Cutaneous mast cell tumor in a captive Bush dog (Speothos venaticus): pathological and immunophenotypical aspects - case report / Mastocitoma cutâneo em um cachorro-do-mato vinagre (Speothos venaticus) de cativeiro: aspectos patológicos e imunofenotípicos - relato de caso

A senile male captive bush dog (Speothos venaticus) presented a small perianal cutaneous nodule. Histologically, there was an ulcerated round cell tumor composed of well differentiated mast cells with abundant intracytoplasmic purple Giemsa-positive granules, with a diffuse eosinophilic infiltrate. Immunohistochemistry revealed that 30% of the neoplastic cells were positive for Kit in the cytoplasm and cell membrane, and all neoplastic cells were negative for MAC and CD3. Less than 10% of the neoplastic cells were positive for Ki67. At necropsy other primary tumors were identified in this animal, including an intestinal adenoma, an adrenal cortex adenoma and a testicular interstitial cell tumor.(AU)

Um cachorro-vinagre (Speothos venaticus) apresentou um nódulo cutâneo pequeno na região perianal. Histologicamente havia neoplasia cutânea de células redondas e ulcerada, constituída por mastócitos bem diferenciados, com abundantes grânulos citoplasmáticos metacromáticos na coloração de Giemsa e infiltrado eosinofílico difuso. A imuno-histoquímica demonstrou que 30% das células neoplásicas eram positivas para a proteína Kit no citoplasma e na membrana celular. As células foram negativas para MAC e CD3. Menos de 10% das células neoplásicas foram positivas para Ki67. Durante a necropsia, foram identificados outros tumores primários, como adenoma intestinal, adenoma cortical da adrenal e tumor de células intersticiais do testículo.(AU)

Case report of a clinically indolent but morphologically high-grade cutaneous mast cell tumor in an adult: Atypical cutaneous mastocytoma or mast cell sarcoma?

We present a case of an adult male with a solitary mast cell tumor of the skin with unusual nuclear pleomorphism and mitotic activity. The tumor was excised, recurred within 2 years, was reexcised after 4 years and did not recur >6 years after diagnosis. The tumor showed progressive cytonuclear atypia and a high mitotic and proliferation rate by Ki67-staining from the onset. No KIT mutations were identified in the tumor and bone marrow. Serum tryptase levels and a bone marrow aspirate and trephine biopsy were normal. Although the histomorphology of the skin tumor was consistent with mast cell sarcoma, the clinical behavior without systemic progression argued against this diagnosis. The tumor was finally considered as atypical mastocytoma, borderline to mast cell sarcoma. Currently, the patient is in close follow-up and still in complete remission.

Prognostic value of immunohistochemical markers in canine cutaneous mast cell tumours: A systematic review and meta-analysis.

Histological grading systems remain cornerstones in the prognosis of canine cutaneous mast cell tumours (MCTs), but the distinct biological behaviour of each tumour often necessitates the use of complementary markers. Although a plethora of immunohistochemical markers have been proposed as prognostic factors, few are presently applied in routine diagnosis. This systematic review and meta-analysis was designed to establish which immunohistochemical markers have verifiable prognostic value for cutaneous MCTs in dogs. A Boolean search of five databases identified 200 articles for screening, of which 73 were selected for full-text assessment and 24 ultimately included in the systematic review. Odds Ratio (OR) was adopted as the summary measure for subsequent meta-analysis but only 15 articles, relating to the immunomarkers Ki-67 (9), KIT (5), and BAX (2), provided either a value for OR or sufficient data to calculate this statistic. Meta-analysis verified that canine cutaneous MCTs with elevated expression of Ki-67 or BAX, as well aberrant immuno-expression of KIT, showed an increased odds of death, with respective OR values of 11.2 (95% CI 6.3-20.0; p < .01), 9.9 (95% CI 1.3-73.6; p = .03), and 4.1 (95% CI 1.1-15.3; p = .03). Despite KIT, Ki67, and BAX arise as suitable prognostic factor for canine MCTs, this study highlighted the lack of important clinical and statistical data in many published articles, rendering it impossible to complete the meta-analysis of several potentially valuable immunohistochemical markers.

[Isolated mastocytoma in children: a case study]. / Mastocytome solitaire de l'enfant: à propos d'un cas.

Isolated mastocytoma is the most common form of mastocytosis in children. Prognosis is good, as in all other forms of mastocytosis in children, with possibility of spontaneous regression. Dermocorticoids can accelerate this regression, as it is the case for our patient.

