Malignant melanoma of the subcutaneous tissues in an umbrella cockatoo (Cacatua alba)

A 24-year-old female umbrella cockatoo (Cacatua alba) was examined because of a subcutaneous swelling of the left shoulder. Radiographs of the left wing revealed boney proliferation of the left proximal humerus. At surgery, an unencapsulated infiltrative nonpigmented mass within the subcutaneous tissue and skeletal muscle was identified overlying the left humerus. The mass was surgically excised and submitted for histologic examination; however, the cockatoo died after excision. Histologically, the mass was composed of nests and sheets of pleomorphic neoplastic cells with a high mitotic index and extensive necrosis. Rare neoplastic cells contained fine brown cytoplasmic granules that stained black with Fontana-Masson, confirming the presence of melanin pigment. The histomorphologic diagnosis was consistent with an anaplastic malignant melanoma of subcutaneous tissues.