Clinical and immunohistochemical differentiation of gastrointestinal stromal tumors from leiomyosarcomas in dogs: 42 cases (1990-2003).
OBJECTIVE
To reexamine (via immunohistochemical techniques) canine tissue samples that had been previously classified as gastrointestinal leiomyosarcomas (GILMSs), identify and differentiate gastrointestinal stromal tumors (GISTs) from GILMSs, and compare the biological behavior and clinical course of GISTs and GILMSs in dogs.


METHODS
Retrospective case series.


METHODS
42 dogs.


METHODS
Medical records of 42 dogs for which a histologic diagnosis of GILMS was confirmed were reviewed for signalment, clinical signs, physical examination findings, results of initial diagnostic tests, surgical findings, adjunctive treatment, location of the tumor, completeness of resection, and outcome after surgery. Archived tumor tissue specimens from each dog were restained via immunohistochemical techniques to differentiate tumor types. Long-term follow-up information was obtained from the medical record or through telephone interviews with owners and referring veterinarians.


RESULTS
On the basis of immunohistochemical findings, 28 of 42 tumors were reclassified as GISTs and 4 were reclassified as undifferentiated sarcomas; 10 tumors were GILMSs. In dogs, GISTs developed more frequently in the cecum and large intestine and GILMSs developed more frequently in the stomach and small intestine. Median survival times for dogs with GISTs and GILMSs were 11.6 and 7.8 months, respectively; if only dogs surviving the perioperative period were considered, median survival times were 37.4 and 7.8 months, respectively. These differences, however, were not significant.


CONCLUSIONS
In dogs, many previously diagnosed GILMSs should be reclassified as GISTs on the basis of results of immunohistochemical staining. The biological behavior of these tumors appears to be different.
Russell
Kelli N
KN
Matthew J. Ryan Veterinary Hospital, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Mehler
Stephen J
SJ
Skorupski
Katherine A
KA
Baez
Jennifer L
JL
Shofer
Frances S
FS
Goldschmidt
Michael H
MH
D000818:Animals; D003937:Diagnosis, Differential; D004283:Dog Diseases / Q000175:diagnosis / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D004285:Dogs; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000175:diagnosis / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D007150:Immunohistochemistry / Q000379:methods / Q000662:veterinary*; D007890:Leiomyosarcoma / Q000175:diagnosis / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D008297:Male; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome