Clear cell tumors of the skin.

Clear cell tumors of the skin represent a heterogeneous group of lesions of diverse histogenesis that share as their common denominator the presence of cells containing abundant clear cytoplasm. The phenomenon of cytoplasmic clearing may be observed focally or represent the dominant feature in a variety of tumors originating from the epidermis or in tumors within the dermis showing well-defined features of eccrine, sebaceous, and follicular lines of differentiation. In addition to the aforementioned conditions, melanocytic lesions derived from the epidermis characterized by a prominent or predominant clear cell component as well as metastases to the skin from clear cell tumors of internal organs may enter the differential diagnosis and will also be discussed. Because of the superficial resemblance imparted by this distinctive cytologic feature, these lesions may occasionally pose difficulties for diagnosis. A review of the various entities that comprise this group of lesions is presented, with emphasis on their distinguishing histopathologic features and differential diagnosis.