Metastatic melanoma causing small intestinal perforation at the jejunojejunostomy after Roux-en-Y gastric bypass: a case report.

Background: Metastatic melanoma of the small intestine is relatively common, and among affected patients, the proportion with involvement of the small intestine ranges from 35% to 70%. Small intestinal perforation as a primary manifestation of metastatic melanoma is rare. We present the exceptional case of a perforation at the jejunojejunostomy after Roux-en-Y gastric bypass caused by metastatic melanoma.

Case Presentation: A 59-year-old woman with a history of a laparoscopic Roux-en-Y gastric bypass and toe amputation due to malignant melanoma (stadium IIIC) presented with an acute abdomen. The abdominal computed tomography scan showed a covered perforation at the jejunojejunostomy of the gastric bypass. The patient underwent an urgent surgical exploration revealing massive tumoral invasion of the anastomosis. The tumoral mass and anastomosis were resected and a new jejunojejunostomy was created. Histopathological examination identified the tumor as a malignant melanoma, so the current abdominal lesions were presumed to be metastases. The postoperative course was uneventful and adjuvant immunotherapy was started a week later. One year after surgery she was doing well with maintenance immunotherapy and there was no evidence of recurrent metastatic disease.

Conclusion: We report the first case of a perforation at the jejunojejunostomy after Roux-en-Y gastric bypass caused by metastatic melanoma. This exceptional case illustrates that a history of malignant melanoma in case of an acute abdomen should raise suspicion of possible metastatic disease.