Extraosseous Plasmacytomas: A Radiologist's Perspective-A Narrative Review of the Literature

Extraosseous plasmacytomas (EPs) are rare neoplasms originating from plasma cells, often associated with multiple myeloma. EPs are classified into three subtypes: extramedullary myeloma, solitary extramedullary plasmacytoma (SEP), and multiple solitary plasmacytomas. They can manifest in various anatomical sites, including the lung, mediastinum, breast, liver, pancreas, stomach, mesentery, kidney, small and large bowel, testis, and soft tissue. Despite their rarity, EPs present a diagnostic challenge due to their non-specific imaging appearances, which can mimic other neoplastic and inflammatory conditions. This review aims to describe the radiographic features of EPs in the chest, abdomen, and pelvis based on a thorough analysis of the existing literature. While imaging plays a crucial role in the detection and characterization of EPs, histological confirmation is necessary to differentiate them from other neoplastic entities. The review underscores the importance of considering EPs in the differential diagnosis, particularly in patients with a history of multiple myeloma. Understanding the imaging characteristics of EPs is essential for accurate diagnosis and appropriate management. Early imaging is crucial in these patients to exclude the possibility of EP, as timely diagnosis can significantly impact patient outcomes.