Retroperitoneal giant ancient schwannoma.

Ancient schwannoma is a rare variant of benign peripheral nerve sheath tumor, often morphologically mimicking malignancy. Retroperitoneum is an uncommon location. We describe one case of giant retroperitoneal ancient schwannoma. Literature concerning this variant is also reviewed. A 65 year old male presented with altered bowel habits. Imaging findings revealed a large heterogeneous mass in the retroperitoneum. The patient was treated with complete excision. Grossly, the tumor was predominantly solid with focal cystic degeneration. Histological examination showed an encapsulated spindle cell tumor with nuclear palisading, very focal nuclear atypia and widespread foam cell infiltration - findings consistent with ancient schwannoma. A diagnosis of ancient schwannoma can be considered for a solid-cystic encapsulated mass in the retroperitoneum. Malignant transformation is very rare. Local recurrence is uncommon following complete excision. The authors have nothing to disclose.