The clinical, gross and microscopical features of a granulosa cell tumour in the ovary of a 2-year-old cat are described. This is a rare tumour in cats, moreover because of the animal’s age. It was diagnosed clinically by ultrasound examination. The tumour, a cystic mass in the region of the left ovary, metastasized to the epiplon and lungs. Tumour cells expressed vimentin and were arranged in a diffuse sarcomatous pattern, supported by a fine fibrovascular stroma. The presence of hair loss and repeated oestrus as clinical signs are indicative of orthoendocrine paraneoplastic syndrome, due to excessive oestrogen stimulation. This tumour should be considered in the differential diagnosis of behavioural disturbances in female cats.
Granulosa cell tumour; Ovary; Cats; Immunohistochemistry; Paraneoplastic syndromes