Panniculitis of the Lower Extremities Caused by Acute Deterioration of Autoimmune Pancreatitis.

A 73-year-old female with type 1 autoimmune pancreatitis (AIP) presented with painful erythema on her lower extremities and elevated serum pancreatic enzyme levels. Her CT images revealed focal enlargement of the pancreatic tail with an increased density of the surrounding fatty tissue. Based on serum and CT findings, she was diagnosed as having acute deterioration of AIP. Skin biopsy of erythema revealed fat necrosis with ghost cells, calcification, and inflammatory infiltration, consistent with pancreatic panniculitis. Increasing the prednisolone dose to 25 mg/day promptly ameliorated her symptoms and normalized her enzyme levels. Pancreatic panniculitis is a rare complication of pancreatitis characterized by painful subcutaneous nodules and fat necrosis. Although it has been reported in association with conditions such as pancreatic cancer and chronic pancreatitis, its occurrence in AIP has not been documented. This case highlights pancreatic panniculitis as a potential complication of AIP for the first time.