Use of different fixation times and application of two immunohistochemical methods for detection of KIT and Ki67 proteins in canine cutaneous mast cell tumors / Utilização de diferentes tempos de fixação e métodos imuno-histoquímicos na detecção das proteínas KIT e Ki67 em mastocitomas cutâneos caninos

Due to the high prevalence of mast cell tumors (MCTs) in the diagnostic routine, several factors, especially prognostic, have been sought to determine the biological behavior of these neoplasms. Immunohistochemistry (IHC) is one of the main tools utilized to biologically differentiate more aggressive tumors from less aggressive ones. However, some immunostainings are influenced by formalin fixation, interfering with the results. This is both a retrospective and prospective study of MCTs diagnosed in laboratory routine. A total of 25 samples, without knowledge about fixation time, were analyzed in the retrospective study, whereas 12 samples, with known fixation times, were assessed in the prospective study. Two histologic grading systems (Patnaik and Kiupel), special staining of toluidine blue, and IHC for KIT and Ki67 proteins were applied in both studies. Additionally, two amplification systems (biotinylated and non-biotinylated) for Ki67 protein and counting of the argyrophilic nucleolar organizing regions (AgNOR method) were tested in the prospective study. In the retrospective study, greater agreement between the evaluating pathologists was observed when the Kiupel system was used. IHC staining for KIT protein was effective in both studies, regardless of fixation time. IHC staining for Ki67 protein was highly sensitive to formaldehyde, and staining failure was observed in 56% of the cases in the retrospective study. In the prospective study, samples fixed for longer than 24 hours showed a reduction in the number of stained cells (altering the determination of the cell growth fraction) or showed absence of IHC staining in both amplification systems. The use of the AgNOR method to evaluate the rate of cell proliferation may be an alternative when the fixation time of the neoplasm is unknown or longer than 24 hours.(AU)

Devido a alta prevalência dos mastocitomas cutâneos caninos (MCCs) na rotina diagnóstica, vários fatores, especialmente fatores prognósticos, têm sido buscados para auxiliar na determinação do comportamento biológico desse neoplasma. A imuno-histoquímica é uma das principais ferramentas empregadas para diferenciar tumores biologicamente mais agressivos de tumores menos agressivos. Entretanto, algumas imunomarcações sofrem influência pela fixação em formol, interferindo nos resultados. Este estudo compreendeu avaliar através de uma etapa retrospectiva e uma etapa prospectiva casos de MCCs diagnosticados na rotina laboratorial. Um total de 25 amostras, sem conhecimento do tempo de fixação, foi analisado no estudo retrospectivo e 12 amostras, com tempos de fixação conhecidos, no estudo prospectivo. Foram aplicados nos dois estudos, dois sistemas de graduação histológica (Patnaik e Kiupel), a coloração especial de azul de toluidina e a imuno-histoquímica para as proteínas KIT e Ki67. Adicionalmente, no estudo prospectivo, foram testados dois sistemas de amplificação (biotinilado e não biotinilado) para a proteína Ki67 e a técnica de AgNOR (contagem das regiões organizadoras nucleolares argirofílicas). Na etapa retrospectiva, observou-se uma maior concordância entre os patologistas avaliadores quando o sistema Kiupel foi utilizado. A imunomarcação para KIT se manteve eficaz em ambos os estudos, independentemente do tempo de fixação. A imunomarcação para o Ki67 mostrou-se altamente sensível ao tempo de fixação em formol, sendo observada falha na imunomarcação em 56% dos casos do estudo retrospectivo. No estudo prospectivo, constatou-se que amostras fixadas por mais de 24 horas em formol apresentaram redução na quantidade de células imunomarcadas (alterando a determinação da fração de crescimento celular) ou apresentaram ausência de imunomarcação em ambos os sistemas de amplificação. A utilização do método AgNOR, para avaliar a taxa de proliferação celular, pode ser uma alternativa quando o tempo de fixação do neoplasma for desconhecido ou superior a 24 horas.(AU)

Childhood Solitary Cutaneous Mastocytoma: Clinical Manifestations, Diagnosis, Evaluation, and Management.

