Page 767 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 33 Hematopoietic Tumors 745

TABLE 33.16 Approximate Frequency of Clinical Diagnostic Abnormalities for Dogs and Cats with Multiple
Myeloma (n = 68 cats, 134 dogs) 757,761,762,764,767,769–771,788
VetBooks.ir Abnormality Dogs FREQUENCY RANGE REPORTED (%)
Cats
Increased M component 99 94–98
Monoclonal 95 77–100
Biclonal 5% a 16–23
IgG 40 84
IgA 60 16
Noncutaneous extramedullary extension NR 65–100 b
Marrow plasmacytosis (>10%) 100 50–100
Complete blood count (CBC) abnormalities
Anemia (nonregenerative) 61 50–80
Thrombocytopenia 39 50
Neutropenia 26 37
Circulating plasma cells (leukemia) 7 5–25
Hypoalbuminemia 62 36–60
Hypocholesterolemia NR 68
Proteinuria 45 71–91
Bence Jones proteinuria 38 40–59
Bone lysis 64 5–45
Serum hyperviscosity 35 35–44
Azotemia 29 22–40
Hypercalcemia 27 10–25
Increased activities of liver enzymes NR 43–50

a Several single case reports exist for biclonal gammopathy in dogs with MM.
b 11 of 11 in one report had evidence of infiltration in either spleen, lymph node, or liver.
NR, Not reported.

or where EMP is suspected in the absence of marrow involvement MM because this modality reveals involvement of one or more
and will be discussed in subsequent sections; however, they have abdominal organs in the majority of cases. These include spleno-
been occasionally useful in the diagnosis of MM. Molecular diag- megaly with or without nodules, diffuse hyperechoic hepatomeg-
nostic techniques for MM have received limited use thus far in aly with or without nodules, renomegaly, and iliac lymph node
veterinary oncology; however, determining clonality of the immu- enlargement. In one case series in cats with MM, 85% of organs
noglobulin heavy chain variable region gene has been performed with ultrasonographic abnormalities were subsequently confirmed
in feline and canine plasmacytoma and myeloma using PARR to have plasma cell infiltration. 771 Skeletal survey radiographs are
techniques (see Chapter 8), 762,834 and use of this technology in recommended to determine presence and extent of osteolytic
cases where diagnosis is not straightforward is expanding. The lesions, which may have diagnostic, prognostic, and therapeutic
author has used PARR analysis both before treatment and after implications. Although nuclear scintigraphy (bone scan) for clini-
clinical remission in a small number of dogs with MM involved cal staging of dogs with MM has been performed, because of the
in clinical trials and documented its utility for (1) initial diagnosis predominant osteolytic activity with osteoblastic inactivity pres-
and (2) to characterize molecular remission. 762 ent, scans seldom give positive results and are therefore not useful
for routine diagnosis. 835 In physician-based oncology, bone min-
Imaging eral density analysis (dual-energy x-ray absorptiometry [DEXA]
Routine thoracic and abdominal radiographs are recommended scan) to document osteoporosis, MRI of bone marrow, and PET/
in suspected cases. Occasionally, bony lesions can be observed in CT are commonly used for staging; however, these modalities have
skeletal areas on these standard films, and organomegaly (liver, not been applied consistently in the veterinary literature. A clini-
spleen, kidney) is observed in the majority of cats. 767,769,771 cal staging system for canine MM has been suggested 757 ; however,
Abdominal ultrasound is recommended in all cats suspected of at present, no prognostic significance has been attributed to it.