From: Susan Prock
Date: 2001-07-05 08:53:00 UTC
Subject: Malignant Extramedullary Plasmacytoma
This is Susan Prock of Needham, MA, formerly Susan Wenzel of Sioux Falls,
SD. Here is my vet's report on Jack. I would appreciate any thoughts or
suggestions anyone may have.
Case History: Jack Prock
July 4, 2001
Signalment and Husbandry
This 2-year-old male castrate ferret has been living in the same household
and housed with its littermate since the two were acquired at the age of 6
months from a store in the Midwest USA. The household also includes two
other ferrets. This ferret and its littermate are housed in a large ferret
condo cage that includes ramps, tubes, and hammocks. The ferrets are
allowed out with supervision for 1.5 hours daily. This ferret eats Marshall
Farms ferret kibble and Diamond Maintenance, recently supplemented with
Nutrical and turkey baby food.
Clinical History - This ferret was very robust until approximately 7 months
ago when he developed green, mucoid diarrhea. He had vomited once several
days prior to presentation on 2/3/01 but was bright and alert and was still
eating and drinking. Physical exam findings were normal. Fecal tests for
parasites were negative, and radiographs showed a gas pattern involving the
stomach and intestines. The differential diagnosis included inflammatory
bowel disease (IBD) and gastrointestinal foreign body. The ferret was
treated with oral amoxicillin, which was subsequently supplemented with
metronidazole. Repeat radiographs 3 days later were normal.
· The ferrets stools improved after this dual antibiotic treatment.
Several examinations over the next 3 months revealed no abnormalities, but
the ferret continued to slowly lose weight. The differential diagnosis
included IBD, lymphoma, gastroenteritis, and proliferative bowel disease.
Treatment with chloramphenicol did not result in further clinical
· Results of a complete blood count (CBC) revealed a normal white blood cell
(WBC) count but a relative increase in the number of lymphocytes. The serum
chemistry analysis revealed a markedly elevated total protein
(hyperproteinemia) with an absolute increase in globulins and decrease in
· Considering the findings of absolute hyperglobulinemia and relative
lymphocytosis, the differential diagnosis included neoplasia (multiple
myeloma, lymphoma), lymphocytic gastroenteritis, and Aleutian disease virus
(ADV). The recommendation was to perform an abdominal exploratory and
biopsy the stomach, intestine, liver, and other organs if they appeared
· An abdominal exploratory was performed (5/15/01). The mesenteric lymph
nodes were enlarged, and the bowel was hyperemic (reddened). Biopsies were
submitted from the jejunum (small intestines), mesenteric lymph nodes,
stomach, pancreas, liver, and spleen.
· Biopsy results included disseminated systemic plasmacytosis (small
intestine, spleen, and mesenteric lymph node), moderate multifocal
lymphofollicular hyperplasia (spleen and mesenteric lymph node), and minimal
multifocal lymphocytic portal hepatitis (liver). No abnormalities were seen
in the stomach and pancreas. The pathologist could not determine whether
the systemic plasmacytosis was part of a neoplastic process or an unusual
immunologic response to an unidentified antigen. The plasma cells were not
abnormal in character as they generally are with extramedullary
plasmacytomas in dogs.
· The recommendation was to perform a plasma protein electrophoresis and
test for ADV antibody.
· Both blood and saliva (ELISA test) were negative for ADV antibodies. The
plasma protein electrophoresis revealed a monoclonal gammopathy.
· The primary differential diagnosis was multiple myeloma, and the owner was
interested in any possible treatment.
Further case work-up
· The ferrets weight has increased to the original weight of 1110g. of 2/01
when examined on 6/12/01. Whole body radiographs revealed no abnormalities,
including no bony lesions. A CBC, serum chemistry, and plasma protein
electrophoresis revealed a normal WBC count but a relative lymphocytosis,
hyperproteinemia, and a monoclonal gammopathy all improved from previous
tests described above.
· Several oncology specialists were consulted regarding further diagnostics
tests required to reach a definitive diagnosis in this case. Multiple
myeloma includes lytic bone lesions, a monoclonal gammopathy, and
polysystemic plasmacytosis (also involving the bone marrow) with atypical
plasma cells. In many cases involving dogs, Bence Jones proteins are found
in the urine, but the presence of these proteins in ferret urine is not
certain. The recommendation was to perform a bone marrow aspirate on the
ferret and to collect urine for analysis for Bence Jones urine.
· We were unable to collect sufficient urine for analysis. The bone marrow
aspirate revealed mild plasmacytosis with a mild degree of abnormal
individual cellular morphology. In the absence of lytic bone lesions, the
diagnosis was well-differentiated malignant extramedullary plasmacytoma.
· Although multiple myeloma has been reported in a ferret with a lesion
involving the vertebral column (Methiyapun S, Myers RK, Pohlenz JFL:
Spontaneous plasma cell myeloma in a ferret (Mustela putorius furo). Vet
Pathol 1985; 22: 517-519), we have found no reports of malignant
extramedullary plasmacytoma in the ferret.
· The recommendation from oncology specialists is to treat the ferret with a
combination of melphalan and prednisone. During the treatment period,
periodic CBCs will be monitored to detect bone marrow suppression. Protein
electrophoreses and analyses of bone marrow aspirates will be followed to
monitor response to treatment.
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