An 11-year-old boy has a history of 2 months of progressive patchy hair loss (Figure 143-1). He has some itching of the scalp, but his mother is worried about his hair loss. Physical examination reveals alopecia with scaling of the scalp and broken hairs looking like black dots in the areas of hair loss. A KOH preparation is created by using a #15 scalpel to scrape some scale and small broken hairs onto a slide. With the help of a fungal stain and KOH, branching septate hyphae are seen under the microscope. The most likely cause of this tinea capitis is Trichophyton tonsurans; therefore 4 weeks of oral terbinafine is prescribed. The tinea capitis fully resolves and the hair does grow back over time.
Tinea capitis in a young black boy. The most likely organism is Trichophyton tonsurans. (Reproduced with permission from Richard P. Usatine, MD.)
Tinea capitis is a fungal infection involving the scalp and hair. Common signs include hair loss, scaling, black dots, erythema, and impetigo-like plaques.
Tinea capitis is the most common type of dermatophytoses in children younger than 10 years (Figures 143-1, 143-2, 143-3, 143-4, 143-5). It is much less common after puberty or in adults. The infection has a worldwide distribution.
Tinea capitis is more common in young African-American children.1 Boys are infected more often than girls.1
Combs, brushes, couches, and sheets may harbor the live dermatophyte for a long period of time.
Spread from person to person with direct contact or through fomites (especially Trichophyton tonsurans).
Occasionally spread from cats and dogs to humans (especially Microsporum species).
Tinea capitis with patchy hair loss and scaling of the scalp in a young boy. (Reproduced with permission from Richard P. Usatine, MD.)
A kerion resulting from inflammation of the tinea capitis on this young boy. The kerion looks superinfected, but it is nothing more than an exuberant inflammatory response to the dermatophyte. (Reproduced with permission from Richard P. Usatine, MD.)
Close-up of black dot alopecia in a 7-year-old girl showing the black dots where infected hairs have broken off. (Reproduced with permission from Richard P. Usatine, MD.)
ETIOLOGY AND PATHOPHYSIOLOGY