Color Atlas of Hematology - Practical Microscopic and Clinical ...

82Abnormalities of the White Cell SeriesMonoclonal Gammopathy (Hypergammaglobulinemia),Multiple Myeloma*, Plasma Cell Myeloma, PlasmacytomaPlasmacytoma is the result of malignant transformation of the mostmature B-lymphocytes (Fig. 1, p. 2). For this reason the diagnostics of thisdisease will be discussed here, even though migration of its specific cellsinto the blood stream (plasma cell leukemia) is extremely rare (1–2%).Immunoelectrophoresis of serum and urine is performed when electrophoresisshows very discrete gammaglobulin, or globulin, fractions, orwhen hypogammaglobulinemia is found (in light-chain plasmacytoma). Awide range of possibilities arises for the differential diagnosis of monoclonaltransformed cells (Table 10).The presence of more than 10% of plasma cells, or atypical plasma cellsin the bone marrow, is an important diagnostic factor in the diagnosis ofplasmacytoma. For more criteria, see p. 84.Table 10Differential diagnosis of monoclonal hypergammaglobulinemiaTypeBenign disorders➤ Essential hypergammaglobulinemia= MGUS (monoclonal gammopathyof unknown significance)➤ Symptomatic hypergammaglobulinemia,secondary to– Infections– Tumors– Autoimmune diseaseMalignant diseases➤ Plasmocytoma(usually IgG, A or light-chain[Bence Jones protein], rarely IgM,D, E) 90% disseminated (multiplemyeloma), 5% solitary, 5%extramedullary (like a lymphomaor ENT tumor)➤ Lymphomae. g., immunocytoma, CLL(potentially all lymphomas of theB-cell series)CharacteristicsUsually in advanced age 10%, plasma cells found in thebone marrow, no progression,normal polyclonal IgAll ages (otherwise as above)– Osteolysis or X-ray with severeosteoporosis– Plasmocytosis of the bone marrow 10%– Monoclonal gammaglobulin inserum/urine with progression– Enlarged lymph nodes– Usually blood lymphocytosis– Monoclonal immunoglobulin,usually IgM* The current WHO classification suggests “multiple myeloma” (MM) for generalizedplasmacytoma and “plasmacytoma” only for the rare solitary or nonosseous form ofplasmacytoma.