What is Panniculitis?

Panniculitis is a general term for the inflammation of the layer of fat, the panniculus adiposus, under the skin. An affected person would go to the doctor because of painful skin masses and nonspecific symptoms, such as fatigue and weight loss. Treatment of this condition depends on the identified cause.

The panniculus adiposus is located external to the panniculus carnosus, a thin layer of muscles. Various disorders can cause an inflamed panniculus adiposus, but they have similar panniculitis symptoms. An affected person usually feels that his or her skin is thick and wood-like. This sensation is frequently accompanied with a reddish or dark discoloration, together with tenderness.

A deep skin biopsy of the tender mass is needed for its diagnosis. Once panniculitis is confirmed, the doctor tries to identify the cause. Additional symptoms such as fever, pain, arthritis, and preexisting conditions, all provide a clue on the cause.

Causes of panniculitis include systemic diseases and localized diseases. Localized diseases are usually limited in location, and do not involve other areas of the body. Lipodermatosclerosis is one of the localized soft tissue disorders that have panniculus inflammation as a major feature. Only the lower extremities are affected by this condition, and patients have painful legs that look like inverted soda bottles and may have reddish-brown color. Most of the time, this condition is secondary to venous insufficiency and/or obesity.

Systemic diseases are disorders that involve the whole body. These disorders include systemic lupus erythematosus and scleroderma. Lymphomas and pancreatic cancer may also result in the inflammation of subcutaneous fat.

Erythema nodosum is a common form of panniculitis wherein the body’s reaction to immune challenges such as infections, medications, pregnancy, and cancer, leads to skin manifestations. Infections that can cause erythema nodosum include streptococcus, tuberculosis, and leprosy, and drugs that can cause this disorder include sulfonamides, such as co-trimoxazole and oral contraceptive pills. Erythema nodosum initially manifests on the anterior leg or shins as red and tender nodules with irregular borders during the first week. On the second week, these nodules assume a bluish color, followed by a yellowish hue. As the overlying skin desquamates or sheds off within one to two weeks, the nodules eventually disappear.

Once the doctor has identified the cause of panniculitis, appropriate treatment is initiated. For instance, some cases of erythema nodosum may require stopping the intake of a specific drug or administration of a certain antibiotic. In the case of connective tissue disorders, such as lupus erythematosus, steroids may be given to suppress the immune system. Anti-inflammatory and analgesic treatment, such as ibuprofen, celecoxib, and diclofenac, may be warranted in other cases.