A kerion is a tinea infection with a severe hypersensitivity reaction to the dermatophyte.
Synonym: kerion Celsi (Celso's kerion)
Kerions are most commonly associated with tinea capitis but can occur in other sites with hair such as the pubic region. Dermatophytes that invade hair (endothrix) and that cause inflammation are involved.
Clinical features:
(1) The patient has painful plaques or nodules that may be inflamed, edematous and boggy. The lesions may appear as an exophytic mass.
(2) The lesions are often crusted.
(2) There may be variable purulent drainage.
(3) Regional lymphadenopathy is common (posterior cervical nodes for tinea capitis)
The inflammatory reaction may be severe enough to be mistaken for cellulitis. However, a kerion may become superinfected, which can lead to sepsis.
The diagnosis can be made clinically but must be supported by fungal and bacterial cultures. Microscopic examination of infected hairs can be helpful in some cases.
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