Idiopathic nodular panniculitis
What is panniculitis?
Panniculitis is a condition where the fat under the skin becomes inflamed.
What is nodular panniculitis?
Nodular panniculitis is characterised by one or multiple, recurrent, subcutaneous nodules. These commonly arise on the legs. Nodular panniculitis is associated with acute systemic symptoms such as fever, general malaise and abdominal pain.
Nodular panniculitis is also referred to as lobular panniculitis, and relapsing, febrile, non-suppurative panniculitis. In the past, it was also called Weber Christian disease.
Who gets nodular panniculitis?
Nodular panniculitis is rare. It occurs in males and females of all age. It is most commonly seen in young adult women, and it rarely affects young children.
Nodular panniculitis is associated with autoimmune diseases such as Sjogren syndrome, inflammatory bowel disease, systemic lupus erythematosus, diabetes mellitus and alpha-1-antitrypsin deficiency disease.
What causes nodular panniculitis?
The cause of nodular panniculitis is unknown. One hypothesis is that fat may trigger an autoimmune or autoinflammatory granulomatous reaction.
The mechanism of nodular panniculitis is that white blood cells infiltrate and damage the subcutaneous fat, causing necrosis and fibrosis.
What are the clinical features of nodular panniculitis?
The first signs of nodular panniculitis are
- Painful nodules, 1–2 cm in diameter, on both thighs, legs and buttocks
Each nodule regresses after a few weeks. In some cases, the nodules can ulcerate and leak an oily, yellow discharge.
Complications of nodular panniculitis
Nodular panniculitis can involve visceral organs and cause other symptoms and complications such as:
- Polyarthralgia (sore joints) and polymyalgia (sore muscles)
- Bowel perforation
- Pleural effusion
- Anaemia from bone marrow infiltration
How is nodular panniculitis diagnosed?
Nodular panniculitis is diagnosed by its clinical features. Other forms of panniculitis should be excluded. Skin biopsy shows inflamed adipocytes (fat cells).
What is the treatment for nodular panniculitis?
There is no one effective therapy. Nodular panniculitis without involvement of other organs should be treated symptomatically.
- Analgesics such as nonsteroidal anti-inflammatory drugs should be prescribed for pain
- Dressings should be applied if there are ulcers.
- Systemic corticosteroids such as oral prednisone may be effective in severe nodular panniculitis. The dosage should be tapered after 7–10 days over a period of 4–6 weeks.
Other treatments reported to be of benefit include mycophenolate mofetil, thalidomide, clofazimine, anti-malarials such as hydroxychloroquine, antibiotics, dapsone, and immunosuppressive drugs such as azathioprine and ciclosporin.
What is the outlook for nodular panniculitis?
Nodular panniculitis tends to settle down after a few weeks or months. There may be a single episode, or the disease may relapse repeatedly over time.
Involvement of other organs is associated with a high risk of mortality.