後腹腔動靜脈畸形表現為疑似胃腸道基質瘤復發：病例報告

劉順琳、張兆祥

中國醫藥大學附設醫院 泌尿部

Retroperitoneal Arteriovenous Malformation Mimicking Recurrent Gastrointestinal Stromal Tumor: A Diagnostic Challenge

Shun-Lin Liu, Chao-Hsiang Chang

Department of Urology, China Medical University Hospital, China Medical University, Taichung 404, Taiwan

Purpose:  Retroperitoneal tumors in patients with a history of gastrointestinal stromal tumor (GIST) often raise concern for recurrence or metastasis. However, benign lesions may present with similar radiological features, posing a diagnostic challenge. We report a rare case of retroperitoneal arteriovenous malformation (AVM) mimicking recurrent GIST.

Case: A 71-year-old woman with a history of incidentally discovered jejunal gastrointestinal stromal tumor (GIST, pT3N0M0) status post segmental resection was treated with Imatinib due to suspected residual disease in the left adrenal and right para-renal regions.

For the left adrenal lesion, endoscopic ultrasound-guided biopsy revealed an adrenal cortical neoplasm. Follow-up imaging demonstrated a slight decrease in the size of the left adrenal lesion; however, the right para-renal mass showed progressive enlargement. Magnetic resonance imaging revealed a lesion adjacent to the duodenum, inferior vena cava, and right kidney. Differential diagnoses included recurrent GIST, neurogenic tumor, or hemangioma. CT-guided biopsy was attempted but was unsuccessful due to technical difficulty.

Therefore, surgical exploration was arranged for diagnostic purposes. Intraoperatively, a highly vascular retroperitoneal tumor with dense adhesions to surrounding structures was identified. Considering the high risk of bleeding, en bloc resection was performed instead of biopsy. Histopathological examination revealed an arteriovenous malformation/hemangioma composed of thick-walled arterioles and cavernous vascular spaces, with no evidence of malignancy.

Given the absence of recurrent GIST, imatinib therapy was discontinued, and the patient was placed under active surveillance with scheduled follow-up imaging.

Conclusions: Retroperitoneal vascular lesions such as AVM can closely mimic recurrent or metastatic GIST in imaging studies, especially in patients with prior malignancy. This case highlights the importance of considering benign etiologies in differential diagnosis to avoid misdiagnosis and unnecessary systemic therapy.