Malignant olecranon bursitis in the setting of multiple myeloma relapse

Discussion

Our patient experienced left olecranon bursitis simultaneously with relapse of multiple myeloma and AL amyloidosis. Evaluation for infectious causes was negative, and the bursal fluid did not have strongly inflammatory characteristics. Furthermore, a small plasma cell population was isolated from the fluid. Imaging did not reveal an underlying dominant lytic lesion. Although we do not have direct pathologic confirmation, the clinical scenario and flow cytometry findings support our interpretation that the patient’s bursitis was caused by or at least related to underlying multiple myeloma. While reactive plasma cells are also CD38 positive and CD138 positive, they maintain the expression of CD19 and CD45 without aberrant expression of CD56 or CD117 and do not show loss of expression of CD81 or CD27. In this situation, we suspect that either a plasmacytoma involving the soft tissue of the bursa or amyloid infiltration of the synovium may have occurred. Anti-myeloma therapies and radiation therapy did not result in control of the bursitis, though it should be noted that the patient’s highly refractory disease progressed despite treatment with a combination of later-generation immunomodulatory imide and proteasome inhibitor therapies.

Cases of malignant bursitis have been reported several times in the literature, though nearly all of the instances involved connective tissue or metastatic tumors. Tumor histologies include osteochondroma,^8,9 malignant fibrous histiocytoma,¹⁰ synovial sarcoma,¹¹ and metastatic breast cancer.¹²

Hematologic malignancies are more rare causes of bursitis; our literature search identified a report of 2 cases of non-Hodgkin lymphoma mimicking rheumatoid arthritis. The joints were the knee and elbow. Synovial fluid from one case was clear and yellow, with leukocytosis with a neutrophilic predominance (similar to our case). In both cases, pathology confirmed lymphomatous infiltration of the synovium.¹³ Notably, we identified a case of a previously healthy 35-year-old woman with bilateral trochanteric bursitis. Biopsy of tissue from the right trochanteric bursa demonstrated positive birefringence, diagnostic of AL amyloidosis. The patient also had a biclonal paraprotein accompanied by calvarial lytic lesions. She was treated with a corticosteroid pulse and bisphosphonates, followed by autologous hematopoietic stem cell transplant. ⁵ Our case shares features with the above case, including the relatively young age of the patient and the presence of AL amyloidosis.

Our patient wished to avoid a surgical biopsy procedure, and therefore we utilized flow cytometry of the bursal fluid to establish that the etiology of fluid collection was consistent with his concurrent relapse of multiple myeloma. We believe that we are reporting the second case of multiple myeloma-associated bursitis and the first case associated with multiple myeloma relapse; to our knowledge, it is the first to be diagnosed with the aid of flow cytometry.

Because of our patient’s reliance on hemodialysis beginning one year prior to his presentation with olecranon bursitis, we entertain “dialysis elbow” within the differential diagnosis. Dialysis elbow is a relatively uncommon complication of dialysis, in which patients develop olecranon bursitis on the same side as the hemodialysis access after a prolonged (months to years) duration of hemodialysis. Serositis and mechanical forces are the hypothesized etiologies¹⁴; infectious and rheumatologic causes were excluded from the reported cases. Nevertheless, we favor a malignant cause based upon the flow cytometry findings indicating involvement by immunophenotypically abnormal plasma cells.

Our patient was treated initially with serial drainage and nonsteroidals, which had little impact. After diagnosis of a plasma cell population in the fluid, we offered local treatment with radiation and systemic treatment of multiple myeloma, which offered better but suboptimal control. Possible treatments for olecranon bursitis include surgery, corticosteroid injections, anti-inflammatories, and serial drainage. Nonsurgical management may be more effective than surgical management, and corticosteroid injection carries significant risks. On the other hand, serial drainage does not confer additional infection risk in cases with aseptic etiology.¹⁵ We combined conservative measures as well as treatment of the underlying disease, but we believe that our patient did not derive significant benefit because of the refractory nature of his disease; he also expressed a preference to avoid surgical intervention.