Primary centroblastic/centrocytic lymphoma of the skin. Detection of B-cell monoclonality by polymerase chain reaction.

A 60-year-old woman was examined for erythematous plaques and nodules on the back that had appeared 1 year earlier. Histologic examination of a skin biopsy specimen showed a dense, diffuse infiltrate throughout the dermis and subcutis, composed mainly of centroblasts and centrocytes. Immunohistochemistry confirmed positivity of the neoplastic cells for L26 (CD20) and LN1 (CDw75) antibodies and negativity for UCHL1 (CD45RO), polyclonal anti-CD3, anti-kappa, and anti-lambda antibodies. Polymerase chain reaction (PCR) analysis on paraffin-embedded tissue sections of the cutaneous lesion showed immunoglobulin heavy-chain (VDJ) and kappa-chain gene rearrangement. Routine laboratory studies were within normal limits. The staging workup of the patient (bone marrow biopsy, computed tomographic scans of the chest and abdomen) showed no abnormalities. Based on clinicopathologic findings and molecular analysis, a diagnosis of primary cutaneous centroblastic/centrocytic lymphoma was made. The patient was treated with intra- and perilesionally administered recombinant interferon alpha-2a (3 x 10(6) IU) three times a week for 2 months. Complete response was achieved, and no evidence of recurrence has been observed after 18 months of follow-up.