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A 30-year-old palomino Standardbred horse was seen with a persistent penile squamous cell carcinoma. After failure using multiple treatments, surgical removal was successfully carried out under local anesthesia using Mohs micrographically controlled surgery. Subsequent examination of the malignant tissue identified bovine papillomavirus exclusively within the nuclei and cytoplasm of tumor cells. The use of Mohs surgery would appear to be useful as an effective, precisely controlled treatment for managing genital squamous cell carcinoma in equine subjects. The presence of papillomavirus within tumor cells would suggest the possibility of causation by an oncogenic papilloma virus and would indicate that careful monitoring of the surgical site should be performed.

The mainstay of therapy for pyoderma gangrenosum has been corticosteroids, but many patients respond poorly. During the past 2 years we have treated seven patients who had pyoderma gangrenosum with cyclosporine after their condition proved resistant to conventional therapy. No evidence of permanent toxicity from cyclosporine was detected and treatment with other immunosuppressive agents was discontinued in five of seven cases. Tuberculosis was reactivated in one patient. Three patients had a remission, three had an intermediate response, and one did not respond. These results indicate that cyclosporine is useful in the treatment of patients with refractory pyoderma gangrenosum and suggest an immune mechanism in the pathogenesis of this disorder.