M esenteric ischemia can have a variety of presentations, ranging from classic and predictable to unusual and occult. For instance, a visceral vascular obstruction from a cardioembolic source tends to be acute and spares the proximal splanchnic vasculature. In contrast, when atherosclerotic disease develops at the origins of the aortic branches, it is typically preceded by chronic symptoms.1,2 Usually, the redundancy of the vascular collaterals between the fore-and midgut, which involves structures such as the pancreaticoduodenal arcade and the arc of Buhler, provides protection against ischemia. However, patients with anatomic variations-such as a celiomesenteric trunk (CMT), in which the superior mesenteric artery (SMA) originates from the celiac axis (CA) (Fig. 1)-lack this protection. In these patients, successful diagnosis and management depends on astute interpretation of radiologic images (usually computed tomographic angiograms [CTAs]).3,4 Misdiagnosis can lead to prolonged suffering or death.We present the cases of 2 patients with symptoms of mesenteric ischemia in whom we diagnosed CMT. Their cases illustrate the different courses of disease and outcomes in this population. Case Reports Patient 1Chronic Mesenteric Ischemia. A 57-year-old woman presented with a 5-year history of severe, postprandial abdominal pain that had led to a fear of eating and a 40-lb weight loss. Over the years before admission, she had undergone endoscopic and ultrasonographic evaluations with unremarkable results. Additionally, she had undergone prolonged empiric treatment for peptic ulcer disease, which was unsuccessful in controlling her symptoms. She had been referred to our clinic after an outpatient CTA revealed no ventral branch in the anticipated location on the SMA, occlusion of the proximal CA, and a CMT (Fig. 2A). The inferior mesenteric artery (IMA) was enlarged (6 mm), as was a tortuous marginal arcade (up to 7.5 mm) (Fig. 2B). Elective surgical exploration confirmed the presence of CMT and revealed compression of the origin of the celiac trunk by the median arcuate ligament (MAL). There were also chronic fibrotic changes in the CMT. Even after lysis of the crural fibers, the CMT remained occluded, and Doppler ultrasound testing of the structure produced poor signals. Therefore, we performed an aortomesenteric bypass with a 6-mm Dacron graft to the confluence of branches originating from the CMT. Exploration of the remainder of the abdomen confirmed a markedly hypertrophic marginal arcade and its Case Reports