Publish date: Posted on
Last updated: March 31, 2021
Keywords #
erythema nodosum
septal panniculitis
Diagnosis #
Erythema nodosum (EN) is the most common type of panniculitis, an inflammatory process of the subcutaneous fat.[1,2,3] It is a relatively uncommon dermatologic condition that typically presents as painful, symmetric, erythematous nodules in the pretibial region.1 While it occurs most commonly in women during the second to fourth decades of life, EN can affect any age and either sex.[2] EN may or may not be associated with an underlying disease, and systemic symptoms such as fever, malaise, and arthralgias can be present.[1,2,3]
EN is largely thought to be a delayed hypersensitivity reaction to a variety of antigens, although a trigger is not identified in many cases.[2] Treatment involves addressing the underlying cause, if one can be identified, and is otherwise primarily supportive in nature.[1,2]
Key Concepts #
- EN is an inflammatory process of the subcutaneous fat.
- It usually presents as painful, symmetric, erythematous nodules in the pretibial region.
- Most cases of EN are idiopathic, but infection, certain medications, inflammatory conditions, pregnancy, and malignancy can be precipitating factors.
- EN can be a skin sign of systemic disease, such as sarcoidosis and inflammatory bowel disease, and may inform prognosis.
- The diagnosis is usually clinical, but a biopsy can be performed for confirmation particularly if the presentation is atypical.
- Lesions typically resolve on their own in a matter of weeks to months, but supportive therapy is often employed.
Epidemiology #
The annual incidence of EN is approximately 1 to 5 per 100,000 persons. It is seen most frequently in women (5:1 ratio), particularly during the second to fourth decades of life. Familial cases have also been reported in those that share a common HLA haplotype.[1]
Clinical Features #
- EN presents with painful, symmetric, erythematous nodules on the extensor surfaces of the limbs (most commonly the shins).[1,2,3]
- The absence of ulceration in EN distinguishes it from other forms of panniculitis.[3]
- Systemic symptoms such as fever, malaise, and arthralgias may present several weeks before or coincide with the appearance of lesions.[1,2]
- The lesions of EN may eventually become purpuric/ecchymotic and heal without scarring over several weeks to months. These changes are referred to as ‘erythema contusiformis.’[1]
- EN is associated with several underlying disease processes, such as sarcoidosis and inflammatory bowel disease. It is also associated with infection (particularly streptococcal upper respiratory tract infections), certain medications (oral contraceptives, sulfonamides, penicillin), pregnancy, and malignancy. Despite these associations, more than a third of cases are idiopathic in nature.[3]
Differential Diagnoses #
- Erythema induratum
- Pancreatic panniculitis
- Subcutaneous infection
- Malignant infiltration of the fat
- Cutaneous vasculitis
Diagnostic Workup #
EN is frequently diagnosed clinically. A thorough medication history should be obtained to rule out a medication as the cause.1 Depending on the clinical context, an antistreptolysin O titer, chest x-ray, testing for Mycobacterium tuberculosis and Coccidiodes immitis, and urine pregnancy test should be considered as part of an initial workup.[2]
If a biopsy is performed for diagnostic confirmation, pathology would demonstrate septal panniculitis without vasculitis.[1]
Treatment #
EN is typically self-limiting and resolves without treatment over a course of weeks to months. Inciting medications should be removed from the patient’s regimen and any underlying disease should be managed appropriately.[1,2,3]
Symptomatic treatment usually consists of a combination of bed rest and nonsteroidal anti-inflammatory drugs. Colchicine, dapsone, and potassium iodide have also been successfully employed in the treatment of EN.[1,2,3]
References #
- Blake T, Manahan M, Rodins K. Erythema nodosum – a review of an uncommon panniculitis. Dermatol Online J. 2014 Apr 16;20(4):22376. Review. PubMed PMID: 24746312.
- Gilchrist H, Patterson JW. Erythema nodosum and erythema induratum (nodular vasculitis): diagnosis and management. Dermatol Ther. 2010 Jul-Aug;23(4):320-7. doi: 10.1111/j.1529-8019.2010.01332.x. Review. PubMed PMID: 20666819.
- Patterson, JW & Requena, L. Panniculitis. In: Bolognia JL, Schaffer JV, & Cerroni L, eds. Dermatology. 4th edition. China: Elsevier; 2018: 1733-1757.
