Basal cell carcinoma metastatic to parotid gland

Metastasis from basal cell carcinoma of the skin is very rare with cases being documented in the lymph nodes, lung, bone and parotid gland. The main histopathological differential diagnosis is the locally arising basal cell adenocarcinoma from which it is difficult to distinguish by morphology and routine immunohistochemistry. Approximately 85 % of all reported metastatic basal cell carcinomas arise in the head and neck region. Here we present a case of basal cell carcinoma of the skin of the left lateral canthus of the eye which metastasized to the intraparotid lymph nodes with infiltration of the adjacent parotid parenchyma. More awareness and vigilance is required on the part of the reporting pathologist to consider metastasis in the presence of a parotid tumour. Features favouring metastasis include history of primary cutaneous basal cell carcinoma, histological similarity to the primary lesion and absence of any demonstrable direct extension from the skin lesion. We also review the literature on metastatic basal cell carcinoma and discuss the need for adequate follow up in high risk patients.