(See also Erythema Nodosum Erythema Nodosum Erythema nodosum is a specific form of panniculitis characterized by tender, red or violet, palpable, subcutaneous nodules on the shins and occasionally other locations. It often occurs with... read more 
.)
Panniculitis can be classified as lobular or septal depending on the principal site of the inflammation within the fat.
Etiology of Panniculitis
There are multiple causes of panniculitis, including
Infections
Inflammatory disorders (eg, erythema nodosum Erythema Nodosum Erythema nodosum is a specific form of panniculitis characterized by tender, red or violet, palpable, subcutaneous nodules on the shins and occasionally other locations. It often occurs with... read more
, lipodermatosclerosis, polyarteritis nodosa Polyarteritis Nodosa (PAN) Polyarteritis nodosa is a systemic necrotizing vasculitis that typically affects medium-sized muscular arteries and occasionally affects small muscular arteries, resulting in secondary tissue... read more )Physical factors (eg, cold, trauma)
Lymphoproliferative disorders
Connective tissue disorders (eg, systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic, multisystem, inflammatory disorder of autoimmune etiology, occurring predominantly in young women. Common manifestations may include arthralgias and... read more
, systemic sclerosis Systemic Sclerosis Systemic sclerosis is a rare chronic disease of unknown cause characterized by diffuse fibrosis and vascular abnormalities in the skin, joints, and internal organs (especially the esophagus... read more 
)Pancreatic disorders
Symptoms and Signs of Panniculitis
Panniculitis is characterized by tender and erythematous subcutaneous nodules located over the extremities and sometimes over the posterior thorax, abdominal area, breasts, face, or buttocks. Rarely, nodules can involve the mesentery, lungs, scrotum, and cranium. Signs of systemic inflammation can accompany panniculitis.
Diagnosis of Panniculitis
Clinical evaluation
Excisional or incisional biopsy
Diagnosis of panniculitis is by usually by clinical appearance and can be confirmed by biopsy.
Treatment of Panniculitis
Supportive care
Anti-inflammatory drugs
Immunosuppressants
Any underlying causes of panniculitis are treated. There is no specific definitive treatment for panniculitis. Several strategies have been used with modest results, including nonsteroidal anti-inflammatory drugs, antimalarials, dapsone, and thalidomide.
Corticosteroids (1 to 2 mg/kg orally or IV once a day) and other immunosuppressive or chemotherapeutic drugs have been used to treat patients with progressive symptoms or signs of systemic involvement.
Key Points
Causes of panniculitis can vary widely.
Diagnose panniculitis by clinical evaluation (including presence of tender, red, subcutaneous nodules) and confirm with excisional or incisional biopsy.
Treat panniculitis supportively and consider anti-inflammatory or immunosuppressive drug therapy, particularly if manifestations are severe.
