AN UNUSUAL VASCULAR TUMOR IN A FISCHER’S LOVEBIRD (AGAPORNIS FISCHERI)

A 6 year old female Fischer’s lovebird (Agapornis fischeri) was conducted for necropsy, with a cutaneous mass on the neck, 3,5 cm in diameter, yelding and with blood content. Histopathological findings showed a neoplasm characterized by proliferation of vascular endothelial cells. The histology of the mass revealed a multinodular, focally infiltrating tumor. Deeper dermal nodules were made of spindle cells forming vascular slits reminescent of the histology seen in Kaposi’s sarcoma. More superficially located dermal nodules consisted of small blood vessels, with histology resembling capillary hemangioma. The spindle cells and capillaries were strongly positive for vimentin, endothelial cell marker CD31, and negative for sarcomeric α-smooth muscle actin (α-SMA). Intravascular platelet trapping and periodic acid-Schiff (PAS)-positive hyaline globules were also observed. Differential diagnosis included Kaposi’s sarcoma, capillary haemangioma, spindle cells haemangioendothelioma, and epithelioid haemangioendothelioma. Based on morphological and immunohistochemical findings, the tumor was diagnosed as a cutaneous Kaposiform haemangioendothelioma, a rare, low-grade malignant vascular neoplasm. In this case, parrot death occurred for a severe glomerular amyloidosis, associated with chronic widespread tubular nephrosis. Other organs showed no abnormalities. To the best of our knowledge, this unusual case is the third report of Kaposiform hemangioendothelioma in any non-human animal species, the first described in a psittacine bird.