A kerion is not an infectious agent in itself rather a kerion is the skin leison that develops when an infectious agent that normally causes scalp ringworm (tinea capitis) becomes more aggressive. Deep boggy red areas characterized by a severe acute inflammatory infiltrate with pustule formation are termed kerions or kerion celsi. Normally, scalp ringworm inducing agents cause circular patches of red crusty skin. Although not pleasant, the problem is relatively mild and reversible with proper treatment. However, if the infection gets out of hand a kerion may develop.
When a kerion develops it first starts out as a more typical presentation of tinea capitis with a flaky, crusty patch of skin on the scalp. This can quickly deteriorate into a boggy, puritic mass of inflamed tissue. This is a kerion. The kerion can deteriorate to a nasty, deep abscess if it is not treated correctly. This has the potential to to elicit scarring and permanent alopecia. When a kerion develops with severe inflammation it is fairly common for the regional lymph nodes in the neck to become enlarged (called cervical lymphadenopathy). Suppuration and kerion formation are more commonly are typically associated with Trichophyton tonsurans (dermatophytes) infection. Kerion formation with other infectious agents that cause tinea capitis are less likely, but still possible.
Sometimes Kerion Celsi is confused with other conditions due to a lack of diagnostic testing. In one report, some patients were hospitalized with the diagnosis of Staphylococcal abscess while a microbiological diagnostic test would have shown the cause was due to Trichophyton verrucosum infection resulting in a kerion (Zaror, 1995). Occasionally, a kerion can look much like some forms of scarring alopecia such as dissecting cellulitis or erosive pustular dermatosis. Because of this apparent similarity in presentation, the doctor needs to be very careful in their investigation and knowledgeable about the potential for confusing kerions with other diagnoses. The patient who suspects they have a kerion caused by an infectious agent or something similar needs to find an experienced dermatologist to improve the chances of getting a correct diagnosis. The average general practitioner is probably not in a position to make a kerion diagnosis with confidence.
Early initiation of treatment is extremely important with kerions. The sooner treatment is started the less likely the kerion will promote a permanent scarring alopecia. Unfortunately, some reports suggest that rapid diagnosis and treatment of kerions only occurs in a minority of cases or that kerions are often misdiagnosed. There seems to be a certain lack of knowledge about tinea capitis and kerions among some general practitioners and this can lead to a delay in receiving proper treatment. The longer kerions persist the more damaging they become. When a kerion is diagnosed, the typical immediate treatment response is a course of "Griseofulvin", an anti fungal agent. Most patients with kerions and a primary diagnosis of tinea capitis also have a secondary bacterial infection of the kerion. Griseofulvin is not good for treating bacterial or yeast infections so other anti-bacterial treatments may be given along with the Griseofulvin. Some published case reports have indicated the newer anti fungal agents Itraconazole and Terbinafine have also been successfully used to treat kerions. Sometimes oral corticosteroids are also given in addition to the anti fungal agent, although the few published studies comparing treatments with and without corticosteroids have shown little added benefit. However in principle, oral corticosteroids should help reduce the inflammation in the kerion. Topical corticosteroids are not used as this can complicate the local fungal infection.
