Rare MM Case Underscores Need to Consider Differential Diagnoses

A patient with a history of hypertension, hyperlipidemia, and substance use disorder, as well as a family history of lung cancer, complained of chest pain and discomfort, in a case that highlights the importance of the differential diagnosis process in the multiple myeloma (MM) space.

The 50-year-old woman initially presented with an apical lung mass—a Pancoast tumor—but testing showed metastasis to 6 axillary lymph nodes (LNs) and extensive bony involvement in the right second rib, eighth and ninth ribs, right scapula, iliac bones, left ischium, sacrum, coccyx, and thoracic and lumbar vertebra indicating a potential case of MM.

Typical presentation of MM involves “a neoplastic proliferation of immunoglobulin-producing plasma cells with clinical features resulting from infiltration of plasma cells into bones and other organs,” the report authors noted. They published their findings in Radiology Case Reports, noting that very few cases of this patient’s MM presentation have been reported.

Most apical lung masses have their origins in pulmonary tissues, not extrapulmonary sources, according to the report. The patient in this case had normal vitals, calcium and albumin levels, and kidney function, but tests showed a hemoglobin level of 9 g/dL and red cell distribution width of 19.2%, indicating anemia, and a white blood cell count of 4.1 (ref, 4.8-10.8) k/uL, indicating leucopenia.

LN biopsy results indicated presence of monocytic (kappa) plasma cells, “consistent of cell neoplasm,” but with the patient being lost to follow-up, a biopsy of the Pancoast tumor could not be performed. When she later presented with left upper thigh and right shoulder pain but no history of weakness or trauma in either area, several x-rays showed right upper lobe mass-like opacity; lytic, permeative lesion within the proximal and midhumoral diaphysis and proximal pathologic compression fracture; and right lung base and lateral right upper lobe opacities.

A subsequent chest CT was the first sign of potential MM, due to the presence of diffuse lytic lesions “throughout the visualized osseous structures compatible with history of multiple myeloma.” Morphologic and immunophenotypic findings, also consistent with MM, were seen upon bone marrow biopsy, and the patient began chemotherapy of high-dose dexamethasone, cyclophosphamide, and bortezomib, the standard first-line treatment for newly diagnosed MM.

What makes this patient’s MM presentation so rare, the case report authors noted, is its extramedullary plasmacytomas, “which account for [less than] 5% of MM manifestations.” MM is already considered a rare cancer, they added, representing approximately 1.8% of new cancer diagnoses each year in the United States and 2% of all cancer deaths. Extramedullary presentation also has a higher risk of mortality, shortened progression-free survival, relapse, and more aggressive disease.

“Very few cases of lung involvement have been described, with fewer cases manifesting as Pancoast tumors,” the authors concluded. “Having a high index of suspicion was crucial in making this diagnosis, as early diagnosis was critical in determining the patient’s management options and prognosis.”

Reference

Okobi TJ, Gupta S, Ahmad H, et al. Apical lung mass—a rare presentation of multiple myeloma. Radiol Case Rep. 2022;17(9):2951-2955. doi:10.1016/j.radcr.2022.05.060