Approximately 25% of appendiceal mucinous neoplasms are asymptomatic and found incidentally on abdominal imaging or at surgery[
3]. Rare clinical manifestations of these tumors are intestinal obstruction, intussusception, gastrointestinal bleeding and extrinsic ureteral compression. In a series of 141 patients who underwent urgent appendectomy for suspected acute appendicitis, 4 patients were found to have a mucinous neoplasm of the appendix on final pathology[
4]. The classification and nomenclature of appendiceal mucinous neoplasms have not been confirmed. Classical division of these tumors into cystadenoma and cystadenocarcinoma is not necessarily suitable because Prayson and colleagues reported a series of 19 patients with pseudomyxoma peritonei, confirmed by malignant epithelium in peritoneal implants, where greater than 75% had only mucinous cystadenomas of the appendix as the primary lesion[
5]. These findings were repeated in another report, in which a mucinous cystadenoma without atypical epithelium was accompanied by pseudomyxoma peritonei[
6]. Recently, Pai and colleagues stratified appendiceal mucinous neoplasms into four distinct groups based on reassessment of pathologic features and long-term follow-up of 116 patients who underwent resection of appendiceal neoplasms[
7]. According to their classification, the low-grade noninvasive mucinous neoplasms, all of which have been called cystadenoma, were split into three groups. Group 1 is mucinous adenoma that is confined to the appendix; Group 2 is mucinous neoplasm with low-grade dysplasia that is confined to the appendix associated with extra-appendiceal acellular mucin; and Group 3 is mucinous neoplasm with low-grade dysplasia with extra-appendiceal neoplastic epithelium. Group 4 is mucinous cystadenocarcinoma with high-grade cytology, complex architecture, or invasion. After a long-term follow-up, mucinous adenoma (Group 1) never recurred and tumors in Group 2 rarely recurred irrespective of the types of surgery, whereas in Group 3 the 5-year disease-free survival rate was 25% and in Group 4 it was 20%. Our case was classified as Group 2, low-grade mucinous neoplasm without extra-appendiceal spread. For appendiceal mucinous neoplasms, various surgical procedures such as simple appendectomy, appendectomy with partial resection of the cecum, ileocecal resection and right hemicolectomy have been performed using an either open or laparoscopic approach. The principle of surgery is complete excision of the tumor without any spillage of mucus-containing tumor cells in the peritoneal cavity. Although the size of the tumor is not likely to help in the differential diagnosis of mucinous neoplasms[
7], the procedure of choice seems dependent on tumor size. We chose ileocecal resection rather than right hemicolectomy because even if the tumor is diagnosed as a cystadenocarcinoma on subsequent histopathological examination, it rarely spreads by the lymphatics[
8]. Since synchronous appendiceal mucinous neoplasms and colon cancer or adenoma are not uncommon, examination of the large intestine should be done with full colonoscopy[
9]. Recently, the coexistence of ileal endometriosis and carcinoid tumor of the appendix was reported[
10], but a case of appendiceal mucinous neoplasm with concurrent ileal endometriosis has not been reported.
Intestinal endometriosis may be more frequent than expected, but the involvement of the terminal ileum is rare. There were 163 cases of bowel endometriosis (5.4%) among 3037 laparotomies for endometriosis, and resections of the ileum and/or cecum were performed in 11 cases, whereas a colectomy was needed in 30 cases[
11]. In another report on patients with intestinal endometriosis, 72.4% had involvement of rectosigmoid, 13.5% of the rectovaginal septum, and 7% of the distal ileum[
12]. The classical symptom of dysmenorrhea due to endometriosis may be absent if the bowel is exclusively involved. The superficial intestinal endometriosis may be asymptomatic, but the clinical features of a subset of intestinal endometriosis are progressive, leading to subsequent serious complications such as intestinal obstruction[
13,
14] and perforation[
15] requiring emergency surgery.