adenocarcinoma of the vermiform appendix is a rare neoplasm of the gastrointestinal tract with an incidence of about 0.1% to 0.2% . age - adjusted incidence of cancer of the appendix is 0.12 cases per 1 000 000 per year . these rare tumors are seldom suspected before surgery , and < 1/2 are diagnosed intraoperatively . the most common presentation of appendiceal malignancy is right lower abdominal pain that often mimics acute appendicitis . right iliac fossa mass and intestinal obstruction have also been reported ; these presentations reflect various stages of a locally expanding tumor causing luminal obstruction of the appendix . there are other clinical presentations , and we report herein a case of appendicular adenocarcinoma found unexpectedly in a patient who presented to the gastroenterology unit with per - rectal bleeding . the patient is a 55-year - old lady admitted with rectal bleeding due to the penetration of mucinous adenocarcinoma of the appendix into the sigmoid colon . based on a review of the literature , this is the first reported case of an appendiceal malignancy presenting and being treated in this manner . we diagnosed a case of appendicular mucinous cystadenocarcinoma found unexpectedly in 55-year - old lady admitted to the gastroenterology unit because of per rectal bleeding and a rectal polyp suspected on an outpatient colonoscopy . colonoscopy revealed evidence of external compression in the rectosigmoid junction with tumor infiltration of the sigmoid mucosa . in the rest of the colon , there was a small polyp in the ascending colon that was removed by snaring . gastrografin enhanced ct - scan after per rectal filling and maximal distension of the rectum and sigmoid colon revealed a tightly stenosed 6.5-cm lumen in the distal part of the sigmoid colon . specifically , this segment of the sigmoid colon was infiltrated by a 6 cm  6 cm large hypodense irregular tumor mass that also infiltrated part of the adjacent ileum . this tumor mass was connected to the end of the appendix , which had a diameter of 1.2 cm ( figure 1 ) . computed tomographic scan showing sigmoid colon infiltrated by 6 cm  6 cm large hypodense irregular tumor mass connected to the end of the appendix . the clinical investigations , ct and colonoscopy , indicated the possibility of appendicular carcinoma with an infiltrated sigmoid colon . a laparoscopic sigmoid colectomy was performed first . with the patient in the supine position , pneumoperitoneum was established with the so - called open technique , and 4 trocars were placed in the upper , lower , left , and right abdomen . the chief surgeon operated from the right side via the first monitor placed at the left side of the patient , and the assistant was on the left side . exploration of the abdomen showed a conglomerate tumor in the pelvis with involvement of the cecum and sigmoid colon . for sigmoid and right colon resection , we mobilized , devascularized , divided , and resected the colon intracorporeally . the retroperitoneum was incised medial to the left ureter , and the left hypogastric nerve was cautiously identified . after the sigmoid colon had been mobilized , 2 mesenteric windows were created at the sigmoid mesentery , one at the level of the rectosigmoid junction , and the second at the midsigmoid level . the inferior mesenteric vessel was divided with a vascular stapler , and the mesosigmoid was dissected up to the proximal part of the sigmoid colon . after that , the distal part of the sigmoid colon and the proximal rectum were mobilized under the tumor mass attachment . following this , we mobilized the right colon as described previously . the chief surgeon operated from the left side of the patient , and the endoscope was placed into the left paraumbilical trocar . to carry out the lymphadenectomy simultaneously with the resection of the vascular stem , primarily the laterally running ileocolic / right colic arteries and the branches of the superior mesenteric artery were sought out , exposed , and ligated using a window technique . the laterocaudal mobilization extended to the cecal pole and the terminal ileum , cranially to the ascending and meso - ascending colon until the mesenteric root in the outflow area of the lateral colonic vessels . after the terminal ileum was mobilized , the ileum was divided with a stapler . at this stage , the tumor mass including the sigmoid colon and fully mobilized cecum and distal part of the sigmoid colon under the tumor were well visualized and easily divided . with this action as the preparation was advanced cranially , the lateral abdominal wall ties were released , at first , using the ultrasonic dissector or scissors step - by - step until the flexure . then , the ascending colon was released of its retroperitoneal ties . with a properly layered dissection towards the aorta between the posterior side of the meso ascending colon and the renal fascia , the preparation was continued until the horizontal part of the duodenum came into view and the stump was detached from its mesenteric ties . a dissection rod was indispensable for the traumatic dissection , because the embryonically preformed tissue strands were best detached from one another by blunt dissection . with detachment of the right colonic flexure , the status of the already mobilized colomesenteric segment changed in such a way that a caudal dissection of the flexure could become complicated , eg , at the vascular stems , due to visual obstruction by the falling intestinal convolution . after complete mobilization of the right - sided colon intended for resection , the pneumoperitoneum was released , the trocar removed , and the incision extended for minilaparotomy . externalization of the prepared sigmoid and right colon was carried out through a foil ring introduced into the minilaparotomy over the symphysis pubis for wound protection . after the right transverse colon was divided extracorporeally and the specimen removed , the distal ileum was exteriorized ( figure 2 ) . after the anvil was placed in the descending colon , then retained into the abdomen , the incision was closed . we placed the stapler through the rectum and mated it with the anvil laparoscopically to complete the colorectal anastomosis . first flatus was recognized on the second postoperative day , a solid diet was started on the third postoperative day , and the patient was discharged and went directly home on the eighth postoperative day ( figure 4 ) . histopathological examination showed mucinous adenocarcinoma of the appendix with infiltration of the sigmoid colon of about 6 cm ( figure 3 ) . the patient seen 2 months after surgery was in good general condition with no complications . a laparoscopic sigmoid colectomy was performed first . with the patient in the supine position , pneumoperitoneum was established with the so - called open technique , and 4 trocars were placed in the upper , lower , left , and right abdomen . the chief surgeon operated from the right side