Extramedullary manifestation of multiple myeloma presenting as infraorbital swelling: a rare case report

Plasma cells originate from B lymphocytes and play a vital role in immune defence by producing immunoglobulins. Malignant transformation of these cells results in plasma cell neoplasms, of which multiple myeloma (MM) is the most common. MM typically involves diffuse infiltration of the bone marrow. Facial swellings are frequently encountered in otorhinolaryngology practice and are usually attributed to congenital, inflammatory, vascular, or neoplastic causes. However, facial involvement due to multiple myeloma is exceedingly rare. We report a case of infraorbital facial swelling that developed three years after the initial diagnosis of multiple myeloma. The patient presented with a progressively enlarging facial mass, raising suspicion of extramedullary relapse of underlying MM. A comprehensive evaluation, including detailed clinical history, physical examination, imaging studies, and histopathological analysis, was crucial in establishing the diagnosis and guiding management. This case highlights the importance of considering MM in the differential diagnosis of unexplained facial swelling, particularly in patients with a known history of plasma cell neoplasms. Early recognition by primary care physicians and otorhinolaryngologists is essential for timely diagnosis and appropriate multidisciplinary management.