Melanoma of the rectum： A rare entity

A 41-year-old man presented with a 6-mo history of changed defecation and rectal bleeding. A 3-cm polypoid tumor of the lower rectum was found at rectosigmoidoscopy, which proved to be a leiomyosarcoma upon biopsy. Dissemination studies did not show any metastases. He was underwent to an abdomino-perineal resection （APR）. Histopathology of the specimen showed a melanoma （S-100 stain positive）. Two years after the resection, metastases in the abdomen and right lung were found. He died one and half years later. Primary anorectal melanoma is a rare and very aggressive disorder. According to current data, one should always perform a S-100 stain when anorectal sarcoma is suspected. A positive S-100 stain suggests the tumour to be most likely a melanoma. Subsequently, thorough dissemination studies need to be performed. Depending on the outcome of the dissemination studies, a surgical resection has to be performed. Nowadays, a sphincter-saving local excision combined with adjuvant loco-regional radiotherapy should be preferred in case of small tumors. The same loco-regional control is achieved with less ＂loss of function＂ compared to non-sphincter saving surgery. Only in the case of large and obstructing tumors an abdomino-perineal resection is the treatment of choice.     

Incidence and natural history of dysplasia of the anal transitional zone after ileal pouch-anal anastomosis

PURPOSE: Preservation of the anal transitional zone during ileal pouch-anal anastomosis is still controversial because of the risk of dysplasia and the theoretical risk of associated cancer. Without long-term follow-up data, the natural history and optimal treatment of anal transitional zone dysplasia are unknown. The aim of this study was to determine the long-term risk of dysplasia in the anal transitional zone and to evaluate the outcome of a conservative management policy for anal transitional zone dysplasia. METHODS: Two hundred ten patients undergoing anal transitional zone-sparing ileal pouch-anal anastomosis for ulcerative or indeterminate colitis between 1987 and 1992 and who were studied with serial anal transitional zone biopsies for at least five years postoperatively were included. Median follow up was 77 (range, 60–124) months. RESULTS: Anal transitional zone dysplasia developed in seven patients 4 to 51 (median, 11) months postoperatively. There was no association with gender, age, preoperative disease duration or extent of colitis, but the risk of anal transitional zone dysplasia was significantly increased in patients with prior cancer or dysplasia in the colon or rectum. Dysplasia was high grade in one and low grade in six. Two patients each with low-grade dysplasia detected on three separate occasions underwent mucosectomy 29 and 38 months after detection of low-grade dysplasia, but no cancer was found. The five other patients with dysplasia on one or two occasions were treated expectantly and were apparently dysplasia-free for a median of 72 (range, 48–100) months. CONCLUSIONS: Anal transitional zone dysplasia after ileal pouch-anal anastomosis is infrequent, is most common in the first two to three years postoperatively and may apparently disappear on repeated biopsy. Anal transitional zone preservation did not lead to the development of cancer in the anal transitional zone after five to ten years of follow-up. Long-term surveillance is recommended to monitor dysplasia. If repeat biopsy confirms persistent dysplasia, anal transitional zone excision with neoileal pouch-anal anastomosis is recommended.Presented at the meeting of The American Society of Colon and Rectal Surgeons, San Antonio, Texas, May 2 to 7, 1998.     

内镜黏膜下剥离术治疗直肠病变

目的探讨内镜黏膜下剥离术治疗直肠病变的应用价值。方法对肠镜发现的较大直肠腺瘤和黏膜下肿瘤应用头端弯曲的针形切开刀进行内镜黏膜下剥离术（ESD）治疗：（1）黏膜下注射生理盐水抬高病变，使病变与肌层相分离；（2）预切开病变周围黏膜；（3）剥离病变下方黏膜下层结缔组织，完整切除病变。结果12例低位直肠病变，大小0．6～4．5cm（平均2．8cm），均成功完成ESD治疗。术后11例病理确诊基底和切缘未见病变累及；1例腺癌累及黏膜下层病例接受外科根治手术，手术标本病理未见肿瘤残留。ESD手术时间（自黏膜下注射至完整剥离病变）30～120min（平均52min）。术中出血量平均约75ml，均经电凝、氩离子凝固术和止血夹成功止血，未出现需再次肠镜下治疗的出血。2例剥离深至肌层，出现皮下气肿和少量膈下游离气体，保守治疗好转。9例1个月后肠镜复查，创面基本愈合。结论ESD是治疗消化道病变的新方法，不仅能切除较大的病变，还能提供完整的病理学诊断资料。以往需要外科手术的消化道早期癌和部分黏膜下肿瘤，通过ESD可以达到同样的治疗效果。     

