Plasmacytoma Presenting as Missing Rib on Chest Film: A Case Report and Review of the Literature
Terrell Caffery, MD; Matthew Foy, MD
A 33-year-old man presented to the emergency department (ED) with chief complaint of chest pain, persist- ing for approximately one year. Chest X-ray revealed he was missing the right posterior fifth rib. Physical examination showed no surgical scars, and he reported no history of chest trauma. A CT of his chest demon- strated a mass involving the posterior aspect of the right fifth rib, and subsequent biopsy revealed plasma cells. Laboratory results indicated the tumor was a solitary plasmacytoma of the rib. He was referred to on- cology and treated with radiation therapy. This case report illustrates an unusual presentation of a solitary plasmacytoma of the rib.
INTRODUCTION Plasma cell tumors are clonal proliferations of cells. There are several types of plasma cell tumors defined by location and manifestation. Multiple myeloma is the most common type of plasma cell tumor and is marked by mul- tiple bony lesions. Solitary plasmacytomas are remarkable for only a localized mass. 1 There are two types of solitary plasmacytomas: extramedullary plasmacytomas, which occur in the soft tissue and solitary plasmacytoma of bone (SPB). Data from population-based cancer registries in the United States indicate multiple myeloma occurs 16 times more frequently than solitary plasmacytomas. 2 In general, plasma cell tumors occurred more frequently in men than women (Incidence Rate Ratio [IRR] of 2.14), and in blacks compared to whites (IRR of 1.30, 95% CI 1.10-1.53). 2 Inci- dence rates of plasma cell tumors were nine times higher in individuals more than 60 years old. 2 Of the solitary plas- macytomas, SPB was more common than extramedullary plasmacytoma (IRR of 1.41, 95% CI 1.25-1.59). 2 Solitary plasmacytomas of bone comprise a significant minority (< 5%) of plasma cell tumors. 3 SPBs typically oc- cur in the vertebrate, with presentation in the rib being less common. 4 Inmost cases, SPBs present as osteolytic lesions of the bone on chest X-ray. 5 This article describes an unusual ra- diologic presentation of SPB of the rib in a 33-year-old man. CASE REPORT A 33-year-old Hispanic man with no past medical his- tory presented to the ED with a one-year history of right
posterior lateral chest wall pain. The pain was constant, sharp in nature, and worsened with movement. His vital signs were within normal limits, and the remainder of the physical examwas unremarkable except for minimal tender- ness to palpation over the right posterior lateral chest wall. Chest X-ray showed absence of a right posterior fifth rib (Figure 1). No surgical scars were noted, and the patient denied any history of removal of a rib. CT of the chest was performed and showed an 8.6 cmmass involving the poste- rior aspect of the right fifth rib (Figure 2). CT-guided biopsy showed sheets of well-differentiated plasma cells infiltrating the bone (Figure 3). Serumprotein electrophoresis and bone marrow biopsy were normal. Urine protein electrophoresis demonstrated a random urine protein level of 28 mg/dL and monoclonal band of beta-globulin of 89.4%. Urine im- munofixation revealed free lambda light chains. Analysis with serum immunofixation and serum free light chains were not performed. The patient’s hemoglobin, hematocrit, serum calcium level, serum creatinine level, serum IgA, IgG, and IgM levels were all within normal limits. A plain radiograph skeletal survey showed no other lytic lesions. The patient was diagnosed with a solitary plasma- cytoma of the rib and referred to oncology clinic. At last follow-up, the patient had undergone radiation therapy and was doing well. His serum protein electrophoresis remains negative at two years, and a skeletal survey shows no further skeletal lytic lesions. DISCUSSION We conducted a literature review using the search terms “solitary plasmacytoma” and “rib.” Exclusion crite-
J La State Med Soc VOL 166 March/April 2014 63
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