Abstract
Cylindroma, a benign skin appendage tumor, mostly occurs in the head and neck region. They present as pink to purple, smooth-surfaced, solitary or multiple nodular lesions, mostly affecting middle-aged and elderly women. A clinical diagnosis of cylindroma is unusual but must be considered clinically. We report an unusual case of solitary benign dermal cylindroma that occurred in an uncommon site in a 54-year-old female. She came with complaints of painful swelling on the left side of her chest wall for six months. Histopathological examination of the mass revealed a well-defined tumor composed of nests and islands of a dual population of tumor cells surrounded by pink basement membrane-like material. These nests of cells are arranged in a "jigsaw" puzzle fashion, which is typical of cutaneous cylindroma. The thick pink material surrounding the epithelial cell islands is periodic acid Schiff stain (PAS) positive.