Abstract
A 49-year-old woman presented with a subcutaneous mass on her right elbow that had enlarged gradually over the course of 1 year. Her medical history was unremarkable. Histologically, there were nodular infiltrates of mature plasma cells in the dermis and subcutis and several germinal centers with infiltrate of lymphoid cells. Immunohistochemistry revealed plasmacytoid cells positive for CD79a, CD138, Bcl-2 and negative for CD10, CD20. Germinal centers showed a CD10+, CD20+, CD21+ phenotype. Plasmacytoid cells showed monotypic expression of immunoglobulin light chain. Positron emission tomography and bone marrow biopsy were normal. She was diagnosed with primary cutaneous extranodal marginal zone lymphoma with prominent plasma cell differentiation. The residual mass on her right elbow was excised, and subsequently radiotherapy was performed. There has been no sign of recurrence after 1 year.[Skin Cancer (Japan) 2013 ; 28 : 169-173]
