Page 398 - Textbook of Pathology, 6th Edition

382 cells but usually lacks the cart-wheel chromatin pattern
seen in classical plasma cells. Nucleoli are frequently
present. The cytoplasm of these cells is abundant and
basophilic with perinuclear halo, vacuolisation and
contains Russell bodies consisting of hyaline globules
composed of synthesised immunoglobulin (Fig. 14.26).
In addition to neoplastic proliferation of plasma cells
in multiple myeloma, reactive plasmacytosis in the bone
marrow can occur in some other disorders; these include:
aplastic anaemia, rheumatoid arthritis, SLE, cirrhosis of
liver, metastatic cancer and chronic inflammation and
infections such as tuberculosis. However, in all these
conditions the plasma cells are mature and they do not
exceed 10% of the total marrow cells.
B. EXTRAOSSEOUS LESIONS. Late in the course of
disease, lesions at several extraosseous sites become
evident. Some of the commonly involved sites are as
under:
1. Blood. Approximately 50% of patients with multiple
SECTION II
myeloma have a few atypical plasma cells in the blood.
Other changes in the blood in myeloma are the presence
of anaemia (usually normocytic normochromic type),
marked red cell rouleaux formation due to hypervisco-
sity of blood, and an elevated ESR.
2. Myeloma kidney. Renal involvement in myeloma
called myeloma nephrosis occurs in many cases (Chapter
22). The main mechanism of myeloma kidney is by
Figure 14.25 The major sites of lesions in multiple myeloma. filtration of light chain proteins (Bence Jones proteins)
which are precipitated in the distal convoluted tubules in
combination with Tamm-Horsfall proteins as tubular
i) Cellularity: There is usually hypercellularity of the casts. The casts may be surrounded by some multinucleate
bone marrow. giant-cells and a few inflammatory cells.
ii) Myeloma cells: Myeloma cells constitute >10% of the 3. Myeloma neuropathy. Infiltration of the nerve trunk
marrow cellularity. These cells may form clumps or sheets, roots by tumour cells produces nonspecific polyneuro-
or may be scattered among the normal haematopoietic pathy. Pathologic fractures, particularly of the vertebrae,
cells. Myeloma cells may vary in size from small, may occur causing neurologic complications.
differentiated cells resembling normal plasma cells to 4. Systemic amyloidosis. Systemic primary generalised
large, immature and undifferentiated cells. Binucleate and amyloidosis (AL amyloid) may occur in 10% cases of
multinucleate cells are sometimes present. The nucleus multiple myeloma and involve multiple organs and
of myeloma cell is commonly eccentric similar to plasma systems.

Haematology and Lymphoreticular Tissues

Figure 14.26 Bone marrow aspirate in myeloma showing numerous plasma cells, many with abnormal features.