Track

Abstract

Basal cell carcinoma (BCC) is the most common type of skin cancer and tends to affect sun exposed skin of middle-aged and elderly patients. BCC is a biphasic follicular tumor that seems to recapitulate a developing follicular germ as seen in fetal autopsy. The histological features of basal cell carcinoma are well known to pathologists: basaloid cells, fibromyxoid stroma, clefting, peripheral palisading. In general, patients can be justifiably re-assured that their BCC will not be life threatening. The finding of basal cell carcinoma metastatic to bone is extraordinary and herein we present such a patient. A 64 year old male had a history of a large infiltrative basal cell carcinoma involving the right posterior shoulder, which recurred extensively after surgical excision. A CT scan performed for screening purposes in the context of a significant smoking history showed osseous abnormalities. Subsequent biopsy of left iliac crest revealed an infiltrative carcinoma with palisaded basaloid cytology and being morphologically identically to the BCC on his shoulder. Gene expression molecular cancer typing on the bone specimen also supported a 96% probability of basal cell carcinoma. The patient has demonstrated slow progression on vismodegib and cemiplimab over three years. Osseous involvement by BCC is extraordinary.