Rectal compliance in females with obstructed defecation

PURPOSE: This study was designed to investigate whether rectal compliance is altered in females with obstructed defecation. METHODS: Eighty female patients with obstructed defecation and 60 control subjects were studied. Rectal compliance was measured with an infinitely compliant polyethylene bag. This bag was inserted in the rectum and inflated with air to selected pressure plateaus (range, 0–60 mmHg; cumulative steps of 2 mmHg with a duration of ten seconds) using a computer-controlled electromechanical barostat system. Volume changes at the levels of distending pressures were recorded. The distending pressures, needed to evoke first sensation of content in the rectum, earliest urge to defecate, and the maximum tolerable volume were noted. RESULTS: In all cases, the compliance curve had a characteristic triphasic (S-shaped) form. The mean compliance curve obtained from the patients was identical to that of the controls. However, the course of the compliance curve fell above the normal range (mean + 2 SD) in 14 patients. In ten (71 percent) of these patients, a large rectocele was seen at evacuation proctography. Such a rectocele was observed in only five patients (7.6 percent) with a normal compliance curve (P<0.001). Eighty percent of the controls experienced earliest urge to defecate during the second phase of the curve. In 75 percent of the patients, this occurred in the third phase. The mean pressure threshold for first sensation, earliest urge to defecate, and maximum tolerable volume were significantly higher in patients compared with control subjects. Ten of the patients experienced no sensation at all in the pressure range between 0 and 60 mmHg. CONCLUSION: In females with obstructed defection, the compliance of the rectal wall is normal.     

Pelvic Nerve Stimulation Evokes Nitric Oxide Mediated Distal Rectal Relaxation in Pigs

Purpose  Pelvic nerve stimulation evokes a complex motility response in the pig rectum with a proximal decrease and a distal increase in cross-sectional area. This study investigated whether the distal increase in the cross-sectional area is because of smooth muscle relaxation mediated by nitric oxide. Methods  The pelvic nerves were stimulated with cuff electrodes in ten chloralose-anesthetized minipigs. Pressure, volume, and cross-sectional areas at five positions in the rectum were obtained during stimulation to examine the effect of N^G-nitro-L-arginine (an inhibitor of nitric oxide synthase) injection. Results  Stimulation evoked a median pressure decrease of 13 cm H₂O (range, 0–27; P < 0.05; n = 10) in the anal canal, a pressure increase of 6 cm H₂O (range,-15 to 30; P < 0.05; n = 10) in the rectum and a decrease of 39 mL (range, 30–63; P < 0.05; n = 6) in rectal volume. Rectal cross-sectional areas decreased 33 percent (range, 5–56; P < 0.02; n = 7) in the proximal part and increased 32 percent (range, 9–67; P < 0.02; n = 8) in the distal part. N^G-nitro-L-arginine eliminated the increase in the distal rectal cross-sectional area (n = 5) and the decrease in anal canal pressure (n = 9) in all tested animals. Conclusion  Pelvic nerve stimulation evokes distal rectal relaxation in pigs, sensitive to N^G-nitro-L-arginine, which suggests that this smooth muscle response is mediated by nitric oxide. This work was supported by grants from the Institute of Experimental Clinical Research, Aarhus University Hospital, Aarhus, Denmark Reprints are not available.     

Primary perivascular epithelioid cell tumor in the rectum: A case report and review of the literature

Perivascular epithelioid cell tumor (PEComa) is a rare collection of tumors arising in a wide array of anatomic locations. It is characterized by the presence of a peculiar population of myomelanocytic marker-positive perivascular epithelioid cells, and is commonly detected in the uterus. The colorectal area is an uncommon site for primary PEComa. In this study, we describe a 17-year-old patient presenting with a rectal polyp. Histologically, the tumor consisted of sheets of round to polygonal epithelioid cells with clear and granular cytoplasm, and a prominent capillary network. Some of the tumor cells were positive for Fontana-Masson staining. Immunohistochemically, the tumor cells were positive for HMB-45, and were negative for cytokeratin, vimentin, S-100 protein, actin, desmin, EMA, CD34, and c-kit. After finding melanosomes or premelanosomes at the ultrastructural level, the diagnosis of PEComa was made. Although PEComa arising within the intestinal tract is unusual and clinically unexpected, PEComa should be considered in the differential diagnosis of rectal polypoid lesions.     

