Gastrointestinal stromal tumors (GISTs) are rare tumors accounting for 0.1-3% of gastrointestinal (GI) neoplasms. ‏In the past, GIST was classified as leiomyomas, leiomyosarcomas, and leiomyoblastomas. However, now it is evident that GIST is a separate tumor entity, and it is the most frequent sarcoma of the GI tract. We report a case of a 57-year-old female with a five-day history of black tarry stools, two episodes of vomiting of dark-colored blood, dizziness, abdominal pain, night sweats, and palpitation, provoked by a change of position. After a computerized tomography (CT) of the abdomen and pelvis, a GIST was suspected, which was confirmed with histopathology. Acute upper GI bleeding is a rare presentation of GIST. Clear guidelines should be developed for GIST. An early diagnosis is crucial for a better prognosis.

A gastrointestinal stromal tumor (GIST) is a rare malignancy, accounting for only 0.1% to 3% of all gastrointestinal (GI) malignancies. Although GISTs are the most common mesenchymal tumor of the GI tract, they are primarily found within the stomach, with rectal GISTs rarely reported. They may present with rectal bleeding, constipation, pain, or a palpable mass while some are found incidentally. The incidence of GISTs has been on the rise, possibly due to advancements in diagnostic technology. In this case report, we present a 50-year-old female who presented with intermittent constipation and rectal pain and was found to have a submucosal rectal mass during a routine diagnostic colonoscopy. Further evaluation confirmed the presence of a spindle-cell neoplasm, which was mildly cellular and showed positive expression of CD34 and CD117 on immunohistochemistry, consistent with the diagnosis of GIST of the rectum. This case report emphasizes the importance of routine colonoscopies in the early detection of neoplastic lesions of the colon and highlights the rare incidence of GISTs, their risk factors, pathogenesis, and common sites of occurrence.

Gastrointestinal stromal tumors are rare, and in pregnancy they are extremely rare. We present a case of a maternal gastrointestinal stromal tumor found in the second trimester of pregnancy. A 29-year-old woman, gravida 1 para 0, complained of bloody vomiting at 14 weeks of gestation. She had no significant medical history. We performed plain computed tomography and upper gastrointestinal endoscopy. Precise examination revealed a large mass in the stomach and an exposed blood vessel on the surface. An exposed blood vessel can be harmful for mother and fetus as it might rupture during the pregnancy. We performed a distal gastrectomy at 16 weeks of gestation. Histology confirmed a localized gastrointestinal stromal tumor with a high risk of recurrence, and adjuvant imatinib was recommended. The patient elected to delay adjuvant imatinib until after delivery. The postoperative and antenatal course was favorable, and the patient was followed up by ultrasound every 2 months after the operation. After she gave birth at 40 weeks of gestation, she started adjuvant imatinib 400 mg/day. There was no evidence of recurrence 1 year after surgery. There are no guidelines for the management of gastrointestinal stromal tumors in pregnancy. Given the treatment challenges, we believe that pregnant patients should be managed by a multidisciplinary team with expertise in gastrointestinal tumors and fetal-maternal medicine.

OBJECTIVE: In this study, we reviewed GISTs with all morphological and immunohistochemical findings and assessed the prognostic parameters of these tumors.
METHODS: Files of 40 cases with GIST operated between 2002 and 2008 were retrospectively examined in this study. Patients were grouped as patients with and without recurrence within postop 1 year. The patients were grouped based on their localization, gender and age. The cases were stratified as the risk grades based on risk categorization table developed by Fletcher et al. according to the tumor diameter and number of mitoses. The cases were immunohistochemically investigated for CD117, CD34, S100, and Ki-67.
RESULTS: Male/female ratio was 25/15. The mean age was 61.55. Mean tumor diameters were statistically significantly higher in the recurrence (+) group than in the recurrence (-) group (p=0.048). The mean number of mitoses was statistically significantly higher in the recurrence (+) group than in the recurrence (-) group (p=0.038). No statistically significant difference was found in histological distribution of the recurrence (-) and recurrence (+) groups (p=0.8795). No statistically significant difference was found in CD34, S100, and Ki-67 distribution of the recurrence (-) and recurrence (+) groups (p=0.862, p=0.609, and p=0.023, respectively). All patients in the recurrence (+) group were in the high-risk group.
CONCLUSIONS: GISTs are studied in a wide range from benign, incidental tumors to malignant tumors with the risk for recurrence and metastasis concerning biological behaviour. GISTs have prognostic parameters, such as tumor localization, tumor diameter, mitotic index, cellularity, and pleomorphism grade.

We report a case of an extremely rare type of duodenal gastrointestinal stromal tumor (GIST) that included neuronal components. Although gastrointestinal autonomic nerve tumors (GANTs), a subtype of GISTs, exhibit ultrastructural features of the nerve plexus, neuronal cells have not been observed within GANTs or GISTs. GISTs originate from interstitial cells of Cajal (ICCs), which are markedly different from the progenitor cells of neural elements and neural-crest-derived stem cells. This may explain why GISTs typically lack neuronal elements. It remains unclear that the neuronal components of this tumor are neoplastic or hyperplastic, but proliferation and survival of ICCs have recently been reported to be closely related to neurons. Although we could not find the KIT, PDGFR, and BRAF mutation as far as we examined, it may have had a rare mutation in NF1, a fusion of EVT6-NTRK3, or an as-yet-unknown KIT mutation that affected neurogenesis. Further investigation of related genetic mutations and accumulation of data from other similar cases is needed.

