Condylomata acuminata.

A 5-year-old Thoroughbred chestnut mare was presented because of multiple lesions noticed for approximately one year over the vulva and ther perianal areas. Clinically, there were moist warts that stood out because of their whitish color which contrasted strikingly with the surrounding, normally pigmented, uninvolved skin (Fig. 1). Repeated topical applications of 20% podophyllin in 95% ethyl alcohol produced rapid involution. Histopathologically, marked acanthosis, numerous mitoses, prominently vacuolated epidermal cells and a chronic dermal inflammatory infiltrate were seen (Figs. 2, 3, and 4). Interestingly, melanin in the basal cell layer was not visible in the lesions, but was very apparent in the normal epidermis at the edges of the lesions. Thus the contrast between the affected and the non-affected skin was also strikingly microscopically (Fig. 2 arrows).