宫颈癌后装放疗时膀胱直肠小肠受照剂量探讨

目的 探讨宫颈癌腔内放疗时不同体积的膀胱、直肠与危及器官受照剂量的关系。方法 选取宫颈癌患者共47例,给予剂量点处方剂量600 cGy的高剂量率腔内后装治疗,用剂量体积直方图(DVH)评价标准计划下不同体积的膀胱、直肠和小肠对相应受照剂量的影响。将膀胱按体积大小分成<80 cm³组、80~120 cm³组和>120 cm³组,直肠按体积大小分成>60 cm³ 组和≤60 cm³组,分析其体积与剂量分布的关系。采用方差分析和t检验方法分析D_{1 cm³}、D_{2 cm³}、D_30%和D_50%。结果 与膀胱体积<80 cm³组相比,80~120 cm³组和>120 cm³组的膀胱D_30%、D_50%受照剂量增高(F=5.074、5.088,P<0.05),小肠D_{1 cm³}和D_{2 cm³}值差异无统计学意义(P>0.05);与直肠体积>60 cm³ 组相比,≤60 cm³组的直肠D_{1 cm³}受照剂量减小(t=-2.045,P<0.05)。结论 宫颈癌近距离放疗时,保持膀胱的适当充盈,直肠体积的减少,可使直肠、膀胱和小肠的受照射剂量均相对降低,从而减少放疗的不良反应。     

Perforation of the rectum and sigmoid colon during barium-enema examination

Perforation of the rectum or sigmoid colon complicated 5 of 2200 barium-enema examinations performed during a 4-year period. Three patients with rectal perforations manifested by air extravasation were successfully treated with intravenous antibiotics and complete bowel rest. Two patients with barium extravasation were treated with immediate operation and colostomy. All five patients recovered. Perforation was found to be associated with a rectal stricture due to ulcerative colitis, a rectal cancer, an incarcerated inguinal hernia, fulminant ulcerative colitis, and a normal colon in an elderly patient. To determine the pressure in the rectum that could potentially be generated during a barium-enema examination, the pressures created by a standard barium delivery set were measured, using 1-meter columns of water, 25 percent diatrizoate sodium (Hypaque^®), 20 percent barium, and 80 percent barium. The columns generated pressures of 70, 85, 95, and 120 mm Hg respectively. Squeezing the delivery bag increased the pressure 21 to 79 percent or a maximum of 55 mm Hg. Colorectal perforation during barium-enema examination that was not accompanied by barium extravasation could be successfully treated nonoperatively. The associated pathology and our studies of pressures generated during a barium-enema examination allow us to suggest that the incidence of colorectal perforation during barium-enema radiography can be reduced by 1) performing proctoscopy prior to barium enema, 2) avoiding the use of the rectal balloon in patients with known rectal lesions, 3) avoiding barium studies in patients with active colitis, 4) avoiding generation of pressure greater than that created by a column of barium suspension of one meter, and 5) using a lower concentration of barium when possible.     

Radiology in investigation of rectal bleeding

Although most causes of chronic anorectal bleeding are diagnosed from clinical or sigmoidoscopic examination, there are a number of conditions not detectable from barium enema studies. Results of colonoscopy are compared to those for single- and double-contrast barium enema examinations, and recommendations are made for increasing diagnostic accuracy. Read at the meeting of the American Society of Colon and Rectal Surgeons, Atlanta, Georgia, June 10 to 14, 1979.     

经自然腔道取标本手术在胃部不同疾病中的研究进展

随着微创技术的不断发展,腹腔镜技术在我国胃肠外科疾病的诊治中得到极大推广。在此基础上,经自然腔道取标本手术（NOSES）结合腹腔镜操作技术及微创理念,既达到了微创,同时美容效果更佳。然而,关于NOSES在胃部疾病的应用报道较少,本文将对NOSES在胃部不同疾病中的研究进展进行综述。