Extramedullary Plasmacytoma of the Lung - Rather a Disseminated than a Localized Disease? - A Case Report of a Primary Pulmonary Plasmacytoma Showing Distinct Signs of Systemic Spread

We report a 58 years old woman presenting with an extramedullary plasma cell tumor of the lung with additional affection of lymph nodes above and underneath the diaphragm, without apparent infiltration of the bone marrow by malignant plasma cells, but evidence for a small proportion of clonal plasma cells in the FACS analysis. As the patient showed excretion of lambda light chains in the urine besides the solid manifestations on multiple sites and minimal bone marrow involvement, the systemic spread in this case was verified. This in contrast to primary extramedullary plasmacytoma (PPP) presenting as solitaire plasma cell tumors mostly occurring in the upper aerodigestive tract or extramedullary myeloma, which describes relapses or extramedullary progression of multiple myeloma emerging in various organs. We herein present all features of a, to our opinion, systemic disease by means of affection pattern, laboratory values and bone marrow infiltration. This unusual case demonstrates the presentation of an extramedullary plasma cell tumor that appeared as a PPP but showed distinct signs of dissemination as well as uncommon features such as a monoclonal component of IgM type. This example reveales, that extramedullary manifestations of plasma cell dyscrasia should be surveyed carefully as they can conceal an underlying systemic disease.