title: Gastrointestinal stromal tumors and leiomyomas in the dog: a histopathologic, immunohistochemical, and molecular genetic study of 50 cases.
abstract: Fifty canine gastrointestinal (GI) mesenchymal tumors were examined to determine the occurrence of leiomyomas (LM) and GI stromal tumors and to compare their clinicopathologic features. Twenty-one tumors (42%) were histologically reclassified as gastrointestinal stromal tumors (GISTs) and 29 tumors (58%) as LMs on the basis of their histologic similarity with homologous human tumors. The GISTs occurred equally in males and females, with a mean age of 11 years (range 5-14 years). Five GISTs (24%) were associated with clinical signs and six (29%) had metastasis in liver or abdominal cavity. The GISTs occurred in large intestine (10, 48%), small bowel (six, 29%), stomach (four, 19%), and mesentery of small intestine (one, 5%). Histologically, they were highly cellular spindle, or less commonly epithelioid tumors with mitotic rates ranging from 0 to 19 per 10 HPF. Eleven tumors (52%) were positive for CD117 (KIT); seven (33%) were positive for smooth muscle actin but none for desmin and S-100 protein. Sequences of KIT exon 11, often mutated in human GISTs, were evaluated from four GISTs. Deletion of Try556-Lys557 coexisting with duplication of Gln555 in one case of GIST and T to C transition resulting in substitution of Pro for Leu575 in another were identified. The LMs occurred predominantly in males (82%) with a mean age of 11 years (range 8-17 years). Nine tumors (31%) had associated clinical signs. They occurred in the stomach (22, 76%), esophagus (four, 14%), and intestines (three, 10%); all were paucicellular, had no mitoses, and were composed of mature smooth muscle cells. Twenty-eight (97%) were positive for smooth muscle actin and 18 (62%) for desmin but none for CD117 and S-100. Both GISTs and true LMs occur in the GI tract of dogs. Both tumors have distinctive pathologic features.
authors.affiliation: Armed Forces Institute of Pathology, Washington, DC 20306-6000, USA.
authors.forename: D
authors.initials: D
authors.lastname: Frost
authors.forename: J
authors.initials: J
authors.lastname: Lasota
authors.forename: M
authors.initials: M
authors.lastname: Miettinen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D004283:Dog Diseases / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D004285:Dogs; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D007150:Immunohistochemistry / Q000662:veterinary; D007889:Leiomyoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction / Q000662:veterinary; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017154:Stromal Cells / Q000473:pathology
chemical_list: D004273:DNA, Neoplasm; D019009:Proto-Oncogene Proteins c-kit