Mucocele of the appendix: what to expect

Abstract

Mucoceles of the appendix are rare and can have quite variable imaging and clinical presentations, sometimes mimicking an adnexal mass. The underlying cause can be neoplastic or non-neoplastic. The typical imaging appearance of a mucocele of the appendix is that of a cystic structure with a tubular morphology. This structure is defined by having a blind-ending and being contiguous with the cecum. Radiologists should be familiar with key anatomical landmarks and with the various imaging features of mucoceles of the appendix, in order to provide a meaningful differential diagnosis of a lesion in the right lower abdominal quadrant. In addition, a neoplastic mucocele can rupture, resulting in pseudomyxoma peritonei, which will change the prognosis dramatically. Therefore, prompt diagnostic imaging is crucial.

Mucocoele of the appendix

“…Additionally, uterine fibroid, adenomyosis, pelvic inflammatory disease, tubo-ovarian abscess, hydrosalpinx, ruptured ovarian cyst and endometriosis should be excluded in females whilst benign prostatic hypertrophy should be excluded in males preoperatively. 1,10,11 Imaging is critical to avoid misdiagnosis and delayed diagnosis which can avert rupture leading to pseudomyxoma peritonei. 12 Appendiceal mucocele can be diagnosed with ultrasound, CT scan and colonoscopy.…”

“…50% of cases cast acoustic shadows due to dystrophic mural calcifications. 1,10 CT scan is used to study the extent of the disease, identify underlying neoplasm and also confirm specific diagnostic features of appendiceal mucocele which appears as a dilated blind-end tubular structure continuous with the caecum filled with homogenous low-echogenic contents, curvilinear mural calcifications and a diameter more than 1.3cm. 1,5 In case 1, the abdominal CT scan showed an appendiceal mucocoele measuring 4.5cm.…”

“…Additionally, uterine fibroid, adenomyosis, pelvic inflammatory disease, tubo-ovarian abscess, hydrosalpinx, ruptured ovarian cyst and endometriosis should be excluded in females whilst benign prostatic hypertrophy should be excluded in males preoperatively. 1 , 10 , 11 …”

“…It commonly occurs over 50 years of age with conflicting sex preponderance. 1 Four histological types have been described based on the nature of the differentiation of the appendiceal epithelial lining: the retention cyst, mucosal hyperplasia, mucinous cystadenoma and mucinous cystadenocarcinoma. 2 WHO has also classified it into neoplastic (mucinous adenoma, low-grade appendiceal mucinous neoplasm (LAMN) and appendiceal adenocarcinoma) and non-neoplastic (mucosal hyperplasia, simple cyst).…”

Pseudomyxoma Peritonei: An Incidental Diagnosis With Atypical Intraoperative Findings Discovered During a Laparoscopic Cholecystectomy

“…Appendiceal mucoceles are often asymptomatic and are generally found incidentally, which was the case with this patient [ 7 ]. However, once the mucocele ruptures, there are often acute symptoms such as right lower quadrant pain mimicking appendicitis, pelvic pain, or peritonitis [ 8 ]. On the contrary, this patient never experienced symptoms in the lower abdominal quadrants or pelvis; the only pain that he experienced was in the epigastrium and right upper quadrant, which were likely manifestations of his chronic cholecystitis.…”