Felis ISSN 2398-2950

Multiple myeloma

Contributor(s): Michael Day, David Godfrey

Introduction

  • Multiple myeloma is rare in cats. There are no large case series in the literature.
  • They are neoplasms of well differentiated B cells present in the bone marrow. When similar neoplasms are present only in extra-medullary sites they are called plasma cell neoplasms or plasmacytoma Plasmacytoma.
  • They usually cause disease due to the side-effects of the hyperproduction of protein into the circulation but they can also cause bone pain or fractures, hypercalcemia Blood biochemistry: total calcium  and bone marrow dysfunction.

Pathogenesis

Etiology

  • The etiology is unknown.
  • Retroviruses do not seem to be incriminated.

Pathophysiology

  • The clone of neoplastic plasma cells overproduces an immunoglobulin (14/18 cats in which it has been reported produced an IgG, 3/18 IgA and 1/18 IgM). A progressively worsening hyperglobulinemia ensues. This causes hyperviscosity of the blood which can produce cerebral dysfunction, blindness, retinal hemorrhage and heart failure. The globulins also affect the function of platelets and coagulation proteins which can lead to bleeding problems. Associated with the monoglobulinemia are hyposecretion of other globulins and dysfunction of T cells; the reasons are uncertain but affected cats are often immunosuppressed and succumb to local bacterial infections or sepsis.
  • The neoplasm may overproduce the light chain of the immunoglobulin compared to the heavy chain. These light chains are small enough to pass through the renal glomerulus into the urine where they can be detected as Bence Jones proteins.
  • The expanding neoplasm will eventually damage the bone enough to cause pain or fracture. This bone damage may also cause a hypercalcemia. Some tumors will cause local bone disease before they cause hyperglobulinemia.
  • Neoplastic cells in the marrow will eventually disrupt normal marrow function and cause a non-regenerative anemia.
  • If the neoplasm is producing cryoglobins these precipitate on cooling and will block blood vessels in the colder parts of the skin ie ear tips, nose, tail tip and toes.

Timecourse

  • Progression seems to be relatively rapid. In the literature many untreated cats were euthanased after only a few weeks due to worsening disease.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Hanna F (2005) Multiple myelomas in cats. J Feline Med & Surg (5), 275-287 PubMed.
  • Hickford F H, Stokol T, vanGessel Y A et al (2000) Monoclonal immunoglobulin G cryoglobulinemia and multiple myeloma in a domestic shorthair cat. JAVMA 217 (7), 1029-1033 PubMed.
  • Weber N A & Tebeau C S (1998) An unusual presentation of multiple myeloma in two cats. JAAHA 34 (6), 477-83 PubMed.


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