Appendiceal mucocele presenting with lower abdominal pain

A 57-year-old man was referred to our hospital with a 3-day history of right lower abdominal pain. He denied having fever, bloody stool, or weight loss. An abdominal ultrasound carried out elsewhere demonstrated a mass lesion in the right lower abdomen. On examination the right lower abdomen was tender without muscle guarding or rebound tenderness. The results of laboratory tests showed unremarkable abnormalities. An abdominal computed tomography (CT) scan demonstrated a 3-cm tumor in the region of the cecum, adjacent to the ileocecal valve ([Fig. 1]). A subsequent colonoscopy demonstrated an erythematous, soft mass with a central crater, located in the site of the appendix ([Fig. 2]). The patient was referred to the department of surgery for a laparotomy. At laparotomy, a tumor, 3 × 3 × 5 cm in size, was identified in the appendiceal area, adherent to the cecum and the terminal ileum. Histopathological examination of the resected tumor revealed multiple foci of mucin deposits without epithelial cells ([Fig. 3]). On the basis of the pathological findings, a diagnosis of appendiceal mucocele was made.

Fig. 1 Abdominal computed tomography scan demonstrated a 3-cm round tumor in the cecal region, adjacent to the ileocecal valve (arrow).

Fig. 2 Colonoscopy showing an erythematous, soft mass at the site of the appendix with a central crater.

Fig. 3 Histopathological section of the resected tumor showing multiple foci of mucin deposits without epithelial cells (hematoxylin and eosin; magnification × 40).

The term appendiceal mucocele denotes an obstruction of the appendiceal lumen with accumulation of mucus distal to the obstruction [1]. It is an infrequent condition, with a prevalence of 0.2 % – 0.3 % in appendectomy specimens [2]. Based on the histopathology, appendiceal mucoceles are divided into three types: mucosal hyperplasia, mucinous cystadenoma, and malignant mucinous cystadenocarcinoma [1]. Preoperative diagnosis of this disease is difficult, and most of these tumors are noted as incidental findings at surgery. They are usually asymptomatic; symptoms and signs, if present, include abdominal pain, hemorrhage, obstruction, and palpable mass. Abdominal ultrasound and CT are effective diagnostic modalities for appendiceal mucocele [3]. Endoscopically, the tumor may be detected as a submucosal mass or cystic mass [4]. Appendectomy is the treatment of choice for a simple appendiceal mucocele [5].

Endoscopy_UCTN_Code_CCL_1AD_2AJ

References

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• 2 Dachman A, Lichtenstein J, Friedman A. Mucocele of the appendix and pseudomyxoma peritonei.  AJR Am J Roentgenol. 1985;  144 923-929
• 3 Madwed D, Mindelzun R, Jeffrey Jr R B. Mucocele of the appendix: imaging findings.  AJR Am J Roentgenol. 1992;  159 69-72
• 4 Zanati S A, Martin J A, Baker J P. et al . Colonoscopic diagnosis of mucocele of the appendix.  Gastrointest Endosc. 2005;  62 452-456
• 5 Dhage-Ivatury S, Sugarbaker P H. Update on the surgical approach to mucocele of the appendix.  J Am Coll Surg. 2006;  202 680-684