Multiple myeloma (MM): Clinical picture, laboratory manifestations, and diagnosis

Clinical presentation: MM is typically characterizing by the neoplastic proliferation of Ig-producing plasma cells.

Multiple myeloma (MM): Clinical picture, laboratory manifestations, and diagnosis

 

Clinical presentation: MM is typically characterizing by the neoplastic proliferation of Ig-producing plasma cells. Most ptns present with Sns or Sms related to the infiltration of plasma cells into > the bone or systemic organs or to renal damage from excess light chain. Common presentation includes anemia, bony pains, increased Cr or S. protein, fatigue, & hypercalcemia. Less common features requiring urgent assessment may include spinal cord compression, acute renal failure, intense hypercalcemia & hyperviscosity.

 

Evaluation of suspected cases: Ptns with suspected MM or similar disorders, initial screening testing may include SPE (serum protein electrophoresis) along with immunofixation, and a serum free light chain (FLC) assay. Further assessment to confirm the Dgx of MM may include a bone marrow aspiration and biopsy, radiological examination, CBC + differential & full biochemistry screening. A 24-h urine collection for electrophoresis & immunofixation is crucial to evaluate the monoclonal protein & total urine protein content. Magnitude of infiltration of the bone marrow with malignant plasma cells is variable, it may be focal, needs aspiration/biopsy at variable locations. MRI and/or positron emission tomography (PET) may help locating the suspected foci.  

 

Diagnostic criteria: The diagnosis of MM requires: ≥10 % clonal plasma cells in bone marrow or biopsy-proven bony or soft tissue plasmacytoma + one of the following:

• Organ dysfunction that can be attributed to the plasma cell proliferative disorder (e.g., higher Ca⁺, kidney dysfunction, anemia, lytic bone lesion)
• Biomarker with near inevitable progression to end-organ damage (i.e., ≥60 % clonal plasma cells in bone marrow; involved/uninvolved FLC ratio of 100 or more [involved FLC level must be 100 mg/L or more]; or MRI with > one focal lesion)

 

Differential diagnosis: The main disorders considered in DD for MM include MGUS, smoldering MM, Waldenström macroglobulinemia, solitary plasmacytoma, AL amyloidosis, POEMS syndrome, as well as metastatic carcinoma