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

84Abnormalities of the White Cell SeriesVariability of Plasmacytoma MorphologyIt is not easy to visually distinguish malignant cells from normal plasmacells. Like lymphocytes, normal plasma cells have a densely structured nucleus.Plasma cell nuclei with radial chromatin organization, known as“wheel-spoke nuclei,” are mostly seen during histological analysis.The following attributes suggest a malignant character of plasma cells:the cells are unusually large (Fig. 28 c), they contain crystalline inclusionsor protein inclusions (“Russell bodies”) (Fig. 28 b), or they have more thanone nucleus (Fig. 28 c).In the differential diagnosis, they must be distinguished from hematopoieticprecursor cells (Fig. 28 d), osteoblasts (Fig. 20 c), and blasts in acuteleukemias (see Fig. 31, p. 97).Bone marrow involvement may be focal or in rare cases even solitary.Aside from cytological tests, bone marrow histology assays are thereforeindicated. Sometimes, the biopsy must be obtained from a clearly identifiedosteolytic region.Although plasmacytomas progress slowly, staging criteria are available(staging according to Salmon and Durie) (Table 11).Therapy may be put on hold in stage I. Smoldering indolent myelomacan be left for a considerable time without the introduction of therapystress. However, chemotherapy is indicated once the myeloma hasexceeded the stage 1 criteria.Table 11Staging of plasmacytomas according to Salmon and DurieStage IAll the following are present:– Hb 10 g/dl– Serum calcium is normal– X-ray shows normal bone structureor solitary skeletal plasmacytoma– IgG 5 g/dl*IgA 3 g/dl*Light chains in the urine* 4 g/24 h* Monoclonal in each case.Stage IIFindings fulfill neither stage I norstage III criteriaStage IIIOne or more of the following arepresent:– Hb 8.5 g/dl– Serum calcium is elevated– X-ray shows advanced bone lesions– IgG 7 g/dl*IgA 5 g/dl*Light chains in the urine: 12 g/24 h