CD34-reactive fibrous papule of the nose.

In human skin, the CD34 antigen is expressed on endothelium, periadnexal cells, and a population of reticular dermal interstitial cells. CD34 expression is characteristic of dermatofibrosarcoma protuberans and several other neoplasms, but not of typical fibrous papules of the nose. We describe a 16-year-old white girl with a slowly growing papule on the nose. Histopathology showed a dermal tumor with a superficial component of branched, thin-walled blood vessels and a deeper component of benign-appearing, spindle-shaped cells. These cells uniformly and strongly expressed CD34, but not factor XIIIa or markers of melanocytic, neural, muscular, vascular, or histiocytic differentiation. We consider this lesion a CD34-reactive fibrous papule. This benign tumor must be clearly distinguished from dermatofibrosarcoma protuberans, which also is composed of bundles of CD34-reactive spindle-shaped cells in most cases but has locally aggressive behavior.