Pelvic floor encysted collection

Case contributed by Mohamed Mahmoud Elthokapy


History of trauma (2 weeks ago) fall on her buttocks, then suffered progressive gluteal pain and right perianal swelling with difficult defecation.

Patient Data

Age: 55 years
Gender: Female

A large well-defined midline and right para-midline bilocular oblong shaped encysted collection is seen at the perineum, traversing the pelvic floor, extending to the deep pelvic region, and crossing the urogenital diaphragm at the right para-vaginal recess. It elicits relatively intermediate to high signal T1, and high T2 with fluid-fluid level (dependent hemorrhagic signal as well as signal voids inside), It measures collectively about 7x8.5x15.3 cm in its maximum anteroposterior, side-side, and craniocaudal dimensions respectively.

The lesion is seen extending inferiorly in the right perineal region causing a large sub-cutaneous contour bulge.

It is seen markedly encroaching on the right ischio-rectal and ischio-anal fossae, indenting and displacing the rectum and anal canal to the left side. Its superior extension is seen filling most of the pelvic cavity displacing the pelvic organs anterosuperior.

No intra-spinal extension.

Normal MR appearance of the examined lower lumbar and sacral spine with anterior angulation of the coccygeal pieces, yet no evidence of marrow infiltration or osseous destruction.

No evidence of pelvic lymphadenopathy.

No ascites.

Case Discussion

The findings are impressive of a deep pelvic encysted collection that is seen traversing the urogenital diaphragm and extending to the perianal region.

Ultrasound-guided aspiration of the collection revealed blood and inflammatory cells suggesting infected/liquified encysted hematoma versus a Morel-Lavallée lesion

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