Solitary skin lesions with histopathologic features of early mycosis fungoides.

Mycosis fungoides (MF) is a cutaneous T-cell lymphoma that usually begins with cutaneous patches that evolve into plaques and tumors. A few recent reports describe a solitary variant of MF distinct from localized pagetoid reticulosis, a disease in which solitary verrucous lesions occur on acral skin. Solitary skin lesions with some of the histopathologic features of MF rarely occur during treatment with several drugs, especially antidepressants or antihistamines. We analyzed the clinicopathologic features of 20 patients with solitary skin lesions showing histopathologic features of patch- or early plaque-stage MF. Eight men and 12 women (mean age 50.6, range 23-82, median 49) had solitary, small erythematous patches or plaques located on the trunk (16 cases, 6 of them on the breast), upper extremities (3 cases), and inguinal region (1 case). Ten patients were treated with one or more drugs; only two of them received antidepressants or antihistamines. Histopathologic examination revealed in all cases a band-like infiltrate in the upper dermis, frequently with epidermotropism of solitary lymphocytes. Atypical lymphocytes were present in a minority of cases. Immunohistology showed a predominance of CD3+ T lymphocytes, in most cases admixed with clusters of CD20+ B-cells. Only a small proportion of the infiltrate was CD8+. Molecular analysis of the rearrangement of the T-cell receptor genes was performed in 16 cases using the polymerase chain reaction (PCR) technique and revealed a monoclonal band in 8 of them. After surgical excision, 2/14 patients had a recurrence near the surgical scar. In 18 patients with complete follow-up data, no evidence of "classic" MF could be observed after a mean follow-up of 31.9 months. Solitary skin lesions with the histopathologic features of MF can be considered as a distinct clinicopathologic entity, probably representing a solitary variant of mycosis fungoides.