Malignant basal cell tumor
Strict diagnostic criteria should be applied for this rare murine tumor. Sheets of basaloid tumor cells with a well formed peripheral palisade and numerous apoptotic cells and mitotic figures should be present. Invasion of individual tumor nests is a supportive feature. Most tumors of this type do not appear to arise from the follicular epithelium in mice and do not the extensive follicular differentiation of the basaloid follicular neoplasms listed below. The relationship of malignant basal cell tumor and basaloid follicular neoplasms with human basal cell carcinomas is not well understood at present.