Retroperitoneal GIST: An exceptional location of a rare tumour. A case report from Ouagadougou and review of the literature.

Abstract

IntroductionGIST can occur in all segments of the gastrointestinal tract with a predilection for the stomach. Retroperitoneal localization remains exceptional. We report a case to describe our diagnostic and therapeutic approach.Case presentationA 55-year-old patient was admitted with borborygms and a sensation of lumbar swelling for 6 months. He was diabetic and hypertensive. The clinical examination noted a right lumbar mass with perception of bowel sound anterior to the mass, with minimal discomfort and mobility. Ultrasound revealed a hypervascularised, encapsulated, well-limited retroperitoneal tissue mass in contact with the right psoas muscle. Abdomino-pelvic CT scan showed a large, hypervascularized, encapsulated, calcified tissue mass measuring 147 × 106 mm in close contact with the outer edge of the right psoas muscle, suspected of being malignant. MRI noted a suspicious process developed at the expense of the right psoas muscle in its lumbar and iliac portion suggestive of a psoas rhabdomyosarcoma. The patient underwent laparotomy with a retroperitoneal approach by lumbar incision. Histology and immunohistochemistry revealed a GIST expressing CD117. The patient was put on imatinib for 6 months. He is complaint-free after 4 months.DiscussionDespite the rarity of retroperitoneal GIST, it should be considered in the presence of any retroperitoneal mass. This will allow for early management.ConclusionRetroperitoneum is an exceptional location for GIST. Surgery remains the mainstay of curative treatment. Adjuvant imatinib reduces the risk of recurrence. The prognosis is usually good.