Loss of BAP1 Expression in Basal Cell Carcinomas in Patients With Germline BAP1 Mutations

Patients with heterozygous germline mutations in BRCA1-associated protein 1 (BAP1), a tumor suppressor gene, develop a tumor predisposition syndrome (OMIM 614327) with increased risk of uveal and cutaneous melanomas, cutaneous atypical and epithelioid melanocytic lesions, lung adenocarcinoma, clear cell renal cell carcinoma, and other tumors. Early recognition of this syndrome is of clinical importance. In addition, screening for BAP1 mutation, loss, and inactivation by performing BAP1 immunohistochemistry on cutaneous lesions would be a simple method for screening patients suspected of having germline BAP1 mutations.

We investigated BAP1 expression in seven basal cell carcinomas (BCCs) in two patients with germline BAP1 mutation and a family history of uveal melanoma. Six lesions were from the head and neck region and one from the shoulder. Thirty-one sporadic BCCs were included as controls.

All seven BCCs in the patients with germline BAP1 mutations exhibited loss of BAP1 nuclear staining, while 30 (97%) of 31 sporadic BCCs exhibited positive BAP1 nuclear staining.

Loss of BAP1 expression could be associated with the development of BCC in patients with germline BAP1 mutations. These results suggest that BCC may be a component of the expanding category of tumors associated with this syndrome.