Combined folliculotropic/syringotropic cutaneous T-cell lymphoma without epidermal involvement: report of 2 cases and pathogenic implications.

Exclusive involvement of skin appendages in cutaneous T-cell lymphoma (CTCL) is rare, poses significant problems in diagnosis, and may provide insight into mechanisms of T-cell epitheliotropism. We report 2 cases of combined adnexal (folliculotropic/syringotropic) CTCL in which lesions developed only in chronically sun-damaged skin. Although the epidermal layer in both cases was devoid histologically of significant epidermotropism, immunohistochemistry and polymerase chain reaction analyses of deeper samples that included involved adnexae confirmed aberrant antigen expression (dominant CD4 populations with apparent loss of CD7 and/or CD5) and T cell clonality, respectively. It is diagnostically important to recognize adnexal CTCL as a disorder that may be clinically and histologically protean. Additionally, its occurrence in sun-damaged skin in some patients may provide insight into mechanisms of selective epitheliotropism by malignant T cells.