CUTANEOUS MAST-CELL TUMORS IN A LION (PANTHERA LEO) - A LIGHT AND TRANSMISSION ELECTRON-MICROSCOPIC STUDY

Cutaneous mast cell tumours of a 16-year-old female Indian lion (Panth era leo) were studied histologically and ultrastructurally. The prolif eration index detected with an antibody against the nuclear antigen Ki -67 was 16.5%. A cytochemical test for chymase activity was negative. Mast cell tumours are well known in domestic animals and in cats are o f two distinct histological types. The present paper is the first repo rt of poorly differentiated cutaneous mast cell tumours in a lion. In their histological and ultrastructural appearance, and in their lack o f chymase activity, the neoplastic mast cells resembled tumour mast ce lls in cats. (C) 1995 Academic Press Limited