Equine gastrointestinale stromale Tumore (GIST) des Dünndarms als Ursache für akute Kolik
Equine gastrointestinal stromal tumours (GISTs) of the small intestine as cause of acute colic
Müller A-C, Onkels A-K, Köhler K, Röcken M
DOI: 10.21836/PEM20210503
Jahr: 2021
Volume: 37
Ausgabe: 5
Seiten: 474–480
Intestinal non-lymphatic neoplasia, which include GIST and GIST-like tumours, are generally rare in horses. GISTs originate from the interstitial cells of Cajal (ICC), which are considered to be enteric pacemaker cells and mediators of neurotransmission. Therefore, they are important regulators of GI motility. Equine GISTs occur predominantly in adult horses from 13 to over 20 years of age, and do not follow breed or sex predisposition. The small intestine is the segment most frequently affected by gastrointestinal tumours. The detection of intestinal tumours merely on the basis of clinical findings is difficult, and they often only can be identified post mortem during necropsy, or intra vitam in the course of a laparotomy or laparoscopy. In advanced stages, such tumours can lead to a decompensated condition requiring euthanasia. The present first case represents a positive outcome after removal of a GIST, which could be identified during laparotomy as cause of colic in a 22-year-old German riding pony mare. In its history, the horse had no problems with colic. Except for pars pituitary intermedia dysfunction (PPID), which was treated with pergolide, the horse showed no other diseases or profoundly abnormal blood parameters. On the basis of rectal and ultrasonographic examinations, the suspicion of small intestinal ileus was raised, and the mare was referred to laparotomy. During exploration of the abdominal cavity, a small intestinal ileus could be confirmed. The cause of strangulation of an approximately 40 cm segment of the jejunum was an intramural proliferation located on the intestinal wall of the mid jejunum around which a part of the small bowel was wrapped. The tumour measured approximately 15 × 15 × 10 cm, was dense to elastic, had a spherical to heart-shaped form with a knobby, smooth and shiny surface and was dark red, partly greyish and multifocal black in colour. On the cut surface, the structure had several blood-filled cavities. The mass was removed together with the corresponding intestinal section including the tumour bed. Rehabilitation of the mare took a good course overall, as she could be discharged from the clinic nine days after surgery. Two years after resection of the tumour, the patient was in a perfect state of health, which allowed normal equestrian use. Pathohistologically, in HE-staining the tumour resembled a classic GIST. The tumour cells had infiltrated all layers of the intestine. In an immunohistochemical examination, the neoplastic cells stained positive for vimentin, S-100, and discovered on GIST Protein 1 (DOG1). Tests for c-kit, desmin, glial fibrillary acid protein (GFAP), akin and smooth muscle antibodies (SMA) were negative. As a result, the proliferation was diagnosed as a myxoid, neurogenic GIST. The second case is a finding as a result of a necropsy of a pony gelding that had to be euthanised due to severe peracute colic. Pre-euthanaisa, using a clinical ultrasonography of the abdomen, a dense image of heterogeneous echogenic structure was detected. Necropsy revealed a tumour with its origin on the intestinal wall, strangulating a section of the jejunum. Similar to the tumour described in the case above, this tumour was about 18 × 15 × 5 cm in total, spherical to heart-shaped, of dense structure with a smooth and shiny surface and dark red and partly greyish-beige and multifocal black in colour. Analogous to the aforementioned case, HE-staining showed classical signs for a GIST, and tumour cells had infiltrated all layers of the intestine. Immunohistochemically, tumour cells were positive for vimentin and c-kit. No signal could be detected for S-100, GFAP, SMA and periaxin. Therefore, this tumour was diagnosed as an undifferentiated GIST. GISTs grow locally invasively and may have multiple occurrences, although metastasis is rarely observed. For a final intra vitam diagnosis, further examinations such as laparoscopy or laparotomy with tissue sampling and pathohistological as well as immunohistochemical examination are recommended, because clinical symptoms are often non specific and do not allow for a clear diagnosis. An early diagnosis with total excision of the tumour is crucial for a successful therapy and a good prognosis.