Gastrointestinal stromal tumor of the small bowel complicated by torsion: A case report.

INTRODUCTION: Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors that originate from the gastrointestinal tract wall. Approximately 20-30 % of GISTs originate from the small intestine. GISTs of the small intestine generally present with a palpable mass, distention, and abdominal pain and may exhibit acute abdomen at the onset. Herein, we describe a rare case of a pedunculated GIST of the small intestine complicated by torsion. PRESENTATION OF CASE: A 69-year-old woman presented with lower abdominal pain. Abdominal contrast-enhanced computed tomography showed a 73 × 62 × 57-mm3 tumor in the pelvic cavity with enhanced margins and reduced contrast. It was presumed that the tumor had caused hemorrhagic infarction. Emergency laparotomy was performed, and the pedunculated tumor was found to be twisted 360° clockwise at the pedicle with hemorrhage and necrosis due to torsion. We performed partial resection of the small intestine including the tumor. Histopathological examination revealed tightly arranged spindle-shaped cells with hemorrhage, congestion, and inflammatory cell infiltration. Immunohistochemical staining showed positivity for CD34, CD117, and DOG1. CONCLUSIONS: Torsion of a pedunculated small intestine GIST, although very rare, requires emergency surgery and should be recognized as a cause of acute abdomen in patients with GIST. Immediate surgery is mandatory if torsion of a small intestinal GIST is suspected because the GIST or intestine may become necrotic owing to hemorrhagic infarction.

Primary spindle cell tumor originating from the liver that was difficult to diagnose.

BACKGROUND: It has been reported that hepatocellular carcinoma (HCC) with spindle cell tumor accounts for 1.8% of all HCCs, but spindle cell tumors that do not show an obvious conventional HCC are extremely rare. In this report, we describe a case of resection of a primary spindle cell tumor of the liver that was difficult to diagnose. CASE PRESENTATION: A 75-year-old man presented with fever and right chest pain. He was suspected of a giant primary diaphragmatic tumor of extrahepatic origin by imaging studies. The preoperative differential diagnosis included benign masses such as myxoid sarcoma and schwannoma, and we planned a diaphragmatic resection. Intraoperatively, however, dissection of the tumor from the liver was not possible, requiring an extended right posterior segmentectomy with combined resection of the diaphragm. The patient had a good postoperative course and 1 year has passed since the surgery with no recurrence. The pathology showed that the mass was located just below the hepatic capsule/parenchymal region and was adherent to the diaphragm, but there was no continuity. The morphology suggested a low-grade mesenchymal tumor such as a solitary fibrous tumor and perivascular epithelioid cell tumor, but immunostaining was negative, making the diagnosis difficult. Although some areas of high proliferative activity were observed, finally, the diagnosis of primary spindle cell tumor of the liver with smooth muscle differentiation was made based on the positive results of muscle markers such as αSMA, desmin, and h-caldesmon. CONCLUSIONS: Spindle cell tumor arising from the liver is so rare that preoperative and pathological diagnosis is often difficult to reach. Although further studies are needed to elucidate and better understand this uncommon clinical entity, we consider that complete resection is necessary for the above case, which may contribute to long-term survival.

A case of appendiceal ganglioneuroma in neurofibromatosis type 1.

BACKGROUND: Neurofibromatosis type 1 is an autosomal dominant inherited disease associated with multiple skin neurofibromas or other neurogenic tumors, such as nodular plexiform neurinoma or cerebrospinal tumor. Gastrointestinal stromal tumors are often complicated in patients with neurofibromatosis type 1, although involvement of the appendix is rare, and there have been few reports of appendiceal ganglioneuroma. CASE PRESENTATION: The patient was a 29-year-old man diagnosed with neurofibromatosis type 1 based on physical findings and his family history. During the follow-up of neurofibromatosis, computed tomography was performed to detect neurological tumors, such as neurofibromas in the brain, spinal cord, and gastrointestinal tract. Computed tomography showed a markedly thickened appendix wall, and an appendiceal tumor was suspected. Laparoscopic appendectomy was performed, and a 50 × 35 mm appendiceal submucosal tumor was resected with a negative resection margin. At histopathological examination, the tumor was diagnosed as ganglioneuroma; it showed short spindle-shaped cells and ganglion cells diffusely infiltrated into the proper muscle layer and fibrous tissue that grew around nerve cells. The patient was discharged on the 5th postoperative day without postoperative complications and was doing well at 13 months following the operation. CONCLUSIONS: Gastrointestinal stromal tumor and neurofibroma are the most common gastrointestinal tumors associated with neurofibromatosis type 1, but ganglioneuroma of the appendix is rare. Appendiceal neurogenic tumors should be considered in patients with neurofibromatosis type 1, and surgical resection is necessary because of the risk of malignancy.

The effect of the particle size of alumina sand on the combustion and emission behavior of cedar pellets in a fluidized bed combustor.

A combustion experiment with cedar pellet fuel was carried out in a semi-pilot scale bubbling fluidized bed combustor. The effects of temperature, fluidized velocity, and bed material particle size on the emission of NOx, CO, and CO2 were investigated. The variations in the temperature profile and gas concentration in the vertical and horizontal directions of the combustor were also studied. The results showed that high temperature can improve the combustion efficiency and decrease CO emission. Moreover, increasing the fluidized velocity suppressed CO formation. In addition to temperature and fluidized velocity, the bed material also played an important role during cedar pellet combustion. Coarse bed materials were better than fine materials. In these test runs, the CO emission varied from 20 to 189 ppm, CO2 emission ranged from 5.7% to 19.5%, while NOx emission was quite stable at about 220 ppm.