Kerion in Adult
See also in: Cellulitis DDx,Hair and ScalpAlerts and Notices
Synopsis
A kerion will occur in a patient who has an intact immune response and develops an intense inflammatory response to the organisms. It is almost exclusively seen in children, but on rare occasions, it may be seen in adolescents and young adults. As in tinea capitis, this disease is more common in patients of African descent. It is more common in males than females and in those with short hair. Other risk factors include diabetes, anemia, immunosuppression, underlying malignancy, and organ transplantation. It is seen less frequently in HIV-infected patients; this may be due to increased colonization with Malassezia, which may inhibit dermatophyte colonization.
Fever, pain, occipital lymphadenopathy, and secondary bacterial infection may be associated. The intensity of the inflammation depends on the host immune response. If left untreated, scarring and permanent alopecia can develop. Patients with kerion may develop immunological dermatophytid reactions, which may be localized or generalized. The "ear sign" is a dermatophytid reaction that presents as erythematous plaques and papules on the helix, antihelix, and retroauricular region.
Kerions can be distinguished from cellulitis based on their location and the presence of other signs of a fungal infection, such as scaling.
Codes
ICD10CM:B35.0 – Tinea barbae and tinea capitis
SNOMEDCT:
19087001 – Kerion
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
- Pustules, tenderness, and inflammation often mimic a bacterial infection or abscess.
- Kerion formation may mimic acne keloidalis nuchae and folliculitis decalvans.
- Psoriasis
- Seborrheic dermatitis
- Contact dermatitis
- Carbuncle
- Furunculosis
- Zoster
- Dissecting cellulitis of the scalp
- Nonbullous impetigo
- Pseudolymphoma
- Pemphigus foliaceus or vulgaris
- Cicatricial pemphigoid
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Management Pearls
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Therapy
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References
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Last Reviewed:04/02/2019
Last Updated:04/11/2022
Last Updated:04/11/2022
Patient Information for Kerion in Adult
Overview
A kerion is a scalp condition that occurs in severe cases of scalp ringworm (tinea capitis). A kerion appears as an inflamed, thickened, pus-filled area, and it is sometimes accompanied by a fever.The underlying condition, scalp ringworm, is a usually harmless fungal infection of the scalp and hair that is seen as scaly spots and patches of broken hair on the head. Ringworm of the scalp is most commonly seen in children.
Scalp ringworm is acquired by direct contact with infected people or with contaminated objects that have been handled by infected people (such as combs, pillows, and sofas).
A kerion is believed to be an overly active response of the immune system or an allergic reaction to the fungus.
Who’s At Risk
Scalp ringworm may occur in people of all ages, of all races, and of both sexes. It occurs most commonly in children, but it may be seen in teens and young adults.Signs & Symptoms
A kerion appears as a thick, mushy area of the scalp. Its surface is often studded with pus-filled bumps (pustules). The kerion can break open and drain pus. If untreated, a kerion can lead to scarring and permanent hair loss (alopecia).Fever and pain may accompany the kerion. In addition, the lymph nodes at the back of the scalp, behind the ears, or along the sides of the neck may be swollen.
Self-Care Guidelines
There are no effective self-care measures to treat a kerion.When to Seek Medical Care
See a doctor for evaluation of hair loss or itchy, scaly spots on the scalp. If you develop a thick, pus-filled pocket on the scalp, see the doctor soon to evaluate for kerion.Treatments
Often, the doctor is able to diagnose a kerion just by looking at it.To confirm the diagnosis, the health care provider may scrape some surface skin scales onto a slide and examine them under a microscope. This procedure, called a KOH (potassium hydroxide) preparation, allows the doctor to look for tell-tale signs of fungal infection.
Sometimes the doctor will also perform a fungal culture to document the presence of fungus or to discover the particular organism that is causing the kerion. The procedure involves:
- Plucking a few hairs or piercing any pus-filled lesions in the involved areas of the scalp
- Rubbing a sterile cotton-tipped applicator across the skin to collect scale and pus
- Sending the specimen away to a laboratory
Occasionally, a Wood's lamp is used to look for the fungus. In this procedure, the doctor shines a black light at the scalp. Certain dermatophytes appear as yellow-green fluorescent spots when seen under this light.
A kerion is treated with oral antifungal medicines because the fungus grows deep into the hair follicle where topical creams and lotions cannot penetrate. Scalp ringworm and kerion usually require at least 6-8 weeks of treatment with oral antifungal pills or syrup, including:
- Griseofulvin
- Terbinafine
- Itraconazole
- Fluconazole
- Selenium sulfide shampoo
- Ketoconazole shampoo
If the kerion is particularly tender and painful, prescription oral corticosteroids (cortisone pills or syrup) may help. Steroids are strong medications that can quickly reduce the inflammation.
References
Bolognia, Jean L., ed. Dermatology, pp.1179-1180. New York: Mosby, 2003.
Freedberg, Irwin M., ed. Fitzpatrick's Dermatology in General Medicine. 6th ed. pp.1861, 1994. New York: McGraw-Hill, 2003.
Kerion in Adult
See also in: Cellulitis DDx,Hair and Scalp