Erythema nodosum in Adult
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SynopsisErythema nodosum (EN) represents the most common type of septal panniculitis (inflammation of the subcutaneous fat). It represents a form of hypersensitivity reaction precipitated by infection, pregnancy, medications, connective tissue disease, or malignancy. Streptococcal infections are the most common etiologic factor in children. Sarcoidosis, inflammatory bowel disease (see Crohn disease, ulcerative colitis), and medications (particularly oral contraceptive pills) are more commonly implicated in adults. Often a cause or trigger is never found.
Associated bacterial, viral, fungal, and protozoal infections are numerous and include Streptococcus, Shigella, Yersinia, Histoplasma, Coccidioides, HIV, Giardia, and COVID-19. Tuberculosis (TB) remains an important cause in areas of endemic disease. Less commonly, Campylobacter, Salmonella, cat-scratch disease, Chlamydia, syphilis, pertussis, leprosy, hepatitis B, blastomycosis, and sporotrichosis may be precipitants. Inflammatory associations include sarcoidosis, inflammatory bowel disease, Sjögren syndrome, reactive arthritis, and Behçet disease. In Crohn disease, EN may occur even if the Crohn disease is well controlled. Malignancy, such as lymphoma or leukemia, is a rare cause of EN.
The eruption typically persists for 3-6 weeks and spontaneously regresses without scarring or atrophy. Recurrences are sometimes seen, especially with reoccurrence of the precipitating factor(s).
Arthralgias, often in the ankles and knees, are reported by a majority of patients, regardless of the etiology of EN.
No specific genetic predilection exists except for in relation to the underlying diseases (eg, sarcoidosis is more common in Black individuals). EN can occur at any age, but most cases occur between the ages of 20 and 45, particularly in women. Sex incidence before puberty is about equal.
Löfgren syndrome is a benign variant of sarcoidosis with EN and bilateral enlargement of the hilar lymph nodes. It occurs more commonly in females, especially during pregnancy.
Subacute nodular migratory panniculitis is a variant of EN. It is often unilateral, more focal, and painless. Gradual expansion is characteristic.
L52 – Erythema nodosum
32861005 – Erythema nodosum
Differential Diagnosis & PitfallsOther forms of panniculitis:
- Nodular vasculitis / erythema induratum is typically on the posterior calves.
- Primary infectious panniculitis (see panniculitis) occurs through septic seeding or direct inoculation of a variety of infectious organisms. Tissue culture and polymerase chain reaction (PCR) aids in diagnosis.
- Pancreatic panniculitis favors the lower legs but is often ulcerated.
- Lupus panniculitis favors the face and upper trunk. Most cases are not associated with systemic lupus erythematosus.
- Panniculitis of dermatomyositis (abdomen, thighs, arms) may be the first manifestation of dermatomyositis.
- Granulomatous panniculitis is a manifestation of subcutaneous granuloma annulare or sarcoidosis.
- Cold panniculitis typically presents on the cheeks in children. In adults, it may occur on any body site exposed to cold temperatures. Lateral thigh involvement of horseback riders has been described.
- Injections, including iatrogenic and factitial.
- Alpha-1 antitrypsin deficiency panniculitis is extremely rare in children but has been reported as an initial manifestation of the disease. Lesions frequently ulcerate.
- Subcutaneous T-cell lymphoma
- Furunculosis / carbuncles
- Arthropod bites (insect bites)
- Superficial migratory thrombophlebitis
- Polyarteritis nodosa
- Eosinophilic fasciitis
Drug Reaction DataBelow is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.
Patient Information for Erythema nodosum in Adult
OverviewErythema nodosum is a skin condition characterized by the sudden eruption of tender, red bumps, particularly on the shins. It represents inflammation of the deeper portions of the skin (the adipose tissue, or fatty layer of skin). Erythema nodosum often occurs as an isolated skin finding, or it may be associated with certain medications, infections, or underlying medical conditions.
Who’s At RiskErythema nodosum can develop in persons of any age, sex, and ethnicity. Young adults are particularly susceptible to developing erythema nodosum. Moreover, women are 4 times more likely than men to be affected.
Approximately 30-50% of cases of erythema nodosum have no underlying cause. However, an associated medication, infection, or health condition may be found in the remainder of cases.
Erythema nodosum may develop in people on these medications:
- Birth control pills
- Estrogen pills
- Antibiotics (such as sulfonamides or penicillin)
- Streptococcal infections (such as strep throat)
- Intestinal infections
- Pneumonia (viral or bacterial)
- Fungal infections (such as coccidioidomycosis or histoplasmosis)
- Inflammatory bowel disease (ulcerative colitis or Crohn's disease)
- Lymphoma or leukemia
Signs & SymptomsThe most common locations for erythema nodosum include:
- Knees, ankles, or thighs
- Face and neck
The onset of erythema nodosum may be associated with fever, generalized achiness, leg swelling, or joint pain.
Individual nodules of erythema nodosum usually last from 1-2 weeks, but new lesions may continue to appear for up to 6 weeks. When an individual lesion of erythema nodosum has resolved, it may leave behind a temporary bruise, which subsequently fades to normal-appearing skin.
Self-Care GuidelinesAlthough erythema nodosum may occur on its own, it is more often associated with a medication or with an underlying infection or medical condition. Therefore, it is important to see a physician in order to investigate any possible health problems. In the meantime, however, the tenderness of the skin lesions may be alleviated by the following:
- Restriction of physical activity or bed rest
- Elevation of the legs (if they are affected)
- Cool or warm compresses
When to Seek Medical CareSince erythema nodosum can be associated with underlying infections or health problems, a physician should be consulted within a few days of noticing the skin lesions.
TreatmentsAfter diagnosing you with erythema nodosum, your physician will attempt to identify a possible cause, such as medication, infection, or medical condition. The doctor may order diagnostic tests such as blood work, chest X-ray, or throat culture. If an underlying cause is identified, then the physician will treat it appropriately (for example, by discontinuing a medication, prescribing antibiotics for an infection, or treating a health problem).
Once those investigations and treatments are under way, your health care provider may try the following measures to make you more comfortable:
- Restriction of physical activity or bed rest
- Anti-inflammatory medications such as ibuprofen or aspirin
- Potassium iodide
- Steroids (either taken in pill form or injected directly into the lesions)
Bolognia, Jean L., ed. Dermatology, pp.724, 1455, 1552-1555. New York: Mosby, 2003.
Freedberg, Irwin M., ed. Fitzpatrick's Dermatology in General Medicine. 6th ed, pp.1056, 1059, 1849, 1934, 1944. New York: McGraw-Hill, 2003.
Erythema nodosum in Adult