Primary cutaneous spindle cell B-cell lymphoma with multiple figurate erythema-like manifestation.

We report a 68-year-old Korean man presenting with asymptomatic erythematous polycyclic annular firm plaques on his back that spread to the right shoulder. Histopathologic examination showed dense, diffuse infiltrates involving the entire dermis, consisting of atypical lymphocytes with many centrocytes and a few centroblasts. Spindle-shaped cells with elongated, twisted nuclei containing dispersed chromatin were also seen. Immunohistochemical analysis showed that all of the cells were strongly positive for CD20, CD21, CD79a and CD45, while they were negative for CD3, CD5, CD10, CD23, CD35, CD43, CD45RO and CD68. The spindle cells were also negative for smooth-muscle actin, desmin, S-100 and CD34. They consistently expressed nuclear bcl-6, but did not express bcl-2, multiple myeloma-1 and p16. We diagnosed him with primary cutaneous spindle cell B-cell lymphoma (PCSBCL) and treated him with six cycles of cyclophosphamide, adriamycin, vincristine, prednisone and rituximab (R-CHOP) chemotherapy; his skin lesions disappeared completely. Immunohistochemical profiles suggest that PCSBCL is a variant of primary cutaneous follicle center lymphoma.