Multiple gastrointestinal stromal tumors (GISTs) caused by germline KIT gene mutations are an extremely rare autosomal dominant disorder. We report a case of a 21-year-old woman who presented to the emergency department with a 2-week history of asthenia, palpitations and upper gastrointestinal bleeding. After further clinical evaluation one gastric and two small bowel GISTs were diagnosed, which were surgically resected after neoadjuvant therapy with Imatinib. Diffuse hyperplasia of the interstitial cells of Cajal was also seen in the background gastric and small intestinal walls. Somatic mutational analysis of the KIT gene revealed a substitution at codon 576 in exon 11 (p.Leu576Pro) in all tumors and normal ileal mucosa. The germline nature of this mutation was confirmed by mutation analysis in peripheral blood leukocytes. However, she had no familial history of GISTs and her parents did not carry the respective germline mutation.

Gastrointestinal stromal tumors (GIST) are mesenchymal neoplasms of the gastrointestinal tract (GI) that are defined, in part, by the expression of CD117, a c-Kit proto-oncogene protein. GISTs emerge outside of the GI at a very low frequency, typically in a single organ or location. GISTs that occasionally emerge outside of the GI are classified as extra-gastrointestinal stromal tumors (EGIST). The present study reports an extremely rare case of EGIST detected in the pancreas and the liver. The pancreatic and liver tumors were 4.5×2.5 cm and 2.0×1.5 cm in size, respectively. Both tumors consisted of CD117-positive spindle cells with a similar mitotic rate of 1-2 per 50 high power fields. The pancreatic and the hepatic EGISTs were at a low risk of malignancy, and both tumors were proposed to be primary stromal tumors. To the best of our knowledge, this is the first report of likely primary EGIST identified in the pancreas and liver of the same patient.

A patient with early achalasia presented spontaneous strong rhythmic non-propulsive contractions at ~7/min, independent of swallows. Our aim was to evaluate characteristics of the rhythmic contractions, provide data on the structure of pacemaker cells in the esophagus and discuss a potential role for interstitial cells of Cajal (ICC) in the origin of rhythmicity. We hypothesize that intramuscular ICC (ICC-IM) are the primary pacemaker cells. The frequency but not the amplitude of the rhythmic contractions was inhibited by the phosphodiesterase inhibitor drotaverine consistent with cAMP inhibiting pacemaker currents in ICC-IM. The frequency increased by wet swallows but not dry swallows, consistent with stretch causing increase in slow wave frequency in ICC-IM. New studies on archival material showed that ICC-IM were present throughout the human esophageal musculature and were not diminished in early achalasia. Although ICC-IM exhibited a low density, they were connected to PDGFRα-positive fibroblast-like cells with whom they formed a dense gap junction coupled network. Nitrergic innervation of ICC was strongly diminished in early achalasia because of the loss of nitrergic nerves. It therefore appears possibly that ICC-IM function as pacemaker cells in the esophagus and that the network of ICC and PDGFRα-positive cells allows for coupling and propagation of the pacemaker activity. Loss of nitrergic innervation to ICC in achalasia may render them more excitable such that its pacemaker activity is more easily expressed. Loss of propagation in achalasia may be due to loss of contraction-induced aboral nitrergic inhibition.

Ramon y Cajal discovered a particular cell type in the gut, which he named \'interstitial neurons\' more that 100 years ago. In the early 1970s, electron microscopy/electron microscope (EM) studies showed that indeed a special interstitial cell type corresponding to the cells discovered by Cajal is localized in the gut muscle coat, but it became obvious that they were not neurons. Consequently, they were renamed \'interstitial cells of Cajal\' (ICC) and considered to be pace-makers for gut motility. For the past 10 years many groups were interested in whether or not ICC are present outside the gastrointestinal tract, and indeed, peculiar interstitial cells were found in: upper and lower urinary tracts, blood vessels, pancreas, male and female reproductive tracts, mammary gland, placenta, and, recently, in the heart as well as in the gut. Such cells, now mostly known as interstitial Cajal-like cells (ICLC), were given different and confusing names. Moreover, ICLC are only apparently similar to canonical ICC. In fact, EM and cell cultures revealed very particular features of ICLC, which unequivocally distinguishes them from ICC and all other interstitial cells: the presence of 2-5 cell body prolongations that are very thin (less than 0.2 mum, under resolving power of light microscopy), extremely long (tens to hundreds of mum), with a moniliform aspect (many dilations along), as well as caveolae. Given the unique dimensions of these prolongations (very long and very thin) and to avoid further confusion with other interstitial cell types (e.g. fibroblast, fibrocyte, fibroblast-like cells, mesenchymal cells), we are proposing the term TELOCYTES for them, and TELOPODES for their prolongations, by using the Greek affix \'telos\'.

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