Sandbox/00036

Template:Plasma cell neoplasm Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]

Overview

Clinical presentations with immunohistochemical profile from flow cytometry and immunostaining may be utilized to differentiate plasma cell neoplasms from other diseases.

Differentiating Plasma Cell Neoplasms from Other Diseases

• For a patient with marrow plasmacytosis, based upon the kappa (κ) and lambda (λ) expression on immunostaining or flow cytometry, the differential dignoses include:

• Monoclonal plasma cell disorders is suggested by a markedly abnormal κ : λ ratio (>4 : 1 or <1 : 2) since plasma cells express either κ or λ.
• Polyclonal reactive plasmacytosis is suggested by the presence of both κ-staining plasma cells and λ-staining plasma cells, usually in a κ : λ ratio of 2 : 1.

• Autoimmune diseases
• Metastatic carcinoma
• Chronic liver disease
• Acquired immunodeficiency syndrome (AIDS)
• Chronic infection

• For a patient with monoclonal (M) proteins, the differential dignoses include: (click here for detailed criteria)

• Monoclonal gammopathy of undetermined significance (MGUS)
• Smoldering multiple myeloma
• Multiple myeloma
• IgM monoclonal gammopathy of undetermined significance (IgM MGUS)
• Smoldering Waldenström macroglobulinemia
• Waldenström macroglobulinemia
• Systemic AL amyloidosis

• For an osteolytic lesion, multiple myeloma may be distinguished from metastatic carcinoma with an unrelated MGUS by the following findings:

• Multiple myeloma is suggested by the presence of serum and/or urinary M protein with ≥10% clonal bone marrow plasma cells.
• Metastatic carcinoma with an unrelated MGUS is suggested by a small M protein with <10% clonal bone marrow plasma cells.

• For plasmacytoma, the differential diagnoses include:

• Plasma cell granuloma is suggested by a balanced proliferation of κ– and λ–reacting plasma cells on immunohistochemical studies.
• Plasmacytoid lymphoma is suggested by a mixture of lymphocytes and plasma cells.
• Large cell lymphoma of immunoblastic type is suggested by the predominat lymph node involvement with expression of cytoplasmic IgM heavy chain and pan–B-cell surface antigens, whereas plasmacytoma typically has IgA or IgG heavy chain and is negative for pan–B-cell surface antigens.