Pancreatic panniculitis.

Pancreatic panniculitis (PP) is a rare variant of panniculitis characterized by subcutaneous fat necrosis, that affects 0.3-3% of patients across a range of different pancreatic disorders. It presents with painful, tender, erythematous to violaceous nodules that may undergo spontaneous ulceration and discharge of an oily brown, viscous material, resulting from liquefactive necrosis of adipocytes. These lesions usually involve the lower extremities, although may also spread over the buttocks, trunk, arms and scalp. In addition to the skin, fat necrosis may involve periarticular, abdominal and intramedullary adipose tissue. In 40% of cases, skin manifestations can precede by 1 to 7 months the abdominal symptoms of pancreatic disease, which include mostly acute and chronic pancreatitis, pancreatic carcinoma, more frequently of acinar cell type, and pancreatic abnormalities. Histopathologically, PP shows characteristic features of mostly lobular panniculitis with marked necrosis of adipocytes. The necrotic adipocytes with finely granular and basophilic material in the cytoplasm due to calcium deposits are known as "ghost adipocytes". The treatment of pancreatic panniculitis is directed to the underlying pancreatic disease. The prognosis is poor in cases associated with pancreatic carcinoma. When there is widespread and persistent disease, frequent relapses, or ulceration, the possibility of an occult carcinoma of the pancreas should be always considered. While describing three patients seen at the Dermatology Section of the University of Genova from 1990 to 2012, we highlight that, in addition to the rarity of the disease, the precise diagnosis requires adequate samples consisting in large-scalpel incisional biopsies of fully developed lesions.