We present the case of a 59-year-old male who presented with sudden onset of severe epigastric pain and laboratory studies consistent with acute pancreatitis. Imaging showed a dramatic interval increase in mesenteric edema with a normal pancreas, and a diagnosis of acute-onset sclerosing mesenteritis was made. Corticosteroids were initiated, and the patient demonstrated a dramatic improvement in symptoms and laboratory abnormalities overnight. Subsequent imaging after 4 and 8 months revealed continued improvement of mesenteric abnormalities consistent with consolidative sclerosing mesenteritis with a radiographic picture more typical of this unusual disorder. The abrupt onset of symptoms with acute dramatic development of mesenteric edema and dramatic resolution of symptoms has not been previously described. © 2014 Springer.