Nine-Month-Old canine cutaneous mastocytoma with immunohistochemical profile and c-Kit mutation evaluation

Abstract

Mastocytoma is among the most common skin tumors in dogs, having great importance in the clinical and surgical routine, but its occurrence in animals under one year of age is considered rare. Its diagnosis is made through anatomopathological exams, especially histopathology, which allows for grading and prognostic evaluation. Treatment may involve multiple therapeutic approaches, such as chemotherapy, electrochemotherapy, tyrosine kinase receptor inhibitors, radiotherapy and cryosurgery, however the most indicated modality is surgical excision, which provides the highest chance of cure of the animal. The prognosis for mastocytoma may vary according to its grading and clinical factors, as well as immunohistochemical factors, which have great prognostic relevance but are not yet considered routine. This paper reports the case of a canine with a manifestation of a nodule at 9 months of age. Surgical excision was performed, and the sample was sent for histopathological evaluation and later, immunohistochemistry. The tumor was diagnosed as a mast cell tumor and classified as low grade by Kiupel grading, and grade II by Patnaik grading, and manifested a c-Kit II pattern and proliferation marker Ki -67 of 4 on immunohistochemistry examination. A metronomic chemotherapy protocol was performed with the use of chlorambucil 4mg / m² associated with prednisone 1mg / kg, reaching 60 days free of any signs of the disease, and being discharged from cancer, remaining only in follow-up. The occurrence of cases of malignant neoplasms in animals of early age is worrying and requires further study.