythematous (P=.014). Five patients experienced local recurrence. Conclusions Although poromas are particularly common in acral locations (especially the feet), most of the lesions in our series (71.3%) were located elsewhere. Acral lesions were more likely to show the classic clinical features of erythema and exophytic growth. (AU)

[Translated article] Poroma: A Retrospective Series of 80 Patients at a Tertiary Care Hospital / Poroma. Estudio retrospectivo de 80 pacientes en un hospital terciario

Background Poroma is a benign, exclusively cutaneous, adnexal tumor with a predilection for palmoplantar skin. Objective To analyze the clinical characteristics of poroma in our population.Material and methods Retrospective study of patients diagnosed with poroma between 2002 and 2021. We conducted a chart review to record age; sex; number, location, and diameter of lesions; time since onset; clinical characteristics; suspected clinical diagnosis; resection margin status; recurrences; and follow-up duration. Categorical variables were compared using the Fisher exact test. Continuous variables were compared using the t test or the Mann–Whitney U test depending on whether they were normally or nonnormally distributed. Results We studied 80 patients (31 women and 49 men) with a median (interquartile range [IQR]) age of 65.5 (29) years. Median time since onset of poroma was 12 (21) months. Median lesion diameter was 8 (7)mm, and none of the patients had multiple lesions. The lesions were located on the head and neck in 13 cases, the trunk in 13, the upper extremities in 11, and the lower extremities in 43. Twenty-three lesions (28.8%) were located at acral sites (5 on the palms and 18 on the soles). Women were more likely to have scalp lesions (P=.041). Acral lesions were more likely to be erythematous (P=.014). Five patients experienced local recurrence. Conclusions Although poromas are particularly common in acral locations (especially the feet), most of the lesions in our series (71.3%) were located elsewhere. Acral lesions were more likely to show the classic clinical features of erythema and exophytic growth. (AU)

Introducción El poroma es un tumor anexial benigno exclusivo de la piel que tiene predilección por la piel palmoplantar. Objetivo Analizar las características clínicas del poroma en nuestra población. Material y métodos Estudio retrospectivo de los pacientes con poroma diagnosticados entre 2002 y 2021. Se revisaron las historias clínicas para obtener los siguientes datos: edad, sexo, localización, número de lesiones, diámetro, tiempo de evolución, características clínicas de los tumores, diagnóstico clínico de sospecha, estado de los márgenes de resección, desarrollo de recidiva y tiempo de seguimiento. Las variables categóricas se compararon mediante la prueba exacta de Fisher. Las variables continuas se compararon mediante la prueba t de Student cuando se confirmó la normalidad de la distribución de datos. De lo contrario, se realizó la prueba U de Mann-Whitney. Resultados Se incluyeron 80 pacientes con poroma (31 mujeres y 49 varones, con una edad mediana de 65,5años y rango intercuartílico [RIC] de 29 años). La mediana del tiempo medio de evolución fue de 12meses, RIC 21 meses, y la mediana del diámetro 8mm, RIC 7. Ningún paciente presentó lesiones múltiples. Las lesiones se localizaron en la cabeza y en el cuello en 13 casos, en el tronco en 13, en las extremidades superiores en 11 y en las extremidades inferiores en 43. Veintitrés lesiones (28,8%) se localizaron en piel acral (palmas 5, plantas 18). La localización en el cuero cabelludo fue más frecuente en el sexo femenino (p=0,041). Las lesiones acrales fueron con mayor frecuencia eritematosas (p=0,014). Cinco pacientes presentaron recidiva local. Conclusiones Aunque los poromas son especialmente frecuentes en la piel acral, sobre todo de los pies, en la mayoría de pacientes se localizan en otras regiones anatómicas (71,3%). El aspecto clínico clásico de lesión exofítica eritematosa se observa con una mayor frecuencia en las lesiones acrales. (AU)

Poroma: A Retrospective Series of 80 Patients at a Tertiary Care Hospital. / Poroma. Estudio retrospectivo de 80 pacientes en un hospital terciario.

BACKGROUND: Poroma is a benign, exclusively cutaneous, adnexal tumor with a predilection for palmoplantar skin. OBJECTIVE: To analyze the clinical characteristics of poroma in our population. MATERIAL AND METHODS: Retrospective study of patients diagnosed with poroma between 2002 and 2021. We conducted a chart review to record age; sex; number, location, and diameter of lesions; time since onset; clinical characteristics; suspected clinical diagnosis; resection margin status; recurrences; and follow-up duration. Categorical variables were compared using the Fisher exact test. Continuous variables were compared using the t test or the Mann-Whitney U test depending on whether they were normally or nonnormally distributed. RESULTS: We studied 80 patients (31 women and 49 men) with a median (interquartile range [IQR]) age of 65.5 (29) years. Median time since onset of poroma was 12 (21) months. Median lesion diameter was 8(7)mm, and none of the patients had multiple lesions. The lesions were located on the head and neck in 13 cases, the trunk in 13, the upper extremities in 11, and the lower extremities in 43. Twenty-three lesions (28.8%) were located at acral sites (5 on the palms and 18 on the soles). Women were more likely to have scalp lesions (P=.041). Acral lesions were more likely to be erythematous (P=.014). Five patients experienced local recurrence. CONCLUSIONS: Although poromas are particularly common in acral locations (especially the feet), most of the lesions in our series (71.3%) were located elsewhere. Acral lesions were more likely to show the classic clinical features of erythema and exophytic growth.