#LancetClinicalCase: Arthritis with nodular skin lesions
A rheumatology consult was taken for a 22-year-old man admitted with acute pancreatitis who developed nodular skin lesions over both shins and joint pains in the ankles, knees, and wrists. The patient had a history of mild dull aching, epigastric pain for 1 year; and presented with fever for 1 month with dyspnoea. In the hospital, blood tests showed raised amylase (1997 units per L) and lipase (889 units per L).

MRI of the abdomen (figure 1A) showed diffuse enlargement of the pancreas with mild peripancreatic fat stranding and dilated main and peripheral ducts. Percutaneous drainage of the peripancreatic fluid collection was done. 2 days later he developed non-pruritic nodular erythematosus lesions over both shins and synovitis of the knees, ankles, and wrists. Skin biopsy from the nodular swellings revealed panniculitis (figure 1B). Synovial fluid aspiration showed thick white pus-like fluid, with a high neutrophil count but sterile on culture. Radiography of both ankles and feet showed multiple lytic lesions (figure 1C) and contrast-enhanced MRI of ankles showed multiple areas of altered signal intensity in multiple bones of both ankles and feet with mild joint effusion and synovitis of multiple joints of the feet (figure 1C). The patient was diagnosed as having pancreatitis panniculitis and polyarthritis syndrome. The areas of altered signal intensity on MRI of the ankle and foot were consistent with fat necrosis (figure 1D).

Endoscopic retrograde cholangiopancreatography revealed pancreatic duct disruption in the head of the pancreas with opacification of upstream main pancreatic duct and tortuous course. A stent was placed in the duct across the leak to bridge the disruption. Joint pain was managed with non-steroidal anti-inflammatory drugs (NSAIDs) and intra-articular methylprednisolone in the ankle joints. The patient's symptoms improved and only mild ankle synovitis remained after 1 month. In the absence of any identifiable cause, the disease was considered to be idiopathic chronic calcific pancreatitis (calcification on contrast-enhanced CT images).