Trichoblastoma in a dog: A case report

A five-year-old male Labrador with a mass in the ear pinna was brought to the Madras Veterinary College Teaching Hospital, Chennai. On clinical examination, the mass appeared pale pink in colour, firm in consistency with discrete lobulation and measured 3 cm in diameter. Haemato-biochemical studies and imaging assessments revealed no abnormalities while cytological findings of the mass showed basal epithelial cells arranged in a row which was suggestive of trichoblastoma. Histopathological examination revealed cuboidal to elongated neoplastic cells with pale eosinophilic cytoplasm arranged in ribbon pattern, supported by fibrovascular stroma which was confirmative of trichoblastoma. Immunohistochemical studies also confirmed the tumour by showing positive expression of cytokeratin. Based on the laboratory findings, the tumour was identified as trichoblastoma.