Pelvic schwannoma in the right parametrium

Abstract

Neurilemomas are benign usually encapsulated nerve sheath tumors derived from the Schwann cells. These tumors commonly arise from the cranial nerves as acoustic neurinomas but they are extremely rare in the pelvis and the retroperitoneal area (less than 0.5% of reported cases), unless they are combined with von Recklinghausen disease (type 1 neurofibromatosis). We report the case of a 58-year-old female with pelvic schwannoma, 6.5 × 5.5 cm in size, in the right parametrium. This is the first case reported in the literature. Based on the rarity of this tumor and in order to ensure optimum treatment and survival for our patient, we performed laparotomy with total abdominal hysterectomy and en-block tumor excision. A frozen section was taken during the surgery before complete resection of the mass, which was ambiguous. Because of the possibility of malignancy, complete excision of the mass was performed, with pelvic blunt dissection. Histological examination showed a benign neoplasm, originating from the cells of peripheral nerve sheaths; diagnosis was a schwannoma. There were degenerative areas, including cystic degeneration, hemorrhagic infiltrations, ischemic foci with pycnotic cells, and collagen replacement. Pelvic schwannomas are rare neoplasms that can be misdiagnosed. Laparoscopy is a safe and efficient option for approaching benign pelvic tumors and might offer the advantage of better visualization of structures due to the magnification in laparoscopic view, especially in narrow anatomic spaces.

Schwannoma with an uncommon anal location

“…Schwannomas are nerve sheath tumors that arise from almost any anatomical site, but particularly in the peripheral, cranial or visceral nerves ( 1 ). Schwannomas can be found not only in children, but in adults also.…”

“…Malignant schwannomas are usually large, infiltrating and characterized histologically by perineural and intraneural spread; in the present study, mainly benign schwannomas are discussed. Schwannomas have the characteristics of a slow growth rate, no invasion and a low rate of transformation or recurrence following resection ( 1 ).…”

“…They often have a single place of origin and 10% have multiple locations of origin. Schwannomas often arise in the head and neck (~25–40%), but are rarely located in the retroperitoneum (6% of primary retroperitoneal tumors) ( 1 , 2 ). These tumors, although rare, should be considered in the differential diagnosis of slow-growing masses of an anal location, such as lipomyomas.…”

A giant ancient schwannoma mimicking an adnexal mass

“…[5] Although schwannomas are generally <5 cm in diameter, those with a retroperitoneal location may reach a much greater size with slow growth over a long period. [2,6] …”

“…[9] Because of the possibility of malignant degeneration, complete surgical resection is the best form of treatment and recurrence will not develop afterward just like all the gastrointestinal pathologies. [5,6,9–12] In cases of preoperative diagnosis, laparoscopic excision can be made. [5] …”