Panniculopathy

Panniculopathy is a broad term for disorders that affect the subcutaneous adipose tissue, collectively described as panniculitis when inflammation is present. It encompasses inflammatory, necrotizing, and lipodystrophic conditions of the subcutaneous fat and can be localized or widespread. Pathologically, panniculitis is categorized by the primary location of inflammation: lobular panniculitis involves the fat lobules, while septal panniculitis involves the connective tissue septa between lobules; vasculitis may or may not be present.

Common forms include septal panniculitis such as erythema nodosum, which typically presents as tender nodules on the shins and is often linked to infections, medications, or systemic diseases. Lobular panniculitis includes erythema induratum (Bazini) and lupus panniculitis, among other infection- or immune-related processes. Additional conditions include pancreatitis-associated fat necrosis and various idiopathic lobular panniculitides.

Etiology is diverse, spanning infections, autoimmune and inflammatory diseases, medications, metabolic disturbances, and trauma. Identifying and addressing an underlying trigger is often a key part of management. Diagnosis relies on clinical evaluation supported by skin biopsy for histopathology; laboratory tests may help identify infections, autoimmune processes, or systemic conditions. Imaging is not typically diagnostic but may be used to assess associated complications.

Treatment focuses on addressing the underlying cause and controlling inflammation. Mild cases may improve with rest, leg elevation, and nonsteroidal anti-inflammatory drugs; more persistent or severe cases may require corticosteroids or immunosuppressants. The prognosis varies with the underlying etiology but panniculopathy can resolve, recur, or lead to chronic changes such as scarring and fat atrophy.