Page 1908 - Cote clinical veterinary advisor dogs and cats 4th

Synovial Cell Sarcoma 955.e3

PEARLS & CONSIDERATIONS Technician Tips Feldman EC, et al: Water metabolism and diabetes
The fluid rate during therapy should be moni- insipidus. In Feldman EC, et al, editors: Canine
and feline endocrinology and reproduction, ed 3,
Comments
VetBooks.ir • ADH release may be stimulated by various chronic hyponatremia can result in osmotic Fleeman LM, et al: Effects of an oral vasopressin Diseases and Disorders
tored carefully because too rapid correction of
St. Louis, 2004, Saunders, pp 41-42.
drugs used during anesthesia (barbiturates,
demyelination syndrome.
receptor antagonist (OPC-31260) in a dog with
narcotics) and can result in impaired free
water excretion and hyponatremia in the SUGGESTED READING syndrome of inappropriate secretion of antidiuretic
hormone. Aust Vet J 78:825-830, 2000.
postoperative period, similar to what is seen Meij BP, et al: Hypothalamus-pituitary system. In Van Vonderen IK, et al: Vasopressin response to
in animals with SIADH. Restriction of water Rijnberk A, et al, editors: Clinical endocrinology osmotic stimulation in 18 young dogs with polyuria
intake generally is sufficient to restore normal of dogs and cats, ed 2, Hannover, Germany, 2010, and polydipsia. J Vet Intern Med 18:800-806, 2004.
water balance in these animals. Schlütersche, pp 13-54. AUTHOR: Hans S. Kooistra, DVM, PhD, DECVIM
• Hyperresponsiveness of ADH to osmotic EDITOR: Ellen N. Behrend, VMD, PhD, DACVIM
stimulation has been reported in dogs with ADDITIONAL SUGGESTED
primary polydipsia. READINGS
• In the presence of osmotic stimulation, high DeMonaco SM, et al: Syndrome of inappropriate
plasma ADH concentrations may reflect the antidiuretic hormone secretion in a cat with a
strong, normal pulsatile nature of ADH putative Rathke’s cleft cyst. J Feline Med Surg
release, not SIADH. 16:1010-1015, 2014.

Synovial Cell Sarcoma Client Education
Sheet

BASIC INFORMATION • Subcutaneous mass over the affected joint ○ Abnormalities include soft-tissue swelling
• Joint instability (ligament tear, subluxation) and, in advanced cases, cortical destruction
Definition is possible with longstanding disease. and periosteal reaction.
A malignant tumor in the tissue lining the ○ Radiographic evidence of lysis involv-
capsule of a joint Etiology and Pathophysiology ing the proximal and distal bones of
• Locally invasive tumor with underlying bone a joint is suggestive of SCS; however,
Synonyms destruction is common. other soft-tissue sarcomas can cross
SCS, synovial sarcoma • Metastasis to regional lymph nodes, lungs, the joint space and should be ruled
and other sites: up to 25% of cases out.
Epidemiology • In dogs, SCS most frequently involves the • Fine-needle aspiration (FNA) and cytologic
SPECIES, AGE, SEX stifle and elbow, although other sites are exam of the mass or the affected joint are
Median age (dogs): 8.5 years; rare in cats. reported. useful in identifying and differentiating other
causes of lameness.
GENETICS, BREED PREDISPOSITION DIAGNOSIS • After a diagnosis of malignancy has been
Golden retrievers and flat-coated retrievers seem confirmed, the minimal database should
to be overrepresented. Diagnostic Overview include a CBC, serum biochemical analysis,
A diagnosis of SCS is suspected based on the urinalysis, three-view thoracic radiographs
Clinical Presentation clinical presentation of chronic, progressive or computerized tomographic scan (CT),
DISEASE FORMS/SUBTYPES lameness if the neoplasm is involving an cytologic or histologic exam of the draining
• Two histopathologic types: epithelioid (syn- appendicular joint, typically in an older dog, lymph node, and abdominal ultrasound to
ovioblastic) and spindle (fibrosarcomatous) and especially if a subcutaneous mass or soft- rule out abdominal visceral metastases.
cell types tissue swelling occurs over the joint.
• Histologic grading is based on degree of Advanced or Confirmatory Testing
nuclear pleomorphism (grade I = minimal; Differential Diagnosis • If necessary, CT or MRI to evaluate local
grade III = marked), percent necrosis of the • Degenerative joint disease; immune-mediated extension
tumor (grade I = minimal; grade III = usually or infectious arthritis • Immunohistochemical staining of biopsied
> 15%), and mitotic index (grade I = few • Periarticular histiocytic sarcomas (similar site tissue is almost always necessary to differenti-
mitotic figures; grade III = numerous mitotic predisposition). The distinction is important ate SCS from other malignancies, especially
figures). because each tumor has a characteristic histiocytic sarcoma, other mesenchymal
biologic behavior and response to therapy. tumors, and epithelial malignancies.
HISTORY, CHIEF COMPLAINT • Other joint tumors reported in dogs ○ Markers useful to rule in or rule out
Most animals present with a slow-growing mass include fibrosarcoma, rhabdomyosarcoma, SCS include CD18 (histiocytic-dendritic
over a joint and concurrent lameness. osteosarcoma, malignant fibrous histio- cell marker), cytokeratin (epithelial cell
cytoma, liposarcoma, hemangiosarcoma, marker), and vimentin (mesenchymal cell
PHYSICAL EXAM FINDINGS myxoma, malignant giant cell tumor of marker).
Most signs are directly related to the site of soft tissue, lymphoma, hemangioma, and ○ Reliability of current immunohisto-
involvement and local invasiveness; nonspecific undifferentiated sarcoma. chemistry stains may be equivocal due
signs (lethargy, anorexia, hemiparesis) also are to marked variation in proportions and
possible. Initial Database differentiation of periarticular cellular
• Lameness that may include stiff gait, reduced • Regional radiographs of the affected joint elements.
range of motion, crepitus, joint swelling, and help rule out other causes of musculoskeletal ○ Positive staining for cytokeratin confers
pain. lameness. a worse prognosis.

www.ExpertConsult.com