Panniculitis is not one simple medical disorder but a group of diseases whose typical feature is presence of inflammation in the adipose tissue located subcutaneously.
The presentation of a patient with panniculitis depends on the type of disorder. In general most patients will complain of tender subcutaneous nodules. Other common complaints include fever, weight loss, general malaise and fatigue . On physical exam, one may see the following features:
- Generalized swelling of the body, especially the extremities
- Multiple nodules in the subcutaneous tissues that are tender to deep palpation
- Discoloration of skin. The skin and subcutaneous tissues may feel woody and irregular to touch. In patients in whom the condition has subsided, depression in skin may be seen due to lipolysis and dissolution of fat.
Entire Body System
She complained of edema of her lower legs and face, general fatigue, and dyspnea. She was overweight and had type 2 diabetes (T2D). [ncbi.nlm.nih.gov]
Symptoms include tender skin nodules, and systemic signs such as weight loss and fatigue. [en.wikipedia.org]
After several months, she again described generalized fatigue associated with tender cervical lymphadenopathy. A CT scan revealed enlarged bilateral jugular digastric lymphadenopathy. [jco.ascopubs.org]
You might also have body-wide symptoms, such as: fatigue fever 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. [healthline.com]
JAMA Oncol. 2015;1(5):684-686. doi:10.1001/jamaoncol.2015.0457 Ibrutinib is an oral inhibitor of Bruton tyrosine kinase (BTK) with marked activity in several B-cell malignant neoplasms. 1 Commonly reported adverse events include diarrhea, infection, fatigue [jamanetwork.com]
- Wound Infection
A wound infection with Enterococcus faecium was treated with antibiotic therapy (carbapenem for seven days) and local therapy. At 6-week follow up the wound showed good granulation tissue and was healing well by secondary intention. [ncbi.nlm.nih.gov]
Simultaneously, she was diagnosed as having advanced pancreatic cancer; and a distal pancreatectomy and splenectomy were performed. [ncbi.nlm.nih.gov]
- Recurrent Infection
Panniculitis occurred before the age of 2 years in the 4 patients and preceded the onset of recurrent infections because of immunodeficiency in 2. [ncbi.nlm.nih.gov]
Panniculitis is diagnosed based on a combination of clinical features and results of culture . A biopsy is always required to confirm the diagnosis of panniculitis. The biopsy is usually done with a longer needle and tissue is required. An aspiration biopsy is not adequate to make the diagnosis. Patients need to be booked for surgery and a formal biopsy should be done in the operating room. A small skin incision should be made and adequate subcutaneous tissue should be obtained. Fat must be present in the tissue specimen. Imaging studies may be required depending on the cause. Cultures and work up for malignancy and collagen vascular disorders may be required depending on patient presentation.
The management of panniculitis depends on the cause. A thorough effort must be made to search for the cause and treat it. If the cause is an infection, then one may need to use antibiotics. All other offending medications must be discontinued.
If the extremity is affected, elevation and rest may help reduce swelling and pain. In many individuals with panniculitis, the extremity may be chronically swollen and use of compression stocking may be of benefit. Unfortunately because of the pain, compliance with stockings is reduced.
The pain in panniculitis can be mild to moderate. Most patients benefit from use of non-steroidal anti-inflammatory agents (NSAIDs) like ibuprofen, aspirin or indomethacin.
To reduce inflammation which is not from an infectious case, systemic steroids may be used. Initially patients are prescribed oral steroids but in acute cases, IV steroids for 24-48 hours may help relieve the symptoms. Those patients who fail to respond to steroids or have signs of an infection may benefit from the use of antibiotics like tetracycline. In chronic recalcitrant cases, hydroxychloroquinine may help.
There is some literature that supports use of potassium iodide tincture for tender nodules, but this is not a universal finding.
The role of surgery for the treatment of panniculitis is minimal. Surgery is only done to obtain a specimen in cases of visceral and deep lesions. In some patients with isolated lesions or nodules of the subcutaneous tissues that are painful or are compressing a critical structure, surgery may be required. Surgery is also performed for necrotic lesions or when there is definitive evidence of an abscess.
The prognosis of patients with panniculitis depends on the cause. In cases caused by medications or toxins, the prognosis is good as the disorder reverses once the offending agent is removed. However, panniculitis associated with a systemic disorder like systemic lupus erythematosus or a malignancy has a poor prognosis.
