Myeloma : Pathologic Fracture

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Image Description

One of the diagnostic hallmarks of plasma cell myeloma is lytic bone lesions. These lytic lesions are mediated by a complex interplay between factors secreted by neoplastic plasma cells. One such mediator is MIP1 alpha which, after a series of complex interactions, upregulates osteoclastic activity. At the same time, the tumor cells also synthesize modulators of the Wnt pathway that are suppressors of osteoblastic activity. The end result is increased bone resorption which increases the risk of pathologic fractures and also causes hypercalcemia.

This plain radiograph is from 65 y/o male with a known history of plasma cell myeloma who presented with right hip pain. Patient reported hearing a crack before the onset of pain. The radiograph shows right subtrochanteric pathologic fracture. The fracture is posteriorly displaced and mildly impacted. The proximal fracture fragment is laterally angulated. Surrounding the fracture is a lytic lesion, which had been previously demonstrated as a myelomatous deposit. Pathological fracture refers to a fracture through an area of underlying abnormal bone. Although in the vast majority of cases there is an underlying malignant lesion, such as a metastasis or myelomatous deposit, this need not always be the case. Pathological fractures are a common complication of plasma cell myeloma. Case courtesy of Dr Henry Knipe, Radiopaedia.org. From the case rID: 25272

About the Disease

Plasma cell disorders are B-cell neoplasms composed of plasma cells or lymphocytes that secrete a monoclonal immunoglobulin (Ig) or Ig fragment. They are responsible for about 15% of deaths caused by lymphoid malignancies in the US. The monoclonal Ig, usually identified by serum or urine protein electrophoresis, is known as the M component. Sometimes the M component consists of only light chains or heavy chains. Free light chains are referred to as Bence-Jones proteins when they are excreted in urine. The WHO Classification (2008) of plasma cell neoplasms includes the following: Monoclonal Gammopathy of Undetermined Significance (MGUS): MGUS refers to an asymptomatic patient with an M component (<3 gm/dl) in their blood. It is the most common plasma cell disorder and is seen in about 5% of individuals >70 years of age. About 1% of MGUS patients per year develop multiple myeloma, amyloidosis, macroglobulinemia, or other lymphoproliferative disorder. The median interval between the diagnosis of MGUS and the development of malignancy is about 10.5 years. Plasma Cell Myeloma: Multiple myeloma (MM) is a plasma cell neoplasm of older individuals that is characterized by scattered tumorous masses causing lytic bone lesions in the axial skeleton, hypercalcemia, renal damage, and acquired immune abnormalities. Solitary Plasmacytoma: About 3% to 5% of patients with plasma cell disorders present with solitary bone or soft tissue mass. An M component may be found in serum or urine in a small percentage of cases. Solitary bone plasmacytoma slowly progresses to multiple myeloma in most cases. Extraosseous plasmacytomas involve lungs, nasopharynx, oropharynx, or nasal sinuses and can often be cured by resection. Immunoglobulin Deposition Diseases: This group includes primary amyloidosis (PA) and light- or heavy- chain deposition disease. Immunoglobulins are deposited in various tissues eventually leading to organ failure. About 20% of PA patients have multiple myeloma (MM). The remainder don't meet the criteria for MM but have a small M component and increased plasma cells in bone marrow. Osteosclerotic Myeloma (POEMS Syndrome): Osteosclerotic myeloma is usually associated with polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin lesions (POEMS syndrome). Some patients also develop Castleman's disease, serous effusions, and thrombocytosis.

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