Kerion:
A parent's guide to condition and treatment information

Often, the doctor is able to diagnose a kerion just by looking at it. However, in order to confirm the diagnosis, the physician may wish to 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 in order to document the presence of fungus or to discover the particular organism that is causing the kerion. The procedure involves:

1. Plucking a few hairs or piercing any pus-filled lesions in the involved areas of the scalp
2. Rubbing a sterile cotton-tipped applicator across the skin to collect scale and pus
3. Sending the specimen away to a laboratory

Typically, the laboratory will have results within 2–3 weeks. In some cases, the laboratory is able to identify the particular type of dermatophyte that is causing the scalp ringworm and kerion. The doctor may also perform a bacterial culture in the same manner to see if there is a bacterial infection present.

Occasionally, a Wood's lamp is used to look for the fungus. In this procedure, the doctor shines a black light at the scalp, and certain strains of dermatophytes may 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
• Ketoconazole

Often, the doctor will also prescribe a medicated shampoo to reduce the risk of spreading the infection to someone else:

• Selenium sulfide shampoo
• Ketoconazole shampoo

If the bacterial culture is positive (shows bacterial growth), the physician may want to start your child on an oral antibiotic as well.  

If the kerion is particularly tender and painful, your child's doctor may recommend starting oral corticosteroids (cortisone pills or syrup). Steroids are strong medications that can quickly reduce the inflammation present in the kerion.