Hypopigmented Junctional BAP1-Inactivated Melanocytoma: A Paradigm Shift

Since their original description by Wiesner et al., the spectrum of clinical, histopathologic, and molecular findings of BAP1 (BRCA1-associated protein 1)-inactivated melanocytomas has been more fully characterized. Herein, we report an exceptional presentation of multiple junctional melanocytic BAP1-inactivated melanocytomas with a clinically hypopigmented appearance in a patient. Targeted DNA sequencing demonstrated the same BAP1 frameshift mutation (BAP1 p.R59f) in three different lesions. One of the specimens also displayed two truncating mutations in NF1 (NF1 p.Q129* and NF1 p.Q1801*) at 8%-9% mutant allele frequency. To our knowledge, BIM confined entirely to the epidermis, and multiple BIMs presenting in hypopigmented fashion have not been widely reported previously.