Cellular schwannoma: a rare presacral tumour.

S (neurilemomas) are benign neurogenic tumours arising from Schwann cells of the peripheral nerve sheath. These tumours have a predilection for the head and neck, extremities and posterior mediastinum. Only 3% of schwannomas occur in the retroperitoneum, constituting approximately 4% of all retroperitoneal tumours. They occur without gender predominance in the 20to 50-year age group and are associated with von Recklinghausen’s disease in 18% of cases. Malignant change is exceedingly rare; however, malignant tumours have been reported, although they are usually associated with von Recklinghausen’s disease. The cellular schwannoma is a wellrecognized variant of schwannoma that, because of its cellularity, mitotic activity and occasional presence of bone destruction, is misdiagnosed as malignant in over 25% of cases. Over 100 cases of cellular schwannoma have been published, with a recurrence rate of less than 5% and no development of metastastic disease. These tumours have a predilection for deep structures: the paravertebral region of the retroperitoneum (32%), pelvis (21%) and mediastinum (23%). We describe the management of 2 patients with presacral cellular schwannoma. The diagnosis was made preoperatively from clinical and radiologic findings, and core-needle biopsy results. Despite the rarity of these tumours it is important that the diagnosis be considered preoperatively by the surgeon and the radiologist interpreting the scans, as well as the pathologist examining the core-needle biopsies. The diagnosis of this benign entity may influence further treatment by limiting surgical invasiveness and avoiding unnecessary adjuvant therapy.