Presentation
Vomiting, lethargy one week in a neonate.
Patient Data
Soft tissue density centered over the pelvis suspicious for a pelvic mass.
Nasogastric tube tip projects at the gastric antrum. Indwelling catheter within the urinary bladder.
Cardiothymic silhouette is normal. Lungs are clear without evidence of nodule or mass. No pleural effusion or air leak.
No pathologically dilated loops of large or small bowel. Gas seen in the rectum.
No definite destructive osseous lesion demonstrated on this radiograph.
Adrenal glands appear unremarkable bilaterally, with expected positions superior to the kidneys. Right kidney measures 5.5cm. Left kidney measures 4.7 cm. Bilateral mild pelvicalyceal dilatation (AP renal pelvic diameter right 11 mm, left 10 mm with prominence of the calyces) and dilatation of both ureters to the level of the pelvis, left ureteric diameter of 5 mm, right ureteric diameter 5 mm (measured distally).
Well-defined, encapsulated, multiloculated mass posterior to the bladder with no internal vascularity and mobile internal low level echoes suggesting predominately cystic contents. Dimensions 51mm craniocaudal x 34 mm AP x 33mm transverse. This mass appears to be displacing the rectum to the left, and abuts anterior aspect anterior sacrum/coccyx.
Bladder volume approximately 60ml with the bladder seen anterior to and extending superior to the pelvic mass which has mass effect on the inferior aspect of bladder. Small amount of echogenic dependent debris within the bladder.
IMPRESSION
1) Multiloculated cystic presacral mass with displacement of the rectum.
2) Bilateral hydronephrosis and hydroureter. Bladder extends superior to the pelvic mass and the mass appears to compress the inferior aspect of bladder. Low level mobile debris within the bladder.
Multilobulated, multiseptated, 29 x 42 x 59 mm pelvic mass. Centrally the cystic areas demonstrate a density of approximately 30 HU.
Septated components are enhancing. No calcification.
Epicenter of the lesion lies just anterior to the sacral vertebral bodies, with subtle scalloping of L5 – S3.
Posteriorly, anterior to S3, the posterior border of the mass is less conspicuous. No definite foraminal widening demonstrated.
Caudally, the mass extends down through the rectovesicular recess, inferior to the level of the pubic symphysis just deep to the perineum, without evidence of infiltration through it. Mass displaces the rectum to the left side without obstructing it.
Anterior to the mass lies the collapsed urinary bladder.
Superiorly the mass extends to an S1 level. Mass effect upon the bilateral ureters is causing bilateral, upstream hydroureter and hydronephrosis. Normal renal cortical thickness and enhancement demonstrated bilaterally.
IDC in situ within the bladder, which contains gas (likely iatrogenic) and is decompressed
- Within the pelvis is a large, well-defined cystic appearing structure measuring 35 x 29 x 60mm (AP x TR x CC) and containing heterogeneous T2 intense fluid, with wall enhancement.
- The lesion appears more serpiginous than loculated, with intrinsic septations, and tapers distally towards the prostate and anterior rectal wall, which is the suspected site of origin.
- The rectum is displaced anteriorly and the sigmoid is displaced to the left and effaced, although there is no overt features of acute obstruction.
- Both the ureters and outflow vessels are splayed laterally by the mass. While the lesion abuts the sacrum from the S3 level to L5/S1, it does not appear to arise from or communicate with any presarcral or cord structures.
- There is no osseous erosions, and no invasion of adjacent tissues or bone. No fistulous connections are appreciated.
The primary lesion causes bilateral hydronephrosis and hydrouterter, which appears similar to recent ultrasound imaging. Renal pelvis dimensions measure 11mm on the left and 10mm on the right, with obvious calyceal dilatation. Distal ureters measure 5mm on the left and 3mm on the right, with abrupt compression at the level of the common iliac arteries as they become compressed by the mass.
Fusiform distal dural sac ectasia extending from the T11 level to S1. There is no scalloping of the vertebrae posteriorly and there is no evidence of cord tethering or external communications. The cauda equina appear displaced anteriorly at this level.
No suspicious lymphadenopathy. No concerning osseous lesion.
IMPRESSION
Serpiginous, fluid-filled cystic pelvic mass which appears to be arising within the region of the recto-vesical space. The appearance and wall topography are reminiscent of bowel wall, however, there is no definite connection to bowel, and it appears to be communicating in close proximity to the prostate.
Bilateral hydroureter and hydronephrosis secondary to extrinsic distal ureteric compression at the level of the CIAs.
Fluoroscopic VCUG was performed which confirmed midline communication between the prostatic urethra and the collection.
Case Discussion
The patient subsequently underwent laparotomy and drainage of the lesion, which was purulent. Histology confirmed an abscess with no malignant features. Hydronephrosis subsequently resolved.
The final diagnosis was an infected giant prostatic utricle cyst / abscess. Giant utricle cysts are rare occurrences in neonates 1, particularly at this size, with infected utricle cysts even less common. UTI is the most likely cause of the initial infection, and the spectrum of findings overlaps with neonatal prostatic abscesses, although there is a paucity of cases in the literature 2.
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