Metastatic Basal Cell Carcinoma: A Biological Continuum of Basal Cell Carcinoma?

Basal cell carcinoma (BCC) accounts for 80% of all nonmelanoma skin cancers. Its metastasis is extremely rare, ranging between 0.0028 and 0.55 of all BCC cases. The usual metastasis to lymph nodes, lungs, bones, or skin is from the primary tumor situated in the head and neck region in nearly 85% cases. A 69-year-old male developed progressively increasing multiple, fleshy, indurated, and at places pigmented noduloulcerative plaques over back, chest, and left axillary area 4 years after wide surgical excision of a pathologically diagnosed basal cell carcinoma. The recurrence was diagnosed as infiltrative BCC and found metastasizing to skin, soft tissue and muscles, and pretracheal and axillary lymph nodes. Three cycles of chemotherapy comprising intravenous cisplatin (50？mg) and 5-florouracil (5-FU, 750？mg) on 2 consecutive days and repeated at every 21 days were effective. As it remains unclear whether metastatic BCC is itself a separate subset of basal cell carcinoma, we feel that early BCC localized at any site perhaps constitutes a biological continuum that may ultimately manifest with metastasis in some individuals and should be evaluated as such. Long-standing BCC is itself potentially at risk of recurrence/dissemination; it is imperative to diagnose and appropriately treat all BCC lesions at the earliest. 1. Introduction Basal cell carcinoma (BCC), a slowly progressive and poorly metastasizing skin cancer with propensity to be locally destructive, accounts for almost 80% of all nonmelanoma skin cancers worldwide [1]. Despite such a high prevalence its metastasis is extremely rare ranging between 0.0028 and 0.55 of all BCC cases [2]. Almost 85% of metastatic BCC arise from primary lesions in the head and neck region and is less frequent from BCC over back and extremities [3]. Metastatic BCC typically occurs in middle-aged men having BCC of long duration, and the spread in order of frequency is usually to lymph nodes, lungs, bones, skin, or to other sites. Giant BCC, a tumor of more than 5？cm at its largest diameter, is its rare and aggressive form and occurs commonly on trunk [4]. However, in a metastatic BCC the primary cutaneous tumor must have distant metastatic lesions with histopathologic features identical to the primary tumor [5]. The described case is of metastatic BCC over the back with recurrence 4 years after excision and metastasis to regional lymph nodes, skin, soft tissues and muscles. 2. Case Report This 69-year-old male presented with multiple noduloulcerative lesions over upper trunk. History revealed that he had a nodule over his