Naturally Occurring Infectious Fibroma in the Domestic Rabbit

Abstract

Infectious fibromas developed in eight domestic rabbits that were all kept in outside cages. Each rabbit had a single cutaneous tumor. Six of these tumors, which were studied by light microscopy, consisted of tumor cells resembling fibroblasts and large areas of inflammation. The overlying epidermis was hyperplastic and contained easily recognizable intracytoplasmic inclusion bodies. Inclusion bodies were also in subepithelial fibroma cells. Electron microscopy of three of these tumors revealed typical pox-virus inclusions, sites of viral replication, maturation, and mature particles in epithelial cells of the epidermis and in subepithelial tumor cells. Virus was not seen in inflammatory cells or leukocytes within vascular channels.