Colonic schwannoma: A case of unusual presentation and outcome.

Background: Schwannomas are mesenchymal tumors arising from neural sheath cells and whose diagnosis is based on immunohistochemistery. The digestive and especially colonic location of this tumor is rare. Commonly described in elderly patient, their malignancy is unusual.

Case report: We report the case of a 23-year-old girl, with learning disability, operated in emergency for acute peritonitis. Peroperatively, we discovered a peritonitis secondary to a bulky perforated cecal tumor. We performed a right colectomy and an ileostomy. The posterior margin of the resection was macroscopically involved. The diagnosis of colonic schwannoma was confirmed with immunopathological examination of the surgical specimen. Surgical exploration 4 months later and morphological investigations during 2 years showed stability of the tumoral residue in the right iliac fossa. However, we noticed, on CT scanning control 2 years postoperatively, the appearance of a mesenteric recurrence. Exploratory laparotomy confirmed the unresectability of this mesenteric mass and showed the presence of multiple parietal nodules whose biopsies revealed their neurofibromatous nature. The 4 year follow-up of the patient didn't reveal any complication rather than need to right nephrostomy due to ureter compression by the primary tumoral residue.

Discussion: Colonic schwannoma is a rare disease, commonly described in uncomplicated stages. The learning disability of our patient had favorized the absence of declared symptoms and promoted the evolution of the cecal swhannoma until its perforation. This complication was not described before. Local recurrence has been also rarely reported in the literature. Association with neurofibroma may be hereditary in a context of neurofibromatosis or sporadic.

Conclusion: Colonic schwannoma may have polymorphic presentation mimicking malignant tumor in such cases. Not treated in time, it can lead to severe complications, such as tumoral perforation. Surgical resection remains the mainstay treatment. The slow evolutionary genius of schwannoma, even when incompletely resected by necessity, confirms its good prognosis.