Primary cutaneous T-cell lymphoma localized to the lower leg: a distinct, locally aggressive cutaneous T-cell lymphoma.

BACKGROUND Distinct categories of skin lymphoma with preferential site localization and unique clinical behavior, including leg-type primary cutaneous diffuse large B-cell lymphoma, have recently been described. Although these entities are rare, they exhibit reproducible clinicopathologic features, and their recognition may allow more appropriate treatment protocols. OBSERVATIONS We describe the distinctive clinicopathologic features that were observed in 3 patients with an unusual variant of primary cutaneous T-cell lymphoma. All cases originated on the legs of elderly patients and exhibited a locally aggressive clinical behavior with relatively rapid relapses after radiotherapy and resistance to other therapies. Histologically, dense dermal-centered infiltrates of atypical, variably sized mature helper T cells were identified. One patient died of progressive disease. CONCLUSIONS Rare cases of primary cutaneous lymphomas do not necessarily fit current criteria for a standard diagnostic category but may represent unique clinicopathologic entities, such as primary cutaneous T-cell lymphoma localized to the lower leg. It is important to be able to identify these unusual lymphoma variants for prognosis and adequate treatment. The aggressive nature of lymphomas preferentially localized on the lower extremities may not be restricted to B-cell or cytotoxic neoplasms.