BACKGROUND: The diagnosis of solitary cutaneous mastocytoma is mainly clinical, based on lesion morphology, the presence of a positive Darier sign, and the absence of systemic involvement. Knowledge of this condition is important so that an accurate diagnosis can be made. OBJECTIVE: To familiarize physicians with the clinical manifestations, diagnosis, evaluation, and management of a solitary cutaneous mastocytoma. METHODS: A PubMed search was completed in Clinical Queries using the key term "solitary cutaneous mastocytoma". The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. Only papers published in English language were included. The information retrieved from the above search was used in the compilation of the present article. RESULTS: Typically, a solitary cutaneous mastocytoma presents as an indurated, erythematous, yellow- brown or reddish-brown macule, papule, plaque or nodule, usually measuring up to 5 cm in diameter. The lesion often has a peau d'orange appearance and a leathery or rubbery consistency. A solitary cutaneous mastocytoma may urticate spontaneously or when stroked or rubbed (Darier sign). Organomegaly and lymphadenopathy are characteristically absent. The majority of patients with skin lesions that erupt within the first two years of life have spontaneous resolution of the lesions before puberty. Treatment is mainly symptomatic. Reassurance and avoidance of triggering factors suffice in most cases. CONCLUSION: The diagnosis is mainly clinical, based on the morphology of the lesion, the presence of a positive Darier sign, and the absence of systemic involvement. A skin biopsy is usually not necessary unless the diagnosis is in doubt.

Utility of flow cytometry in canine primary cutaneous and matched nodal mast cell tumor.

Mast cell tumors (MCT) are among the most frequent tumors in dogs, but studies regarding canine mast cell immunophenotype are lacking. The aim of this study was to assess the feasibility of flow cytometric analysis of MCTs, to describe canine MCTs immunophenotype(s), and to evaluate the ability of flow cytometry to detect mast cells in lymph node aspirates. Thirty-four primary canine MCTs and 12 draining lymph nodes were evaluated regarding the expression of CD117, IgE, CD11b, CD18, CD44, CD34, CD25 and CD45. Distinct populations attributable to mast cells and eosinophils were recognized based on light scatters and CD117 positivity. Common antigens (CD18, CD45, CD44) and CD117 were detected in all cases; positivity for IgE and CD11b was found in 28 (82%) and 23 (68%) cases respectively, while CD34 and CD25 were occasionally expressed. A single multicolor tube (IgE/CD117/CD11b/CD21/CD5) allowed the identification of mast cells in lymph nodes, showing a high correlation with cytology in quantifying mast cells infiltration. In conclusion, flow cytometric analysis can be applied to characterize canine MCTs and can be used to detect the presence of mast cells in lymph nodes. The immunophenotype abnormalities observed may be useful to confirm the neoplastic nature of such mast cells but the diagnostic usefulness of atypical antigen expression remains to be clarified.

Paediatric mastocytosis: long-term follow-up of 53 patients with whole sequencing of KIT. A prospective study.

BACKGROUND: Mastocytosis is a heterogeneous group of clinical disorders characterized by the abnormal accumulation of mast cells. The adult and paediatric forms differ in their clinical and genetic features and outcomes. OBJECTIVES: To describe the clinical evolution of a well-characterized cohort of paediatric mastocytosis (PM), and to analyse the relationship between KIT mutation and the clinical course. METHODS: This was a prospective cohort study performed at the National Clinical Reference Center for Mastocytosis. Diagnosis was confirmed by identification of KIT mutation on lesional skin biopsy. Mastocytosis subtype, mast cell mediator-related symptoms (MC MRS) and clinical course were recorded. Fifty-three patients with PM and > 4 years of disease course were enrolled. The mean ± SD age at the final evaluation was 13·2 ± 4·8 years. The main outcome was the type of KIT mutation as a predictor of evolution and clinical characteristics. RESULTS: Patients presented with maculopapular cutaneous mastocytosis (n = 44), diffuse cutaneous mastocytosis (n = 6) or mastocytoma (n = 3). The mean duration of disease was 12·1 years. Substantial or partial cutaneous regression (18 of 53 and 16 of 53), stabilization or aggravation (16 of 53) and complete cutaneous regression (three of 53) were noted. MC MRS mainly regressed (21 of 53). For 22 patients, evolution of MC MRS and evolution of cutaneous lesions were different. No significant association between evolution and KIT mutation or between evolution and type of cutaneous mastocytosis was found. A late onset of the disease (after 2 years) is associated with worse evolution. CONCLUSIONS: PM is not systematically self-regressive. MC MRS manifestations and cutaneous lesions can persist or increase overtime. KIT mutation is not a predictor of evolution.

Increased expression of tissue inhibitor of metalloproteinase-1 correlates with improved outcome in canine cutaneous mast cell tumours.

