Subcutaneous Papillomatous Cysts Produced by Bovine Papilloma Virus

Summary

Papillomatous cysts developed in calves when autologous skin which had been bathed in a suspension of bovine papilloma virus (BPV) was implanted subcutaneously, or when either an area of skin inoculated with BPV or a recently developed cutaneous papilloma was buried subcutaneously. Virus-stimulated allogeneic skin implants or papilloma transplants from other calves failed to produce cysts as did non-virus-stimulated autologous skin. The cysts first developed as small cavities lined with squamous epithelium surrounded by a fibromatous capsule. By 4 months there was extensive papillomatous proliferation of the epithelium and the cysts were quite large. Scattered areas of coagulation necrosis in the epithelium began to appear at 6 months in a few cysts. By 21 months, the lining epithelium was thin and no longer hyperplastic and in someareas there was no epithelium. The content of the cysts was initially a thick, dry, caseous material that later became fluid and contained a few large clumps of keratinized epithelium. BPV and antibody to the virus were found in the cysts. When the papillomatous lining of cysts was exposed to the exterior by surgery, a typical cutaneous fibropapilloma developed.