A primary cutaneous T-cell lymphoproliferative disorder. It usually presents with a solitary plaque or tumor on the face, neck, or upper trunk. Morphologically, it is composed of small to medium-sized CD4-positive, CD8-negative, and CD30-negative pleomorphic T-lymphocytes. A small number of large pleomorphic T-lymphocytes may also be present. The lymphocytic infiltrate is dermal. Focal epidermotropism and subcutaneous involvement may be present. The clinical behavior is almost always indolent and most patients present with localized disease. [from
NCI]