The patient’s son (IV.1, Figure 1A) with a previous history of
an early age dysplastic nevus detected at age 17 was subsequently
diagnosed with another dysplastic nevus at age 26.
Dermatologic evaluation with biopsy demonstrated compound
Spitz proliferation of melanocytes; these histologic
features raised concern for loss of expression of the BAP1gene
(9). IHC staining of the dysplastic nevi confirmed an absence
of BAP1 protein. Within this same time period, the proband’s
other son (IV.2, Figure 1A) developed early age
melanoma on his knee for which IHC assessment also revealed
absent BAP1 protein expression. Dysplastic nevi and
melanoma are less common among individuals during the first
three decades of life compared with older age cohorts (17,18).
The early age of these dermatologic diagnoses together with
lack of BAP1 protein expression in the tumor specimens
created suspicion for an inherited germline mutation of BAP1;
moreover, the constellation of cancer diagnoses within the
family raised the possibility of a novel manifestation of the BAP1
tumor predisposition syndrome.