[Benign schwannoma, a rare retroperitoneal tumour].

Primary retroperitoneal tumours are rare in adults. Among retroperitoneal tumours derived from nervous tissue, schwannoma is defined as a tumour arising from neurilemma or Schwann nerve sheath cells. It is a very rare tumour, especially in the retroperitoneal site (0.2%). Its diagnosis is immunohistological, and treatment is surgical, consisting of complete resection of the mass due to the risk of malignant degeneration. The authors report the case of a 38-year-old patient admitted with isolated right lumbar pain. Imaging (ultrasound and CT urography) revealed a retroperitoneal tumour measuring 6 x 9 cm. Resection was performed by right thoraco-pleuro-laparatomy. The immunological and histological study concluded on benign schwannoma. With a postoperative follow-up of two years, the patient has not presented any recurrence of this retroperitoneal schwannoma.