Differentials
Multiple myeloma or smoldering myeloma
SIGNS / SYMPTOMS
Common symptoms: weakness and fatigue, bone pain, recurrent infections, confusion and altered mental status related to metabolic complications, and numbness and tingling related to neuropathy or compressive symptoms. These are vague and nonspecific signs.
INVESTIGATIONS
Serum M-protein (IgG or IgA) ≥30 g/L (≥3 g/dL); urine monoclonal protein ≥500 mg/day; monoclonal plasma cell infiltration in the bone marrow ≥10%
Amyloidosis
SIGNS / SYMPTOMS
Significant degrees of proteinuria, hepatomegaly, or cardiomyopathy.
INVESTIGATIONS
Sural nerve or tissue biopsy is positive with Congo red staining.
Waldenström macroglobulinemia
SIGNS / SYMPTOMS
Symptoms related to hyperviscosity syndrome, hepatomegaly, splenomegaly, lymphadenopathy, anorexia, and fatigue.
INVESTIGATIONS
Possible abnormal CBC.
Serum IgM: >3 g/dL.
Bone marrow biopsy: >10% of lymphoplasmacytic cells.
Chronic lymphocytic leukemia
SIGNS / SYMPTOMS
Lymphadenopathy and splenomegaly. Anemia is less common but a strong diagnostic factor and may cause lethargy and shortness of breath.
INVESTIGATIONS
Elevated WBC count with absolute lymphocytosis >5000/microliter; anemia and thrombocytopenia are less common.
Flow cytometry positive for CD5, CD19, and CD23 confirms diagnosis.
Non-Hodgkin lymphoma
SIGNS / SYMPTOMS
Constitutional symptoms, such as night sweats, fevers, and weight loss, are common. Lymphadenopathy and splenomegaly may also be present.
INVESTIGATIONS
CBC with differential may show thrombocytopenia or pancytopenia.
Bone marrow or lymph node biopsy may be positive for lymphoma.
Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)
SIGNS / SYMPTOMS
Weakness is a prominent feature of CIDP. Features of the underlying cause (e.g., indications of infection or malignancy) may be present.
INVESTIGATIONS
Nerve conduction studies show a combination of slowed conduction velocities, prolonged distal latencies, prolonged F-wave latencies, and conduction block in ≥1 nerves.
Nerve biopsies demonstrate increased numbers of macrophages.
Unusually high cerebrospinal fluid protein.
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