Aspectos clínico-patológicos e terapêuticos de melanomas subungueal metastático e cutâneo em dois cães diagnosticados no Hospital Escolar Veterinário

Abstract

Melanoma is a malignant neoplasm originating from melanocytes and is frequently diagnosed in domestic animals such as dogs, cats, horses and also in wild terrestrial and marine animals, including humans. The neoplasm affects middle-aged to elderly animals, with no sexual predilection, with the highest incidence in hyperpigmented breeds. It has a poor prognosis, as it develops in an aggressive, invasive and metastatic manner, which is reflected in the short survival time of these animals. The aim of this study was to describe the clinical-pathological and therapeutic aspects of metastatic subungual and cutaneous melanomas in two dogs diagnosed at the Veterinary Teaching Hospital. Two intact males of defined breeds were selected, patient 1 (P1) being a 10-year-old Rottweiler, with a foul-smelling wound on the 3rd toe of the left pelvic limb, with a split nail and bleeding, with signs of pain on palpation and lameness for a week. Patient 2 (P2) was a 9-year-old Bullmastiff with a soft, black nodule measuring 5 cm in diameter on the right trunk of the thoracic region for three weeks. The hematologic examination revealed no abnormalities. The presumptive diagnoses were a lesion on the digit with subsequent loss of the nail and secondary bacterial infection for P1 and cutaneous melanoma for P2. In both patients, the treatment performed was surgical excision. The surgically removed specimens were sent to the Pathological Anatomy Section (SAP) for histopathological diagnosis. Forty-five days after surgery, due to the worsening of the clinical condition and poor prognosis, P1 was euthanized and the cadaver sent to SAP for post-mortem examination. The treatment proved effective in P2, who showed no signs of tumor recurrence. The results of the histopathological examination revealed the following definitive diagnoses: P1: metastatic subungual melanoma, malignant epithelioid, melanic, stage IV with metastases to the superficial inguinal lymph node, lung, liver, kidneys, spleen and thoracic and abdominal cavities. P2: cutaneous melanoma, epithelioid, melanic, stage II and reserved prognosis. P1 presented a malignant neoplasm and short survival time due to late diagnosis, and metastases to regional lymph nodes and several organs. Clinicians should consider melanoma in the differential diagnosis of blackish nodules on the skin. Early diagnosis of melanoma is essential for successful treatment.(TRADUÇAO NOSSA)