Red painful nodules in a hospitalized patient

Diagnosis: Pancreatic panniculitis

Pancreatic panniculitis, or enzymatic panniculitis, is a rare necrotizing subcutaneous inflammatory process that occurs in 2% to 3% of cases of pancreatic disease.¹ It is associated with acute and chronic pancreatitis, pancreatic carcinoma (typically pancreatic acinar type), and less commonly, with pancreatic anomalies such as pancreatic divisum.^1,2

It’s theorized that the systemic release of trypsin from pancreatic cell destruction causes increased capillary permeability and subsequent escape of lipase from the circulation into the subcutaneous fat. This causes fat necrosis, saponification, and inflammation.^3,4 Pancreatic panniculitis is demonstrated histologically as hollowed-out adipocytes with granular basophilic cytoplasm and displaced or absent nuclei—aptly named “ghostlike” adipocytes.^3-6

Painful, erythematous nodules most commonly present on the distal lower extremities. Nodules may be found over the shins, posterior calves, and periarticular skin. Rarely, nodules may occur on the buttocks, abdomen, or intramedullary bone.⁷ In severe cases, nodules spontaneously may ulcerate and drain an oily brown, viscous material formed from necrotic adipocytes.¹

Timing of the eruption of skin lesions is varied and may even precede abdominal pain. Lesions can involute and regress several weeks after the underlying etiology improves. With pancreatic carcinoma, there is a greater likelihood of persistence, atypical locations of involvement, ulcerations, and recurrences.⁷

The histologic features of pancreatic panniculitis and the assessment of the subcutaneous fat are paramount in diagnosis. A deep punch biopsy or incisional biopsy is necessary to reliably reach the depth of the subcutaneous tissue. In our patient, a deep punch biopsy from the lateral calf was performed at the suggestion of Dermatology, and histopathology revealed necrosis of fat lobules with calcium soap around necrotic lipocytes, consistent with pancreatic panniculitis (FIGURE 3).

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