Panniculitis

Definition, Etiology, PathogenesisTop

Panniculitis is an inflammatory reaction caused by necrosis of adipocytes. It mainly involves the subcutaneous tissue but may affect adipose tissue anywhere in the body and may also involve a number of systems and organs. Etiology is unknown. Triggering factors include trauma (including self-inflicted injury), external exposure to chemicals, biochemical disturbances (eg, increased activity of pancreatic enzymes), and infections. Panniculitis may be accompanied by other systemic connective tissue diseases (systemic lupus erythematosus), lymphoproliferative neoplasms, or histiocytosis.

Clinical Features and Natural HistoryTop

The most common type of panniculitis is idiopathic neutrophilic lobular panniculitis (Weber-Christian disease). It usually occurs in White women. The key manifestations are very painful nodular lesions in the subcutaneous tissue, usually located on the limbs and less often on the trunk. An episode of the disease is commonly preceded by joint and muscle pain and low-grade fever. Subcutaneous lesions persist for several weeks and heal, leaving round, depressed scars. Less frequently, fistulae form with a sterile, oily discharge. Occasionally, arthritis, serositis, and nephritis occur, as well as liver and bone marrow injury. Subcutaneous lesions may coexist with pancreatic disorders (pancreatitis, pseudocyst, posttraumatic injury, ischemia). In some cases they are accompanied by arthritis, thus giving rise to a triad of symptoms: panniculitis, arthritis, pancreatitis.

DiagnosisTop

Diagnostic Tests

1. Laboratory tests: In patients with an acute episode of panniculitis tests reveal a marked elevation in the erythrocyte sedimentation rate, leukocytosis with neutrophilia, anemia, occasionally proteinuria and increased red blood cell and white blood cell counts in urinary sediment, and elevated serum lipase levels (in patients with pancreatic involvement).

2. Histologic analysis of biopsy specimens collected from inflammatory lesions early in the course of the disease reveals necrosis of adipocytes, presence of macrophages containing phagocytosed lipids, thrombotic changes in vessels, and fibrosis at later stages.

3. Radiographs of the affected joints reveal joint space narrowing and osteolytic lesions.

Diagnostic Criteria

Diagnosis is based on typical histologic findings of lobular panniculitis. It is important to establish whether any other pathology apart from subcutaneous lesions is present that may be related to panniculitis (eg, panniculitis may be the presenting feature of pancreatic disease) and whether the disease is idiopathic or is part of another condition. Exclude intentional skin self-inflicted injury in patients with psychiatric disorders.

Differential Diagnosis

Erythema nodosum, subcutaneous tissue infection.

TreatmentTop

Idiopathic panniculitis may be treated with nonsteroidal anti-inflammatory drugs. In severe episodes of the disease glucocorticoids or other immunosuppressive agents (cyclosporine [INN ciclosporin], cyclophosphamide) may be used.