Schwannomas are peripheral nerve sheath tumors arising from Schwann cells. They are usually found in head and neck, mediastinum and extremities but rarely found in pelvis. Pelvic schwannomas have a slow growth rate, remain asymptomatic and get incidentally detected.  Materials and Methods: A 54 year old male presented with right loin pain and burning micturation since 2 days. Ultrasonography showed right mid ureteric calculus with a thick walled cystic swelling in presacral region. Digital rectal examination revealed a firm, fixed posterior extra rectal mass. The upper limit of the mass could not be reached. Patient was evaluated and on emergency basis Ureterorenoscopy with right sided DJ stenting was done. CE-MRI of pelvis showed a large well defined T1 hypointense, T2 iso-hyperintense solid cystic lesion in presacral region. Mass effect over rectum and urinary bladder anteriorly. Posteriorly, abutting the sacrum and in close relation with right S3 exiting nerve root – F/S/O Schwannoma. Intraoperatively, cystic swelling noted in presacral region measuring 12×10cm. Entire tumor was excised and its origin from nerve root identified and excised without injuring it.  Results: Histopathological report revealed benign nerve sheath tumor composed of Schwann cells with focal Verocay body formation. Immunohistology confirmed Schwannoma with diffuse positivity of S100 protein in the cytoplasm of tumor cells.  Conclusion: Schwannomas with degenerative changes like cyst formation, calcification and hemorrhage are called as ‘Ancient Schwannomas’. MRI is the most preferred imaging technique. Complete surgical excision remains the treatment of choice. Recurrence rate is usually low with good prognosis.

Keywords : Schwannoma, Nerve Sheath, Schwann Cells.