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Torsion of a mucocele of the vermiform appendix: a case report and review of the literature

Torsion of a mucocele of the vermiform appendix is an extremely rare condition and also a rare cause of an acute abdomen with a clinical presentation that is indistinguishable from acute appendicitis, and thus, the condition is diagnosed during operation. Here, the authors describe the case of a 78-year-old female, who presented with intermittent abdominal pain. The appendix had a pelvic position and the torsion was counterclockwise. In addition, the torsion was associated with mucocele of the appendix, which was considered a secondary factor of torsion. Appendectomy and drainage were performed.


INTRODUCTION
Appendicular torsion, which was first described by Payne in 1918, is an infrequent cause of acute abdomen syndrome. Despite its rarity, sufficient cases have been reported in the literature to affirm that its presentation is practically identical to acute appendicitis [1]. Torsion of the appendix could be a primary event or an event secondary to other pathologies. In cases of primary torsion, a specimen examination shows secondary ischemic or necrotic change and luminal dilatation distal to the torsion site without any primary lesion. Gopal et al. [2] postulated that the contributing factors are a long appendix and a fan-shaped mesoappendix with a narrow base, which is usually attached to the appendix laterally. On the other hand, secondary torsion is caused by an appendiceal abnormality, such as, fecalith [3], cystadenoma [4], mucocele [5], a carcinoid tumor [5], adhesion [6], or lipoma [7]. Here, we report a case of secondary torsion of the vermiform appendix with mucocele, and review the literature on secondary appendiceal torsion.

CASE REPORT
A 78-year-old female patient presented to the emergency room complaining of intermittent abdominal pain for 6 days, accompanied by nausea and vomiting for 2 hours. Her medical history included well-controlled diabetes mellitus for 15 years and no previous abdominal S48 thesurgery.or.kr     3). Histopathology showed that the lumen of the appendix was dilated and contained large amounts of mucus-like material, but there was no evidence of malignancy (Fig. 4).
The postoperative course was uncomplicated, and the patient was discharged fourteen days later in good general condition.

DISCUSSION
Torsion of the vermiform appendix is a rare condition that clinically simulates acute appendicitis. The condition is indistinguishable preoperatively from acute appendicitis and it is invariably diagnosed intraoperatively [8]. The site of torsion is variable and could be at the base or about 1 cm or more distal to the base [8]. Furthermore, the position of the appendix is variable, but is usually described as free-lying or pelvic (as in our case) [2].
Primary and secondary torsion of the vermiform appendix have been described. Primary torsion appears to be associated with anatomical variations, such as, a narrow base, a long appendix, or a fan-shaped mesoappendix [9].
Primary torsion of the vermiform appendix remains a rare finding that is usually found at surgery under another di-agnosis-most commonly acute appendicitis. The origin of primary torsion remains unknown. Among cases with acute inflammation, the inflammatory response has been deemed an event secondary to torsion, rather than a precipitating cause [10]. On the other hand, secondary torsion has been reported to be associated with appendiceal abnormalities, such as, fecalith, cystadenoma, mucocele, car- In conclusion, torsion of the vermiform appendix is a rare disorder with an unclear etiology, and causes abdominal symptoms clinically indistinguishable from acute appendicitis. Its presentation is so variable that preoperative diagnosis is extremely difficult, and it is treated by appendectomy. Although appendicitis is the most common intra-abdominal surgical emergency, torsion of the vermiform appendix has only rarely been described, and is an uncommon cause of an acute abdomen. When a patient presents with abdominal pain indicating appendicitis, torsion of the vermiform appendix should be considered in the differential diagnosis.

CONFLICTS OF INTEREST
No potential conflict of interest relevant to this article was reported.