CUTANEOUS MELANOCYTOMAS IN 10 YOUNG CATTLE

Ten melanocytomas from 10 cattle were diagnosed by histopathologic exa mination of biopsy specimens submitted to the Veterinary Medical Diagn ostic Laboratory, University of Missouri, between 1 January 1986 and 3 1 December 1993. One tumor was congenital; the others were first notic ed between 2 months and 2 years of age ((x) over bar = 9.9 months). Si x tumors occurred in purebred (3) or crossbred (3) Angus cattle; one t umor each occurred in a Holstein, a Shorthorn, a Simmental, and a beef calf of unrecorded breed or coat color. Five calves were female, and five were male. Five tumors occurred in truncal dermis or subcutis (th ree in abdominal skin), four occurred on a limb, and one occurred on t he jaw. Tumors varied in histologic appearance, but all were pigmented and all had few mitotic figures. Outcome was known for 8/10 cattle. I n four cattle followed for at least 1 year, the tumor did not recur af ter surgical excision. Another heifer had residual gray tissue at the tumor site after surgery but remained in the herd without regrowth of the tumor 30 months after excision. Three other calves were slaughtere d within 6 months of excision without apparent recurrence of the tumor .