Reclassification of small intestinal and cecal smooth muscle tumors in 72 dogs: clinical, histologic, and immunohistochemical evaluation.
OBJECTIVE
To reclassify canine small intestinal and cecal leiomyoma (LM) and leiomyosarcoma (LMS) into smooth muscle and gastrointestinal stromal tumors (GIST) using histologic and immunohistochemical (IH) analysis and to report clinical findings and survival data.


METHODS
Retrospective review of cases.


METHODS
Dogs (n=47) with small intestinal (40 LMS; 7 LM) and 25 dogs with cecal tumors (23 LMS; 2 LM).


METHODS
Clinical and survival data were reviewed. Tissue sections were reevaluated for light-microscopic malignancy criteria and examined for expression of SMA, desmin, vimentin, S-100, and CD117 (KIT) by immunohistochemistry.


RESULTS
Reclassification resulted in 2 LM, 9 LMS, 19 GIST, and 17 GIST-like tumors in the small intestine and 23 GIST and 2 GIST-like tumors in the cecum. GIST-like tumors were morphologic and IH identical to GIST but lacked KIT expression. No significant difference in survival was observed for tumor type, location, histologic, or IH characteristics; however, dogs with cecal tumors were significantly older in age, presented more commonly with intestinal perforation and peritonitis, and less commonly with weight loss. Cecal tumors had more histologic malignancy criteria than small intestinal tumors. After excision, 1 and 2 year recurrence-free periods were 80.1% and 67.2% for small intestinal and 83.3% and 61.9% for cecal tumors.


CONCLUSIONS
Prognosis for intestinal tumors with histologic smooth muscle appearance is good after excision and not related to tumor type, location, histologic, or IH characteristics.


CONCLUSIONS
Clinical importance could not be demonstrated for reclassification, but may be for future treatment, of intestinal smooth muscle or stromal tumors.
Maas
Ceriel P H J
CP
Department of Clinical Sciences of Companion Animals, University of Utrecht, Utrecht, The Netherlands.
ter Haar
Gert
G
van der Gaag
Ingrid
I
Kirpensteijn
Jolle
J
D000818:Animals; D002432:Cecum / Q000473:pathology; D003937:Diagnosis, Differential; D004283:Dog Diseases / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery; D004285:Dogs; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000175:diagnosis / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D007150:Immunohistochemistry / Q000662:veterinary; D007421:Intestine, Small / Q000473:pathology; D007889:Leiomyoma / Q000175:diagnosis / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D007890:Leiomyosarcoma / Q000145:classification / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D008297:Male; D019042:Muscle Neoplasms / Q000175:diagnosis / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D009364:Neoplasm Recurrence, Local / Q000662:veterinary; D011379:Prognosis; D012189:Retrospective Studies; D016896:Treatment Outcome