Looking beyond lymph nodes: Beware of the lurking pseudoaneurysm!

An arteriovenous fistula of the superior mesenteric vessels leading to pseudoaneurysm formation is rare and most commonly occurs after blunt trauma or surgery. We describe a case of a superior mesenteric artery–superior mesenteric vein (SMA/SMV) pseudoaneurysm that was initially misinterpreted as an enlarging hypervascular nodal metastasis on surveillance computed tomography (CT) in a patient who had undergone ileal carcinoid resection. When the case was discussed at the specialist multidisciplinary meeting to consider surgical resection, it was noted that the apparent “hypervascular node” on CT had a signal void character on magnetic resonance imaging, which is atypical for a lymph node. Coronal CT reformat demonstrated a vascular origin from the superior mesenteric trunk. This resulted in the correct diagnosis of a pseudoaneurysm secondary to an SMA/SMV fistula. This avoided an unnecessary repeat surgery, and the patient underwent endovascular repair. In our patient, the distal was closed by 3-mm coils and the proximal was closed by an Amplatzer plug with successful results. Hence, it is crucial for radiologists to have a systematic approach and understanding of vascular-related abnormalities to avoid misdiagnosis that can potentially lead to unwanted morbidity.