Panniculitis is a group of conditions that cause painful bumps, or nodules, to form under your skin, often on your legs and feet. These bumps create inflammation in the fat layer under your skin.
This layer is called the panniculus, or subcutaneous fat layer. It’s the type of fat that provides insulation and helps regulate your body temperature.
There are many different types of panniculitis. Which type you have depends on what area of the fat cell the inflammation is in.
You’re more likely to get panniculitis if you have an infection, inflammatory disease, or connective tissue disorder. These conditions sometimes affect young or middle-aged women.
Keep reading to learn more.
Although there are many different types of panniculus, they all cause similar symptoms. The main symptom is painful or tender bumps called nodules that form in the layer of fat under your skin. The bumps vary in size.
You’ll most often find these bumps on your legs and feet. Sometimes they’ll appear on your face, arms, chest, abdomen, and buttocks. The skin over these bumps might become discolored.
The bumps are large and deep. The tissue around them may break down. This is called necrosis. An oily substance may drain from them when this happens.
You might also have body-wide symptoms, such as:
- general sick feeling (malaise)
- joint and muscle pain
- abdominal pain
- nausea and vomiting
- weight loss
- bulging of the eye
These symptoms can come and go. The lumps may fade after a few days and weeks but then come back months or years later. After the bumps fade, they can leave behind a groove, or indentation, in your skin.
Inflammation in your body can also damage organs such as your liver, pancreas, lungs, and bone marrow.
Doctors classify panniculitis based on which part of the fat layer under the skin is inflamed. Septal panniculitis affects the connective tissue around the fat. Lobular panniculitis affects fat lobules.
This condition can also affect different types of immune cells in your skin, including:
Most types of panniculitis have both septal and lobular inflammation. Some forms include inflamed blood vessels in the skin, called vasculitis.
More specific types of panniculitis include:
- Erythema nodosum: This is the most common form of panniculitis. It causes red, painful lumps to form on the front of your lower legs. It also causes more general symptoms like fever, headache, and eye problems.
- Cold panniculitis: This type affects areas of skin that have been exposed to extreme cold, such as can occur when spending time outdoors.
- Lipodermatosclerosis: This type is linked to vein problems and obesity. It often affects overweight women over 40.
- Erythema induratum: This form affects the calves of middle-aged women.
- Subcutaneous sarcoidosis: This type is caused by the disease sarcoidosis.
- Weber-Christian disease: This term is used to describe a form of the disease that often affects women in midlife. It causes bumps on the thighs and lower legs. It can also involve other organs.
Many different conditions cause panniculitis, including:
- infections from bacteria (such as tuberculosis and streptococcus), viruses, fungi, or parasites
- inflammatory diseases, such as Crohn’s disease or ulcerative colitis
- injuries, such as from intense exercise, exposure to very cold temperatures, or injections of medicine into the fat layer under your skin
- connective tissue disorders such as lupus, rheumatoid arthritis, and scleroderma
- medicines such as sulfonamide antibiotics, iodide, bromide, and large doses of corticosteroids
- sarcoidosis, which is a condition that causes clumps of inflammatory cells to form in your body
- cancers like leukemia and lymphoma
- pancreatic diseases
- alpha-1 antitrypsin deficiency, which is a genetic disorder that causes lung disease and liver disease
Sometimes panniculitis has no obvious cause. This is called idiopathic panniculitis.
To diagnose panniculitis, your doctor will examine your skin and ask about your medical history and symptoms. Your doctor will likely remove a small piece of your skin, which is called a biopsy.
The tissue sample will go to a lab to be checked under a microscope for inflammation and other signs of panniculitis.
Your doctor might also do one or more of these other tests to check for conditions that cause panniculitis:
- a throat swab to check for bacterial infection
- a blood test to check levels of the protein alpha-1 antitrypsin
- erythrocyte sedimentation rate blood test to look for inflammation in your body
- chest X-ray
- CT scan
The goal in treating panniculitis is to bring down inflammation and relieve your symptoms. Your doctor will first try to treat the condition that’s causing the inflammation. If a medicine caused your symptom, your doctor may tell you to stop taking it.
Medicines used to treat panniculitis include:
- nonsteroidal anti-inflammatory drugs such as aspirin (Bufferin) or ibuprofen (Advil) to bring down inflammation and relieve pain
- antibiotics, such as tetracycline, to treat an infection
- hydroxychloroquine, an antimalarial drug, to bring down inflammation
- potassium iodide to relieve symptoms
- steroid drugs taken by mouth or as an injection for a short period of time to bring down inflammation
Sometimes the bumps will heal on their own without treatment.
You can relieve the swelling and pain by:
- getting lots of rest
- elevating the affected body part
- wearing compression stockings
If treatments don’t relieve the bumps, surgery is an option to remove the affected areas of skin.
Your outlook depends on what caused the inflammation. Some conditions are easier to treat than others.
Panniculitis often comes and goes. The bumps may appear, stay for a few weeks, and then start to fade. Yet they can return in the future. Some forms of panniculitis leave permanent dents in the skin.
Your doctor is your best resource for information about your individual outlook.