Kerion or kerion celsi is an acute inflammatory process which is the result of the host's response to a fungal

ringworm Dermatophytosis, also known as ringworm, is a fungal infection of the skin. Typically it results in a red, itchy, scaly, circular rash. Hair loss may occur in the area affected. Symptoms begin four to fourteen days after exposure. Multiple a ...

infection of the

hair follicle The hair follicle is an organ found in mammalian skin. It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regulates hair growth via a complex interaction between h ...

s of the

scalp The scalp is the anatomical area bordered by the human face at the front, and by the neck at the sides and back. Structure The scalp is usually described as having five layers, which can conveniently be remembered as a mnemonic: * S: The ski ...

(occasionally the

beard A beard is the hair that grows on the jaw, chin, upper lip, lower lip, cheeks, and neck of humans and some non-human animals. In humans, usually pubescent or adult males are able to grow beards. Throughout the course of history, societal at ...

) that can be accompanied by secondary bacterial infection(s). It usually appears as raised, spongy lesions, and typically occurs in children. This honeycomb is a painful inflammatory reaction with deep suppurative lesions on the scalp. Follicles may be seen discharging pus. There may be sinus formation and rarely mycetoma-like grains are produced. It is usually caused by

dermatophytes Dermatophyte (from Greek '' derma'' "skin" (GEN ''dermatos'') and ''phyton'' "plant") is a common label for a group of fungus of ''Arthrodermataceae'' that commonly causes skin disease in animals and humans. Traditionally, these anamorphic (as ...

(fungal infections of the skin affecting humans and animals) such as ''

Trichophyton verrucosum ''Trichophyton verrucosum'', commonly known as the cattle ringworm fungus, is a dermatophyte largely responsible for fungal skin disease in cattle, but is also a common cause of ringworm in donkeys, dogs, goat, sheep, and horses. It has a worldw ...

'', '' T. mentagrophytes'', and ''

Microsporum canis ''Microsporum canis'' is a pathogenic, asexual fungus in the phylum Ascomycota that infects the upper, dead layers of skin on domesticated cats, and occasionally dogs and humans. The species has a worldwide distribution. Taxonomy and evolution ...

''. Treatment with oral

griseofulvin Griseofulvin is an antifungal medication used to treat a number of types of dermatophytoses (ringworm). This includes fungal infections of the nails and scalp, as well as the skin when antifungal creams have not worked. It is taken by mouth. C ...

common.

Symptoms

There may be loss of hair as hair will come out easily. Sometimes, there is growth of organisms. Lymph and fever symptoms may be present. This condition can be mistaken for a case of

impetigo Impetigo is a bacterial infection that involves the superficial skin. The most common presentation is yellowish crusts on the face, arms, or legs. Less commonly there may be large blisters which affect the groin or armpits. The lesions may be pa ...

Diagnosis

The basis for the diagnosis of kerion is clinical finding, positive microscopic examinations (such as positive KOH preparation, Lactophenol cotton blue wet mount, Chicago sky blue stained (CSB) slide, Calcofluor white stained slide, Periodic acid–Schiff stained slide, and Gomori’s methenamine silver stained slide), mycological culture and modern molecular tests (such as PCR-reverse line blot test, real-time PCR test, multiplex PCR test, PCR-ELISA test, and MALDI-TOF test) of clinical specimens. Wood's lamp (blacklight) examination will reveal a bright green to yellow-green fluorescence of hairs infected by ''Trichophyton mentagrophytes var. Mentagrophytes'', in kerion infection caused by ''Trichophyton verrucosum'' Invaded hairs show an ectothrix infection and fluorescence under Wood's ultra-violet light has been noted in cattle but not in humans.

Differential Diagnosis (D/D)

Kerion has been called a great mimicker. It can be easily confused with bacterial scalp abscess and various other conditions. In a recent report, a previously well 9-year-old boy presented to the outpatients’ clinic with a tender, swollen occipital scalp lesion progressing over one month’s duration. He was initially misdiagnosed as having a

bacterial infection Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and are often beneficial but others can cause infectious diseases. The number of ...

, and was given a 2 weeks’ course of oral

cephalexin Cefalexin, also spelled cephalexin, is an antibiotic that can treat a number of bacterial infections. It kills gram-positive and some gram-negative bacteria by disrupting the growth of the bacterial cell wall. Cefalexin is a beta-lactam antibi ...

. No improvement was noticed after the course. It was only after the scalp scrapings were examined, that the child was found to be having a local infection with the fungus ''

Trichophyton tonsurans ''Trichophyton tonsurans'' is a fungus in the family Arthrodermataceae that causes ringworm infection of the scalp. It was first recognized by David Gruby in 1844. Isolates are characterized as the "–" or negative mating type of the '' Arthrode ...

'', which had resulted in kerion. Antifungal therapy was then started, which resulted in complete cure.

Treatment

Unlike most other manifestations of Tinea dermatophyte infections, Kerion is not sufficiently treated with topical antifungals and requires systemic therapy. Typical therapy consists of oral antifungals, such as griseofulvin or terbinafine, for a sustained duration of at least 6-8 weeks depending on severity. Successful treatment of kerion often requires empiric bacterial antibiotics given the high prevalence of secondary bacterial infection.

References

External links