The disorder may be classified by absence of presence of systemic symptoms or by cause. Classification by causes include the following:
- Environmental: Cold exposure
- Collagen vascular disease: Systemic lupus erythematosus, scleroderma
- Connective tissue disease: Sarcoidosis
- Drugs: Post steroids 
- Hereditary: Alpha-1-antitrypsin deficiency
- Endocrine: Pancreatitis, necrobiosis lipoidica
- Infectious: Leprosy, tuberculosis, HIV 
- Inflammatory bowel disease: Crohn disease
- Malignancy: Lymphoma, histiocytosis, pancreatic cancer 
- Post radiation
- Rheumatological: Gout, crystal associated
- Toxins: Bromides
- Vasculitis: Leukocytoclastic vasculitis, superficial thrombophlebitis, cutaneous polyarteritis nodosa
The exact number of people who develop panniculitis is unknown. The disorder is rare and often there is a long delay before diagnosis is made. Panniculitis can occur in both genders and in people of all ages. It appears that certain forms of panniculitis are more common in women. To date, epidemiology has lagged because there are only isolated case reports published.
Over the years, panniculitis has been histologically classified based on the location of inflammatory cells within the fatty tissue. The inflammatory cells may aggregate within the fatty lobules or in the septa which separate them. In addition, the classification also depends on the presence or absence of any vasculitis. The current classification has four main histological subtypes which include the following:
- Lobar panniculitis without vasculitis
- Lobar panniculitis with vasculitis
- Septal panniculitis without vasculitis
- Septal panniculitis with vasculitis
Panniculitis can also be classified the following way:
Mostly lobular panniculitis which may be caused by:
- Erythema induratum of Bazin, or Bazin disease, is a panniculitis that predominantly occurs at the back of the calves. The disorder is typically bilateral. Even though over the years the disorder has been linked to several microorganisms including tuberculum bacillus, to date no organism has ever been isolated.
- Septal panniculitis may also be a feature of alpha-1-antitrypsin deficiency .
- Cold panniculitis that occurs after exposure to cold. This disorder is often seen in young children who suck on popsicles or ice cubes. It usually presents with tender nodules around the cheeks and disappears spontaneously.
- Chronic venous insufficiency
- Poststeroid panniculitis
- The collagen vascular disorder, systemic lupus erythematosus is also associated with painful panniculitis that is often seen in women.
- Pancreatic panniculitis results when there is extensive release of pancreatic enzymes resulting in fat necrosis. Subcutaneous fat necrosis may also be seen in patients with pancreatic cancer.
- Subcutaneous fat necrosis of the newborn is a type of panniculitis seen in newborn and resolves spontaneously. It is thought that this type of panniculitis is due to hypoxic injury suffered at birth.
- Gouty panniculitis
- Traumatic panniculitis
- Factitious panniculitis
Mostly septal panniculitis which may be caused by:
- Erythema nodosum is the most common mostly septal panniculitis. The disorder has been associated with inflammatory bowel disease, hepatitis C, tuberculosis, pregnancy, medications (sulfonamides) and certain malignancies like non-Hodgkin lymphoma and pancreatic cancer .
- Leukocytoclastic vasculitis
- Superficial thrombophlebitis
- Cutaneous polyarteritis nodosa
- Necrobiosis lipoidica
- Subcutaneous granuloma annulare
Because the cause of panniculitis is not always known, it is not possible to prevent the disorder. However, all patients should be educated that if they develop long standing tender nodules under the skin, they should seek help from a healthcare professions. The earlier the diagnosis is made, the better the prognosis. It is important for patients not to smoke or take medications when not needed. Children should avoid popsicles if they have one episode of cold induced panniculitis.
Panniculitis is a syndrome of several medical disorders which have one characteristic clinical feature, inflammation in the adipose tissue located beneath the skin. It is important to note that inflammatory disorders that involve the overlying dermis or fascia are not considered panniculitis. For panniculitis to be present the inflammatory reaction must be present in the fatty tissues. Even though there are many conditions that can cause inflammation of fat in the subcutaneous tissues, the majority of cases have very similar clinical features such as pain, tender nodules, fever, weight loss and general malaise  .
Panniculitis can occur in any part of the body and in some cases the inflammatory fatty nodules may develop underneath the skin and in other individuals this may occur around visceral organs. The diagnosis of panniculitis is only made after a deep skin biopsy and asking the pathologist to look at the histopathologic changes.
Panniculitis is a very challenging disorder because of the vague signs and symptoms. In the majority of cases, there is a long delay before the diagnosis is made.
Panniculitis is an inflammation of the fatty layer under the skin due to many possible causes. Patients should be educated on the symptoms of panniculitis such as fever, weight loss, pain and tender nodules. If the tender nodules persist despite treatment, they should seek help from a healthcare provider. Further, patients should avoid contact with other people with tuberculosis or other common infections. Patients should remain compliant with their medications and complete the course of antibiotic prescribed. If hydroxychloroquinine is prescribed patient should be told to watch out for visual problems, and see a doctor as soon as possible if there is a problem.
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