Cutaneous mast cell tumor in a captive Bush dog (Speothos venaticus): pathological and immunophenotypical aspects - case report

D.O Santos,T.P Carvalho,C.M Coelho,R.L Santos,A.R Oliveira,E.S Veloso,H.P Tinoco,F Pierezan,G.C Martins,A.T.P.G Ribeiro,N.F Paula,E Ferreira

doi:10.1590/1678-4162-12251

Abstract

ABSTRACT 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.

Highlights

Mast cell tumors are among the most common cutaneous tumors in domestic dogs
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
At necropsy other primary tumors were identified in this animal, including an intestinal adenoma, an adrenal cortex adenoma and a testicular interstitial cell tumor

Summary

Introduction

Mast cell tumors are among the most common cutaneous tumors in domestic dogs It is uncommon in cats and rare in other domestic animal species (Kiupel, 2017). Mutations in the c-kit gene is an important prognostic factor in domestic dogs, and the aberrant subcellular localization of the KIT protein, as demonstrated by immunohistochemistry, is usually correlated with mutations in the gene, being an indicative of a high-grade tumor (Thamm et al, 2019). Mast cell tumors are usually cutaneous or subcutaneous, extracutaneous manifestations may occur, such as the rare intestinal presentation (Kiupel, 2017). This report aims to characterize by histopathology and immunohistochemistry a cutaneous mast cell tumor in a captive bush dog

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