Presentation
Chronic right lower abdominal pain. According to her gynecologist, the patient is known for right hydrosalpinx on follow-up for two years. MRI for evaluation was requested.
Patient Data
Well-circumscribed tubular cystic structure with thin regular wall located the right pelvic region, contiguous with the base of the cecum measuring 105 x 44 x 40 mm. It displays a low signal on T1, high signal on T2 with no restricted diffusion. No enhancing mural nodule or significant enhancing wall. Minimal free fluid is noted in the pelvic region.
Well-defined cystic mass in the right pelvic region with heterogeneous echotexture composed of numerous hypo-and hyperechoic layers "onion sign".
Few non-enhanced CT cuts were performed after the MRI and ultrasound exam demonstrating the distended fluid-filled appendix with curvilinear mural calcification.
Case Discussion
MRI, CT and ultrasound features are most consistent with appendicular mucocele.
The "onion sign" on ultrasound is considered a highly suggestive appendiceal mucocele.
The curvilinear mural calcification seen on CT suggests the diagnosis but is seen in less than 50% of cases.