The Diagnosis: Pancreatic Panniculitis
The biopsy specimen revealed necrosis of the panniculus with “ghost” cells (Figure). Calcification was encountered. Changes of vasculitis were not identified and fungal organisms were not noted. The histopathologic findings supported a diagnosis of pancreatic panniculitis.
Punch biopsy revealed necrosis of the panniculus with “ghost” cells, and calcification was encountered (H&E, original magnification ×20).
Pancreatic panniculitis has been associated with pancreatitis, pancreatic carcinoma, pancreatic pseudocysts, congenital abnormalities of the pancreas, and drug-induced pancreatitis.1 Skin lesions may herald a diagnosis of pancreatic disease in an outpatient and should prompt thorough clinical evaluation when encountered in an outpatient setting. Our patient first developed tender nodules on the left shin 2 to 3 weeks prior to presentation. She reported that her initial nodules were flesh colored but then became erythematous and tender over 1 week’s time. The patient’s history was remarkable for ovarian cancer. She had been hospitalized 2 weeks prior to presentation for abdominal pain and ascites. Imaging studies revealed a cystic lesion in the head of the pancreas. The pancreas was traumatized during a peritoneal tap. Her nodules developed shortly thereafter and were distributed on the arms, legs, back, and abdomen.
Pancreatic tumors or inflammation are thought to trigger pancreatic panniculitis by releasing enzymes. Pancreatic enzymes such as lipase are thought to play a role in the development of pancreatic panniculitis by entering the vascular system and leading to fat necrosis.2,3 Biopsy reveals necrosis of adipocytes in the center of fat lobules.4 Ghost cells result from hydrolytic activity of enzymes on the fat cells followed by calcium deposition. A report indicates that fungal infection or gout also can cause changes that mimic pancreatic panniculitis.5
Other entities in the differential diagnosis can be excluded by biopsy. Polyarteritis nodosa is a vasculitis. Although panniculitis may be seen in polyarteritis as a secondary phenomenon, lesions are centered around blood vessels and often eventuate in ulceration.6 Subcutaneous fungal infection typically reveals organisms on periodic acid–Schiff stain.7 Pyoderma gangrenosum is associated with ulceration and a neutrophilic infiltrate that is often centered around a central pilosebaceous unit in developing lesions.8 Erythema nodosum is a panniculitis in which septal inflammation predominates.9 These differential diagnoses of pancreatic panniculitis are summarized in the Table.
Pancreatic panniculitis can be associated with acute arthritis and inflammation of periarticular fat.10 Treatment of pancreatic panniculitis is usually focused on the underlying pancreatic disease.11,12 Our patient benefited from analgesic therapy and her lesions improved on follow-up. Clinicians encountering a patient with new tender nodules should be prompted to perform a biopsy. When histopathologic evaluation reveals ghosted adipocytes, pancreatic panniculitis should be suspected and clinical evaluation undertaken.