Canine mast cell tumour (MCT) is a biologically heterogeneous disease. The extracellular matrix degradation promoted by matrix metalloproteinases (MMPs) has been studied in an attempt to elucidate the mechanisms involved in the biological behaviour of tumours. The aim of this study was to characterize the expression of MMP-2 and -9 and tissue inhibitors of metalloproteinase (TIMP)-1 and -2 in canine cutaneous MCTs and to evaluate their prognostic values. Immunohistochemical staining for MMP-2, MMP-9, TIMP-2 and TIMP-1 was performed in 46 canine cases of MCTs. TIMP-1 expression showed an independent prognostic value for post-surgical survival and disease-related mortality. Dogs with MCTs showing less than 22.9% mast cell TIMP-1 positivity were more prone to die because of the disease and had a shorter post-surgical survival. This article suggests the involvement of TIMP-1 in MCT progression, by contributing to a good outcome in patients with MCTs.

Use of a 2-tier histologic grading system for canine cutaneous mast cell tumors on cytology specimens.

BACKGROUND: Mast cell tumors (MCT) represent the most common malignant skin tumor in the dog. Diagnosis of an MCT can be achieved through cytologic examination of a fine-needle aspirate. However, the grade of the tumor is an important prognostic marker and currently requires histologic assessment. Recently a 2-tier histologic grading system based on nuclear features including number of mitoses, multinucleated cells, bizarre nuclei, and karyomegaly was proposed. OBJECTIVES: The aim of this study was to assess if the cytomorphologic criteria proposed in the 2-tier histologic grading system are applicable to cytology specimens. METHODS: A total of 141 MCT specimens reported as grade I, II, or III according to the Patnaik system with both histologic specimens and fine-needle aspirates available were histologically and cytologically reevaluated in a retrospective study. RESULTS: According to the 2-tier grading system, 38 cases were diagnosed histologically as high-grade and 103 as low-grade MCT. Cytologic grading resulted in 36 high-grade and 105 low-grade tumors. Agreement between histologic and cytologic grading based on the 2-tier grading system was achieved in 133 cases (sensitivity 86.8%, specificity 97.1%, kappa value 0.853), but 5 high-grade tumors on histology were classified as low-grade on cytology. CONCLUSION: Cytologic grading of MCT in the dog is helpful for initial assessment. However, the reliability of cytology using the 2-tier grading system is considered inadequate at this point. Prospective studies including clinical outcome should be pursued to further determine diagnostic accuracy of cytologic mast cell grading.

Pseudoangiomatous xanthelasmoid mastocytosis: two case reports showing the hypervascularity of this rare variant of cutaneous mastocytosis.

Xanthelasmoid mastocytosis or xanthelasmoidea is a rare clinical variant of cutaneous mastocytosis characterized by a yellow hue of the clinical lesions, which are often misdiagnosed as juvenile xanthogranuloma. We present two pediatric cases of xanthelasmoid mastocytosis presenting as isolated mastocytomas, which are notable histopathologically for their hypervascularity. This pseudoangiomatous variant of cutaneous mastocytosis is important for pathologists to have knowledge of, so that a diagnosis of a vascular tumor is not rendered accidentally. The yellow hue has previously been explained by the usual deep and solid dermal mast cell infiltrate. In the two presented cases, however, the mast cell infiltrate was sparse, and the yellow color cannot be related to infiltrate density. We believe that the hypervascularity is at least one factor in the production of clinical xanthelasmoid appearance, and we propose the term 'pseudoangiomatous xanthelasmoid mastocytosis' to properly describe this rare variant of cutaneous mastocytosis.

Topical corticosteroids versus "wait and see" in the management of solitary mastocytoma in pediatric patients: a long-term follow-up.

Management of patients affected by mastocytoma (MS) includes avoiding triggering factors of mast cell degranulation, and administration of symptomatic treatment. We evaluated topical steroid treatment efficiency on the clinical course of MS in a group of patients, comparing the results with another untreated group.We retrospectively evaluated clinical data of 176 patients under 15 years of age, affected by MS and referred to our Dermatological Pediatric Service from 1996 to 2010. Ninety-one of 176 children were treated with topical steroids. Follow-up was possible in 130 of 176 patients and lasted for 56.3 months on average. We compared 62 treated and 68 untreated patients. There was not statistic difference between the two groups: (i) in the number of healed or partially improved cases; and (ii) in the time of partial regression, although it is quicker with therapy. The time of healing is 16.4 months (on average) with treatment, and 34.7 months (on average, p = 0.001) without any treatment. The resolution of MS is independent of therapy administration, but the time of healing is statistically faster using the local steroids. An appropriate treatment with them is effective and safe, considering the long time needed for spontaneous resolution.

