Endometriosis of the Appendix: Incidental Diagnosis

Introduction

Endometriosis is the presence of ectopic endometrial tissues outside the lining of the uterine cavity. ¹ It is a well-known cause of chronic pelvic pain and infertility. Endometriosis of the appendix is rare, and may present with acute or chronic abdominal pain. Preoperative diagnosis is difficult. The definitive diagnosis is usually established following histopathologic examination of appendix. Laparoscopy is the procedure of choice for the diagnosis and surgical treatment of endometriosis. ²

Case

A 37-year-old woman (para 2) came to the outpatient department (OPD) at the Post Graduate Institute of Medical Sciences with primary complaints of having had pain in the lower abdomen and menorrhagia for the past year. The pain was a dull aching, continuous, and located in the suprapubic area, and was aggravated during menstruation. Menstrual cycles lasted for 10 days at 28-day interval and flow had been increased during the past year. There were no bladder or bowel complaints. On examination, there was a mass of 10×10 cm, arising from pelvis and extending to left iliac fossa. The mass was nontender, with limited mobility, and firm-to-cystic in consistency.

On sonography of the abdomen, the liver, spleen, gallbladder, bilateral kidneys, ureter, and bladder were normal. There was no evidence of renal calculi or hydronephrosis. The uterus was of normal size, and endometrial thickness was 10 mm. There was no evidence of any fibroid or adenomyosis. Hypoechoic lesions were present in both the ovaries, 4×4 cm on the right side and 13×10 cm on the left side, showing flow on color Doppler imaging. Per the protocol, endometrial sampling was performed to account for the menorrhagia, which revealed a secretory phase. Urine examination did not reveal any abnormality. As the patient did not have any symptoms or signs pertaining to the gastrointestinal (GI) tract, endoscopy and barium studies were not performed. A provisional diagnosis of bilateral ovarian cyst was made. The patient was scheduled for laparoscopy. Perioperatively, there was found to be a 12×15 cm ovarian cyst on the left side, which was adherent to the sigmoid colon, pushing it anteriorly. The contents of the cyst were chocolate-colored. The right ovary had a cyst 4×4 cm in size, adherent to the appendix, over which two firm nodules were also noted. Total abdominal hysterectomy with bilateral salpingo-oopherectomy was performed after mobilizing the sigmoid mesocolon of the adjacent structures. In view of the firm nodules on the appendix, appendectomy was performed. No lesion suggestive of endometriosis could be demonstrated anywhere else in the pelvis or in any other part of the intestine.

On histopathologic examination (Fig. 1), there were endometrial glands and hemosiderin-laden macrophages in the appendicular stroma, and a hemorrhagic cyst and focal endometrial lining were present in both the ovaries, suggestive of endometriosis. The uterus showed endometrium in the secretory phase; the myometrium, cervix, and fallopian tubes were unremarkable.

OPEN IN VIEWER

FIG. 1

Section of appendix showing endometrial glands (arrow) in stroma of the appendix (solid arrow). Hematoxylin and eosin stain, original magnification×10.

Results

The postoperative period was uneventful. She reported to the OPD after 1 month and then after 6 months for follow-up, and was found to be free of pain.

Discussion

Endometriosis, defined as the presence of endometrial glands and stroma outside the uterine cavity, is estimated to affect 4%–50% of women of reproductive age, and results in pelvic pain and infertility in up to 50% of these patients. Symptoms of the disease may often be manifested by the location of lesion, for example, increased dyspareunia with vaginal or uterosacral endometriosis. In addition to the pelvic location, endometriosis of the GI tract may cause a wide array of symptoms and is involved in 3%–4% of patients affected by endometriosis. ³ Endometriosis of the appendix is uncommon. The incidence of appendiceal endometriosis in patients of endometriosis is 2.8%. ⁴ Involvement of appendix may present as appendicitis, mucocele of appendix, or appendicular mass that may mimic neoplasm. Perforation of the appendix may occur, especially during the first two trimesters of pregnancy.

In this patient, a provisional diagnosis of ovarian endometriosis was made preoperatively, but appendicular endometriosis was found to be incidental, as the patient did not have any features suggestive of GI involvement.

In one study of 200 consecutive endometriosis operations with routine appendectomy, three occurrences of macroscopic appendiceal endometriosis were identified and proven on microscopic examination. In situ microscopic endometriosis without macroscopic disease was not encountered. ⁵ In contrast, another study including 106 patients with routine appendectomy during laparoscopic treatment of ovarian endometriosis has shown gross abnormality in 2.3% of patients, whereas microscopic examination has shown appendicular endometriosis in 13.2% of patients. ⁶

In this patient, endometriotic nodules were present on the appendix, which was confirmed on histopathologic examination.

Diagnosis of endometriosis is based on histologic examination showing two of the following three characteristic signs: intrauterine glands, stroma cells, or hemorrhage. ¹ If the standard pathologic examination fails to demonstrate the endometrial tissue, appendicular endometriosis can be suspected by marked increase in the number of mast cells in the muscularis propria which is known as “catamenial appendicitis”.

Conclusions

Despite the low prevalence of appendiceal disease, patients undergoing surgery for right lower quadrant pelvic pain or endometriosis should be counseled regarding the possibility of appendectomy. ⁴ In addition, the appendix and other abdominopelvic locations must be inspected for disease, and treated.