Endometriosis of the appendix presenting as acute appendicitis: Figure 1

As with other types of endometriosis in the intestinal tract, endometriosis of the appendix is generally asymptomatic and is usually discovered incidentally during laparotomy in patients with pelvic endometriosis. When it presents with symptoms they are difficult to differentiate from acute appendicitis. Appendiceal endometriosis may not only cause symptoms of acute appendicitis, but may also present as cyclic and chronic right lower quadrant pain, melena, lower intestinal haemorrhage and caecal intussusception. We report a case of appendiceal endometriosis clinically presenting as acute appendicitis, where the definitive diagnosis was established by histopathological examination of the appendix.

Endometriosis is defined as the presence of endometrial glands and stroma outside the uterine cavity and musculature.1 It affects an estimated 8–15% of menstruating women. Intestinal involvement ranges between 3–34% among women with endometriosis. The most commonly involved intestinal sites are the rectum and sigmoid colon. Endometriosis of the appendix is a rarely seen condition, comprising <1% of pelvic endometriosis cases.2 We report a case of endometriosis of the appendix, in order to highlight this rare entity. CASE PRESENTATION A 39-year-old woman presented to the emergency unit with a 6 day history of right iliac fossa pain. She had no lack of appetite, nausea or vomiting. The abdominal pain had a blunt character with moderate severity. The patient stated that her menses were irregular and painful, and her last menstruation period was 22 days before admission. Abdominal examination showed tenderness, guarding and rebound over the right abdominal lower quadrant. She was apyrexial (36.8°C) and had a normal white blood cell count. Abdominal ultrasonography showed a 30×30 mm intramural leiomyoma of the uterus. However, no pathology was detected during gynaecological consultation. Due to aggravation of her complaints, the patient underwent surgery for a prediagnosis of acute appendicitis, at the end of an 8 h period of observation. During the operation the appendix was found to be hyperaemic and oedematous; no other pathology was detected within the abdomen, and an appendectomy was performed. After the operation, the abdominal symptoms disappeared completely. The patient was discharged on the second day postoperatively without any complications. At the histopathological examination of the appendix, a focus of endometriosis was detected (fig 1). The patient had no early postoperative complaints and was referred to a gynaecologist.

Endometriosis of the appendix constitutes a small percentage of all cases of gastrointestinal endometriosis. Collins reported that the rate of appendiceal endometriosis was 0.05% in 71 000 cases of appendectomy.3 Agarwala and Liu reported finding appendiceal endometriosis in 14 (4.4%) of 378 patients who underwent laparascopic appendectomy for chronic pelvic pain.4 Appendiceal endometriosis is usually asymptomatic, but it occasionally causes cyclic right lower quadrant pain, acute appendicitis, caecal intussusception and lower gastrointestinal haemorrhage. While appendiceal endometriosis may have various clinical presentations, without any specific symptoms it is difficult to make an accurate preoperative diagnosis.5 Also, in our patient we did not detect a specific symptom that would lead us to a diagnosis of appendiceal endometriosis, and she underwent surgery for a prediagnosis of acute appendicitis. It has been reported that appendiceal endometriosis can occur in association with uterine leiomyomas, ovarian endometriosis and menstrual abnormalities.6 Our patient had a 30×30 mm leiomyoma of the uterus, and her menstrual periods were painful and irregular; she had her last period 22 days before the appendectomy, and her symptoms did not coincide with her menstruation. During the operation the appearance of the appendix did not differ from the other acute phlegmonous appendicitis. The diagnosis of appendiceal endometriosis is based on the histological presence of endometrial tissue in the specimen. In their series Mittal et al found that 56% of endometriosis of the appendix involved the body of the appendix, compared to 44% at the tip. They also noted that muscular and seromuscular involvement occurred in two thirds of patients, while the serosal surface was involved in only one third of patients. Mucosa was not involved in their series.7 In our case, endometriosis was situated at the tip of the appendix, with subserosal location, and the mucosa was not involved. This was consistent with the literature.8,9 Khoo et al reported that the acute symptoms resolved totally, but the lower abdominal pain recurred in their case.6 They stated that this condition might be due to the ovarian endometriosis in the patient, and that patients must be followed by a gynaecologist. In our patient, the recurring abdominal pains were also relieved following surgery, and at subsequent gynaecological examination no other endometriosis was detected. Nevertheless, we believe that the gynaecological follow-up should be planned. LEARNING POINTS Appendiceal endometriosis is a rare entity, and its preoperative diagnosis is very difficult. It should be kept in mind as a differential diagnosis in fertile women with acute appendicitis symptoms. During appendectomy, other foci of pelvic endometriosis can be inspected and treated if found. Appendiceal endometriosis is diagnosed definitively by histopathological examination. Appendectomy resolves the acute symptoms, and patients should be followed up by a gynaecologist. Footnotes Competing interests: none. Patient consent: Patient/guardian consent was obtained for publication

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