via the first monitor placed at the left side of the patient , and the assistant was on the left side . exploration of the abdomen showed a conglomerate tumor in the pelvis with involvement of the cecum and sigmoid colon . for sigmoid and right colon resection , we mobilized , devascularized , divided , and resected the colon intracorporeally . the retroperitoneum was incised medial to the left ureter , and the left hypogastric nerve was cautiously identified . after the sigmoid colon had been mobilized , 2 mesenteric windows were created at the sigmoid mesentery , one at the level of the rectosigmoid junction , and the second at the midsigmoid level . the inferior mesenteric vessel was divided with a vascular stapler , and the mesosigmoid was dissected up to the proximal part of the sigmoid colon . after that , the distal part of the sigmoid colon and the proximal rectum were mobilized under the tumor mass attachment . following this , we mobilized the right colon as described previously . the chief surgeon operated from the left side of the patient , and the endoscope was placed into the left paraumbilical trocar . to carry out the lymphadenectomy simultaneously with the resection of the vascular stem , primarily the laterally running ileocolic / right colic arteries and the branches of the superior mesenteric artery were sought out , exposed , and ligated using a window technique . the laterocaudal mobilization extended to the cecal pole and the terminal ileum , cranially to the ascending and meso - ascending colon until the mesenteric root in the outflow area of the lateral colonic vessels . after the terminal ileum was mobilized , the ileum was divided with a stapler . at this stage , the tumor mass including the sigmoid colon and fully mobilized cecum and distal part of the sigmoid colon under the tumor were well visualized and easily divided . with this action as the preparation was advanced cranially , the lateral abdominal wall ties were released , at first , using the ultrasonic dissector or scissors step - by - step until the flexure . then , the ascending colon was released of its retroperitoneal ties . with a properly layered dissection towards the aorta between the posterior side of the meso ascending colon and the renal fascia , the preparation was continued until the horizontal part of the duodenum came into view and the stump was detached from its mesenteric ties . a dissection rod was indispensable for the traumatic dissection , because the embryonically preformed tissue strands were best detached from one another by blunt dissection . with detachment of the right colonic flexure , the status of the already mobilized colomesenteric segment changed in such a way that a caudal dissection of the flexure could become complicated , eg , at the vascular stems , due to visual obstruction by the falling intestinal convolution . after complete mobilization of the right - sided colon intended for resection , the pneumoperitoneum was released , the trocar removed , and the incision extended for minilaparotomy . externalization of the prepared sigmoid and right colon was carried out through a foil ring introduced into the minilaparotomy over the symphysis pubis for wound protection . after the right transverse colon was divided extracorporeally and the specimen removed , the distal ileum was exteriorized ( figure 2 ) . side - to - side ileotransverse anastomosis was performed with a linear stapler . en bloc resection of the sigmoid and right colon . after the anvil was placed in the descending colon , then retained into the abdomen , the incision was closed . we placed the stapler through the rectum and mated it with the anvil laparoscopically to complete the colorectal anastomosis . first flatus was recognized on the second postoperative day , a solid diet was started on the third postoperative day , and the patient was discharged and went directly home on the eighth postoperative day ( figure 4 ) . histopathological examination showed mucinous adenocarcinoma of the appendix with infiltration of the sigmoid colon of about 6 cm ( figure 3 ) . the patient seen 2 months after surgery was in good general condition with no complications . primary adenocarcinoma of the appendix is a rare neoplasm of the gastrointestinal tract and constitutes about 0.5% of all gastrointestinal tract tumors . these rare tumors are seldom suspected before surgery , and less than one - half are diagnosed intraoperatively . several studies describing primary tumors of the appendix have appeared in the literature since 1903 , when elting published a review and case series . there are 4 major histological subtypes : cystic , colonic , carcinoid , and adenocarcinoid . carcinoids are most common , constituting nearly 90% of all the primary tumors of the appendix . macroscopically , they produce mucin - filled cystic dilatation of the appendix indistinguishable from that associated with benign tumors . diagnosis of malignancy is made using 2 features : invasion of the appendicular wall and identification of epithelial cells in peritoneal mucous collections . spread of the neoplasm above the diaphragm or invasion of the abdominal viscera is exceptional , and lymphatic and hematogenous spread is also very rarely seen . sometimes this tumor may present in an unusual manner like polyploidy infiltration of the abdominal wall , bladder infiltration mimicking bladder carcinoma , cecocecal intussusceptions , retroperitoneal abscess , vaginal hydronephrosis , or per - rectal bleeding . sometimes they may present with distension of the abdomen due to pseudomyxoma peritoneum and obstruction of the gut due to involvement of the colon . even if an appendicectomy has been performed previously , cystadenocarcinoma of the appendicular stump may develop ; therefore , the possibility of carcinoma in the appendicular stump that increases in size should be born in mind . accurate and complete preoperative diagnosis has been rare in the past , but modern imaging techniques today allow us to recognize most of the complications and associated conditions . also in such advanced cases with clear preoperative examination , it should not to be considered a contraindication to performing laparoscopic surgery . due to intraperitoneal spread of the appendicular carcinoma , invasion of the abdominal viscera , as in our case , and the poor prognosis of this tumor , an aggressive approach should be taken when treating patients with this type of tumor . further development of instruments and techniques has made it possible to apply laparoscopic surgery to malignant diseases in such complex cases as we have described . compared with conventional surgery , laparoscopic surgery is beneficial with respect to short - term outcomes , including earlier recovery and less need for postoperative analgesia . radiotherapy , chemotherapy , and new therapeutic modalities like radioimmunotherapy and matrix metalloproteinase inhibitors have still to be proven by prospective analysis .