Benign cutaneous mastocytomas in two litters of Siamese kittens.

Histiocytic-like cutaneous mast cell tumors were found in related Siamese cats less than 6 months old. The 2- to 5-mm diameter tumors developed only on the head and regressed within 4 months of diagnosis. Attempts to treat 2 of 4 affected kittens with topically or parenterally administered corticosteroids did not speed tumor regression, and the cause of the tumors was not determined.