Non-Neoplastic Dermatopathology

5.9

P ANCREATIC PANNICULITIS VS INFECTIOUS PANNICULITIS

Pancreatic Panniculitis

Infectious Panniculitis

Age

Middle-aged and elderly adults.

Any age.

Location

Lower extremities typically involved. May also extend to buttocks, trunk, upper extremities, and scalp. Systemically released pancreatic enzymes, such as amylase and lipase, cause necrosis of subcutaneous adipocytes and recruitment of neutrophilic inflammation. Most commonly associated with acute and chronic pancreatitis and pancreatic carcinoma. Tender, ill-defined, edematous, erythematous nodules that ulcerate and exude viscous, oily brown material. Often associated with arthralgias. Skin lesions may develop prior to diagnosis of pancreatic disease. 1. Lobular infiltrate with mixed inflammatory cells predominated by neutrophils (Fig. 5.9.2) . 2. Coagulative necrosis of adipocytes with saponification and “ghost” cells representing fat cell remnants (Figs. 5.9.1 , 5.9.3 , 5.9.4) . 3. Basophilic granular calcification (Figs. 5.9.1 and 5.9.3) . 4. Viable fat lobules with acute and chronic inflammation and lipophages. Elevated levels of amylase, lipase, and trypsin are usually present and aid in confirming the diagnosis. Eosinophilia is seen in a majority of cases.

Lower extremities often involved but also buttocks, abdomen, intertriginous regions, and upper extremities. Infection of the subcutaneous tissues from a wide variety of organisms including bacteria, fungi, mycobacteria, as well as protozoa and viruses. Infection can result from direct inoculation or spread through the bloodstream. Swelling and erythema often precede development of one or more fluctuant nodules that ulcerate. More commonly seen in individuals with diabetes mellitus or immunosuppression. 1. Epidermal acanthosis and parakeratosis. 2. Dermal edema with diffuse neutrophilic infiltrate. 3. Mixed septal and lobular inflammation with neutrophils predominating (Figs. 5.9.5 and 5.9.6) . Granulomas may be seen especially with fungal and mycobacterial causes (Fig. 5.9.7) . 4. Vascular proliferation with hemorrhage (Fig. 5.9.5) . 5. Fat necrosis may be present but generally no coagulative necrosis or saponification. Tissue Gram, PAS or GMS, and AFB or Fite stains to identify bacteria, fungi, and mycobacteria, respectively (Fig. 5.9.8) . Microbiologic culture to increase sensitivity of detection of organisms. Systemic antibiotics are generally necessary to clear infection. Surgical excision and/or debridement may be an option for isolated lesions.

Etiology

Presentation

Histology

Special studies

Treatment

Primarily supportive and directed toward treatment of underlying pancreatic disease.

Dependent upon organism, extent of infection, and comorbidities. Some fungal and mycobacterial infections may be difficult to clear and require long duration of antimicrobial therapy. Copyright © Wolters Kluwer, Inc. Unauthorized reproduction of the content is prohibited. 2023

Prognosis

Dependent upon associated pancreatic disease. Panniculitis usually resolves with clearing of pancreatic inflammation in cases associated with pancreatitis. Individuals with pancreatic carcinoma have a more prolonged course and high mortality rate. The triad of pancreatitis, arthralgias, and peripheral eosinophilia is associated with a poor prognosis.

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