Bullous pilomatricoma: a stage in transition to secondary anetoderma?

Pilomatricoma is an uncommon hamartomatous tumor of the hair matrix. Bullous and anetodermic changes over pilomatricoma are rare. We report an 18-year-old male with an asymptomatic nodule with overlying cystic changes on the left arm of 6-month duration with clinical and histological features of both bullous and anetodermic modifications. We also reviewed the associated literature to conclude that there is sufficient overlap in these two entities. Both variants show a bullous or pseudobullous appearance clinically and loss of elastin, sparse collagen bundles separated by intense edema, and dilated lymphatics/blood vessels in the dermis overlying the tumor mass histologically. We therefore propose that bullous, pseudoampullary, anetodermic, and lymphangiectatic forms should be considered as synonymous or transitional to the ultimate scar-like anetodermic appearance.