Idiopathic myointimal hyperplasia of mesenteric veins mimicking steroid-refractory ulcerative colitis: A case report

Figure 5 Histopathologic findings of the resected colon consistent with idiopathic myointimal hyperplasia of mesenteric veins. A: A mesenteric artery showing a preserved normal wall architecture without intimal thickening (white arrow), × 100; B: A mesenteric vein demonstrating marked myointimal hyperplasia with near-complete luminal obliteration (orange arrows), × 100; C: Small venules exhibiting subendothelial fibrin deposition, seen as eosinophilic material beneath the endothelium (arrowhead), × 40. These findings are characteristic of idiopathic myointimal hyperplasia of mesenteric veins, highlighting selective venous involvement with arterial sparing.