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]

Differentiating Plasma Cell Neoplasms from Other Diseases

Plasmacytoma

The differential diagnosis of a plasmacytoma includes:

• Plasma cell granuloma

• The plasma cell granuloma shows a balanced proliferation of kappa- and lambda-reacting cells on immunocytochemical evaluation.

• Plasmacytoid lymphoma

• The plasmacytoid lymphoma comprises a mixture of lymphocytes and plasma cells.

• Large cell lymphoma of immunoblastic type

• Immunoblastic lymphoma will usually involve lymph nodes in contrast to plasmacytoma.
• Immunophenotypic studies: immunoblastic lymphomas have cytoplasmic IgM heavy chain and express pan-B-cell surface antigens such as CD19 and CD20. Plasmacytomas contain IgA or IgG heavy chain and are generally negative for pan-B-surface antigens; approximately 20% of plasmacytomas and myelomas are positive with pan-B-cell antibodies.

• For a patient presenting with M protein, the major differential dignosis is among

1. Myeloma
2. MGUS
3. Smoldering myeloma
4. Macroglobulinemia
5. Primary amyloidosis

• In patients suffering from Marrow Plasmacytosis, flow cytometry and immunostaining must be used to differentiate between

1. Monoclonal plasma cell disorders
2. Polyclonal reactive plasmacytosis found in
   1. Autoimmune diseases
   2. Metastatic carcinoma
   3. Chronic liver disease
   4. AIDS
   5. Chronic infection

• Bone leisions must be biposied to diffentiated between

1. Metastatic cancer to bone
2. Multiple myeloma