Derm Dx: A blue-black nodule on the hand

A 33-year-old Malaysian woman requests removal of a growth on her right hand. The lesion has been present for several years and is asymptomatic but unsightly. She states that an older brother has a similar lesion. Examination reveals an 0.8-cm dome-shaped, blue-black nodule of the affected area. Axillary lymph nodes are nonpalpable, and full body skin examination is otherwise unremarkable.