Grau de malignidade do mastocitoma cutâneo canino quanto a localização segundo as classificações de Patnaik et al. (1984) e Kiupel et al. (2011) / Degree of malignancy of the canine cutaneous mast cell tumor as forlocation according to the classifications of Patnaik et al. (1984) and Kiupel et al. (2011)

Objetivou-se com o presente trabalho coletar dados epidemiológicos relacionados com o mastocitoma canino, além de verificar se há relação entre sua malignidade e localização e, por fim, comparar os métodos de classificação histopatológica segundo Patnaik et al. (1984) e segundo Kiupel et al. (2011). Informações foram coletadas da ficha clínica de 55 cães e 60 fragmentos de pele com mastocitomas foram avaliados histologicamente. Verificou-se que a ocorrência de mastocitoma cutâneo não é influenciada pelo sexo e raça, porém cães sem raça definida e boxers são mais acometidos. Não há uma faixa etária susceptível bem definida, sendo o mastocitoma mais frequente em cães de 8 a 9 anos de idade. A região mais acometida foi a inguinal (50%) e a cabeça a região que apresentou mastocitomas com maior malignidade. Utilizando a classificação de Patnaik et al. (1984) houve diferença significativa entre as classificações histopatológicas de mastocitoma avaliadas por diferentes patologistas, o que não ocorreu utilizando a classificação de Kiupel et al. (2011). Pode-se dizer então que a classificação de Kiupel et al. (2011) gera menor divergência nos diagnósticos, demonstrando-se um método simples e eficaz para a avaliação histopatológica de mastocitoma.

The aim of the present study is to collect epidemiological data related to the canine mastocytoma, to check if there is relationbetween malignancy and its location and, finally, to compare the methods of histopathological classification according to Patnaiket al. (1984) and Kiupel et al. (2011). Informations were collected from the clinical record of 55 dogs and 60 fragments of skinwith a diagnosis of mast cell tumor were evaluated histologically. It was found that the occurrence of cutaneous mast cell tumorsis not influenced by gender and race, but dogs without defined breed and boxers are most affected. There is not a well-definedsusceptible age, but the most mast cell tumors in dogs often 8 to 9 years old. The highest affected region was inguinal (50%) andhead proved a region with higher malignancy. Using the classification Patnaik et al. (1984) there was a significant difference betweenthe histopathological ratings mastocytoma evaluated by different pathologists, which did not occur using the classification Kiupel etal. (2011). It can be said then that the classification Kiupel et al. (2011) generates less divergence in the diagnosis, demonstratinga simple and effective method for histopathological evaluation of mastocytoma.

Adult-onset mastocytosis in the skin is highly suggestive of systemic mastocytosis.

Adult-onset urticaria pigmentosa/mastocytosis in the skin almost always persists throughout life. The prevalence of systemic mastocytosis in such patients is not precisely known. Bone marrow biopsies from 59 patients with mastocytosis in the skin and all available skin biopsies (n=27) were subjected to a meticulous cytological, histological, immunohistochemical, and molecular analysis for the presence of WHO-defined diagnostic criteria for systemic mastocytosis: compact mast cell infiltrates (major criterion); atypical mast cell morphology, KIT D816V, abnormal expression of CD25 by mast cells, and serum tryptase levels >20 ng/ml (minor criteria). Systemic mastocytosis is diagnosed when the major diagnostic criterion plus one minor criterion or at least three minor criteria are fulfilled. Systemic mastocytosis was confirmed in 57 patients (97%) by the diagnosis of compact mast cell infiltrates plus at least one minor diagnostic criterion (n=42, 71%) or at least three minor diagnostic criteria (n=15, 25%). In two patients, only two minor diagnostic criteria were detectable, insufficient for the diagnosis of systemic mastocytosis. By the use of highly sensitive molecular methods, including the analysis of microdissected mast cells, KIT D816V was found in all 58 bone marrow biopsies investigated for it but only in 74% (20/27) of the skin biopsies. It is important to state that even in cases with insufficient diagnostic criteria for systemic mastocytosis, KIT D816V-positive mast cells were detected in the bone marrow. This study demonstrates, for the first time, that almost all patients with adult-onset mastocytosis in the skin, in fact, have systemic mastocytosis with cutaneous involvement.