Pulmonary Plasmacytoma - Rare Occurrence in Multiple Myeloma: Case Presentation and Short Review of the Literature.

Multiple myeloma is a hematological malignancy mostly diagnosed in the elderly. It is characterized by a chronic evolution with alternating periods of remission and relapses. Plasmacytoma, a tumor comprised of monoclonal plasma cells, is a typical finding in multiple myeloma patients, being more frequently observed during relapses. The most involved sites are bones, kidneys, liver, skin, ear, nose and throat. Extramedullary lung plasmacytomas are a rare presentation, with an incidence of well under 5% of all plasmacytomas. The clinical manifestations are heterogeneous and depend on the affected site. Differentiating plasmacytoma from other pathologies can be challenging, with the diagnosis being established via tumor biopsy. The presence of plasmacytoma is associated with poor prognosis and is a marker of rapid disease progression. We report the case of a 63-year-old patient diagnosed with IgA lambda multiple myeloma, stage IIIB Salmon-Durie complicated by lung plasmacytoma identified in the setting of relapse. Despite undergoing treatment, the disease exhibited an aggressive course, rapidly progressive towards death. The case underlines the rarity of pulmonary plasmacytoma and the diagnostic challenges.