A 60-year-old man presented with complaints of abdominal pain, constipation and urinary urgency since 1 week.
Pelvis ultrasonography revealed a thick-walled cystic lesion with thin internal septations seen in the pelvis in the presacral region, displacing the rectum and urinary bladder anteriorly.
Right mid ureteric calculus causing moderate upstream hydronephrosis (Other findings).
CT KUB showed a well-defined hypodense thick-walled cystic lesion with few tiny calcifications noted in the presacral region. The lesion is seen displacing the rectum anteriorly with maintained fat planes and posteriorly abutting the sacrum with no erosions/destruction.
CE MRI Pelvis showed a large well-defined TI hypointense, T2 iso – hyperintense cystic lesion in the presacral region with few internal fluid levels showing corresponding blooming on GRE and few calcifications. The lesion abuts the sacrum and shows mild extension into right S3 neural foramina abutting right S3 exiting nerve root with mild expansion of neural foramina. On post-contrast study shows cystic component with wall enhancement.
Schwannomas (neurilemomas or neurinomas) are benign neoplasms arising from the nerve sheath. Schwannomas occur predominantly in men aged 20 to 50 years. Sites may vary, but they most commonly occur in the head and neck region as well as flexor tendon sheaths of extremities.
Unusual locations such as the urinary bladder, scrotum and fallopian tubes. Schwannomas occurring in the pelvis are rare and account for only 1% of cases .
These tumours are nonaggressive, slow-growing, solitary neoplasms with an extremely low possibility of malignant transformation or recurrence after excision. They are in general asymptomatic and may grow to a considerable size before becoming symptomatic if they are located in deep-seated structures like the retroperitoneal area. They become symptomatic by local compression of the surrounding viscera or by nerve root compression leading to the nonspecific presenting signs and symptoms such as backache, abdominal or pelvic heaviness or distension.
Schwannomas demonstrate typical MRI features of T1 iso-to-hypointensity, T2 hyperintensity, and postcontrast enhancement. Heterogeneous signal intensity and postcontrast enhancement are suggestive of internal haemorrhage and myxoid/cystic changes .
The main treatment is surgical resection of the mass, which relieves compression of adjacent neural structures, improving pain and other symptoms.
In our case, the cystic lesion was resected and final HPE diagnosis is reported as Schwanomma with cystic degeneration.
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