Dermal thymus: case report and review of the literature.

An aberrant thymus is not uncommon; it is usually located in the subcutaneous tissue and attaches to deeper structures, but it rarely occurs within the dermis (dermal thymus). We report on an 8-month-old male infant with a dermal thymus. He was born with a skin tumor on the right side of the neck, located just over the sternocleidomastoid muscle. The tumor was soft, dark red, and elevated. It measured 10 by 21 mm in diameter. The surface was erosive and partially covered with crust. The infant also had a unilateral cleft lip and a deformity of the bilateral auricles. Because of recurrent episodes of infection, the tumor was resected and histologically diagnosed as a dermal thymus.