Erythema Nodosum in Children with Tinea Capitis on the Scalp

Tinea Capitis Triggers the Immune System in Multiple Ways

Erythema Nodosum or “EN” is an inflammatory condition of the deep fat. In medical terms, inflammation of the deep fat is known as a panniculitis. Affected patients with erythema nodosum often develop red, painful tender lumps and nodules on the front of the legs (shin area) but the forearms, thighs and trunk can be affected as well. These areas may look like bruises at first glance. They range in size from a dime to a quarter. to grapefruit size. They last about 2 weeks but can take about 2 months to fade completely. As the lesions of EN fade, they may look like a bruise.

About 1 to 5 out of every 100,000 people can develop EN. Children and young adults are particularly affected. In the early days of EN just prior to the skin lesions developing, affected patients have a confusing “prodrome” which includes fever, malaise, weight loss and cough. Labs tests might show elevated ESR and CRP and elevated white blood cell counts.

About 55 % of patients with EN have no clear cause. However, it’s well recognized that certain infections, certain medical conditions and certain medications can be associated with EN. Streptococcal infections are among the most common causes on EN. In fact, about 44 % of cases in adults are due to Streptococcal infections and this number rises to about 48 % in children.

a) EXAMPLES OF INFECTIONS CAUSING EN

Streptococcal infections (Strep pharyngitis is a common cause), TB, histoplasmosis, tinea capitis, Yersinia, Chlamydia, Hepatitis B, Hepatitis C, HIV, Herpes simplex virus,

b) EXAMPLES OF MEDICAL CONDITIONS CAUSING EN

Cancer (lymphoma, leukemia), ulcerative colitis, sarcoidosis (one quarter of cases), pregnancy (5% of cases)

c) EXAMPLES OF MEDICATIONS CAUSING EN

Antibiotics (sulfa drugs, amoxicillin), bromides, iodides, oral contraceptives, Proton pump inhibitors

EN appears to be due to immune system activation by various antigens. In the case of EN associated with infection, it appears that the infection activates the immune system and the skin inflammation can occur at a distant site even though there are no infectious particles found at that distant site. It appears that EN is due to a type IV delayed hypersensitivity response to numerous antigens. Other theories suggest that antibody-antigen complexes trigger the reaction.

The work up for EN involves a search for the trigger. A chest x-ray, throat swab & ASO titers, PPD test and blood work (ESR, CRP, CBC, culture) may be part of the work up. A biopsy can be diagnostic in challenging cases. The biopsy will show a typical septal panniculitis without evidence of vasculitis.

EN is treated by treating the underlying disorder that caused it in the first place. For example, if the EN is due to an infection, the infection must be eradicated. if EN is due to a medication, the medication may need to be stopped. The pain of EN is often managed with non-steroidal anti-inflammatory medications.

EN from Tinea Capitis: Salah NB et al. 2021

Salah and colleagues recently presented three interesting cases of EN associated with kerion type tinea capitis of the scalp. The patients in the report were 3 boys age 4, 9 and 14 who developed EN associated with T. mentagrophytes associated tinea capitis. Lesions appears 1-3 weeks after starting griseofulvin for their tinea capitis.

The lesions of EN resolved spontaneously over time with continued use of griseofulvin

CONCLUSIONS and COMMENTS

Erythema nodosum is important to know about. In the case of tinea capitis associated EN, the skin inlammation may occur after the antifungal medication is started prompting many to consider whether the skin inflammation is in fact an allergic drug reaction. The most important part of treating EN due to tinea is to continue the treatment for the tinea rather than stopping the medication!

REFERENCE

Salah NB et al. Erythema nodosum in patients with kerion of scalp. Clin Exp Dermatol. 2021 Dec;46(8):1577-1578.

Kakourou T, Drosatou P, Psychou F, Aroni K, Nicolaidou P. Erythema nodosum in children: a prospective study. J Am Acad Dermatol. 2001;44:17–21.

Mert A, Ozaras R, Tabak F, Pekmezci S, Demirkesen C, Ozturk R. Erythema nodosum: an experience of 10 years. Scand J Infect Dis. 2004;36:424–7.