Abstract Introduction Extramedullary plasmacytomas (EMP) are rare, accounting for only 3% of all plasma cell malignancies, and typically arise in the soft tissues of the upper respiratory tract. We present an exceedingly rare case of a Primary Pulmonary Plasmacytoma (PPP), a notable subtype of EMP, which was definitively diagnosed via cryobiopsy of multiple nodules in the lung. Case A 59-year-old non-smoking male with hereditary hemochromatosis presented to pulmonology clinic for evaluation of bilateral pulmonary nodules. CT Chest scans demonstrated persistent mediastinal lymphadenopathy, a stable RML nodule, and multiple enlarging left lobe nodules. Notably, subsequent PET imaging revealed no avid nodules, adding to the diagnostic uncertainty. Given the progression, the patient underwent robotic bronchoscopy with transbronchial needle aspiration and cryobiopsies, as well as endobronchial ultrasound biopsy of lymph nodes. Histopathology of the nodules confirmed a lambda-predominant CD138-positive plasma cell neoplasm. Mediastinal lymph nodes and all infectious cultures were negative, securing the diagnosis of this rare extramedullary malignancy. Discussion As seen in this patient, the diagnosis of extramedullary plasmacytoma requires an isolated plasma cell tumor in the absence of other findings of multiple myeloma, including bone marrow involvement, lytic lesions, or evidence of end-organ damage attributable to a lymphoproliferative disorder. Presentation in the lower respiratory tract is rare and may mimic lung cancer or infection, necessitating a comprehensive work-up and high clinical suspicion for accurate diagnosis. Radiation therapy is the first line treatment and the overall prognosis is good, with low rates of recurrence and a 10-15% estimated rate of progression to multiple myeloma. Conclusion Although pulmonary plasmacytoma is a rare presentation of plasma cell neoplasm, it should be considered in the differential in patients with multiple lung nodules even in the absence of other evidence of a lymphoproliferative disorder. This abstract is funded by: None
Moore et al. (Fri,) studied this question.