Mucoceles of the appendix mimicking ovarian cysts

Abstract

Background: This review focuses on appendiceal mucoceles that have been reported to incidentally mimic ovarian cysts and put the patient at risk of misdiagnosis and, thus, inadequate treatment.

Methodology: Review of the literature.

Principal findings: Benign mucoceles are the most common form of appendiceal mucoceles and represent about 63-84%, whereas a malignancy is found in 11-20%. Patient presentation is extremely variable for all forms, with, first and foremost, nonspecific symptoms, and patients may also be completely asymptomatic. Thus, the majority of appendiceal mucoceles are discovered incidentally. Women with ovarian cysts also frequently report abdominal pain or nonspecific gastrointestinal symptoms, with about 10% of patients being asymptomatic. Gynecologists perform transvaginal ultrasound as a standard procedure to evaluate pelvic tumors from the uterus, tubes, or ovaries. The ultrasound appearance of appendiceal mucoceles can vary widely from well-encapsulated purely cystic lesions with anechoic fluid, hypoechoic masses with fine internal echoes, or complex hyperechoic masses. Thus, they can mimic ovarian cysts. However, a specific ultrasonographic marker is the so-called “onion skin sign” and its “dumbbell structure”. Even when an appendiceal mucocele is detected during gynecologic surgery, the appropriate surgical treatment would be an open approach, ideally combined with an intraoperative frozen section examination. The gynecologist might choose not to continue with the operation, instead performing the excision of the appendiceal mucocele as a two-step procedure.

Conclusion/Significance: We advise gynecologists to consider the possibility of an appendiceal neoplasm, especially when a dumbbell structure in the lower right abdomen is found on ultrasound. If an appendiceal mucocele is incidentally diagnosed during surgery, a laparotomic approach is recommended if the operation is continued. This should be performed by a general surgeon.