Primary cutaneous diffuse large B-cell lymphoma, leg type (cDLBCL-LT) is a well-defined entity of cutaneous B-cell lymphoma affecting predominantly elderly patients, mostly women. The typical clinical presentation is characterized by solitary or multiple, rapidly growing plaques or tumors on 1 leg (rarely both legs).

We sought to describe a new clinical variant of cDLBCL-LT that deviates from the conventional one.

Clinical, histopathologic, phenotypical, and molecular features of 3 cases of cDLBCL-LT presenting with patches or thin plaques were reviewed (all were women, aged 60, 62, and 87 years; lesions were located on the leg in all patients).

These patients presented with patches or thin plaques that represented the first manifestation of cDLBCL-LT. All 3 patients reported a history of long-standing lesions (present for 6, 9, and 18 months, respectively). Histology revealed moderately dense, perivascular infiltrates of small lymphocytes admixed with variable numbers of large cells that were CD20⁺, Bcl-2⁺, and MUM-1⁺.

There were only a small number of cases.

We reported an unusual clinical presentation of cDLBCL-LT that deviates from the conventional one and that represents a formidable diagnostic challenge. Biopsy specimens of unusual patches/thin plaques or annular lesions should be obtained from the legs of adult patients if the lesions do not respond to conventional treatment.