Am J Dermatopathol 2021 Jun 2. Epub 2021 Jun 2.
Department of Pathology, Lisbon Institute of Oncology, Lisbon, Portugal; Department of Dermatology, Kempf and Pfaltz Histological Diagnostics, University Hospital Zurich, Zurich, Switzerland; Kempf und Pfaltz Histologische Diagnostik, Zurich, Switzerland; Dermatopathology Friedrichshafen, Friedrichshafen, Germany; and Department of Pathology, St Thomas' Hospital, London, United Kingdom.
Abstract: Primary extramedullary plasmacytoma is rare monoclonal proliferation of plasma cells, which arise in various nonosseous anatomic locations without detectable underlying systemic disease. Historically, cutaneous infiltrates rich in mature neoplastic plasma cells have fallen into one of the following categories, plasmacytoma, lymphoplasmacytic lymphoma, and marginal zone lymphoma, which included immunocytoma. Since 2005, each of these was subsumed under the marginal zone lymphoma umbrella, largely on the basis of acknowledged diagnostic difficulties in some of these cases. Read More