ABSTRACT
Most cases of tinea capitis (fungal infection of scalp hair) seen in North America are caused by Trichophyton tonsurans, a large-spore endothrix infection. Microsporum canis (ectothrix) is also found occasionally. Different species may be more prevalent in other parts of the world. The fungus invades and multiplies within the hair shaft below the surface of the skin, causing hair fragility and breakage. This results in bald spots with follicular ostia filled with keratinous debris or ‘black dots’, the residua of infected, pigmented hair shafts (Figure 26.1). Variable degrees of inflammation may be seen, ranging from none (no erythema or scaling) to highly inflamed, purulent, edematous and crusted plaques (kerion; Figure 26.2). Pustular lesions on the scalp should always raise suspicion for tinea capitis. Tinea capitis almost always affects children, and African American children seem to be especially prone to infection. Any inflamed or scaly bald spot on the scalp of an African American child should be considered to be tinea capitis unless proven otherwise. However, adults of all races (but especially African American women) can also be affected. If treated early, tinea capitis heals without scarring or hair loss. However, highly inflammatory lesions or untreated lesions may eventuate in permanent hair loss. Inflammatory tinea capitis is one of several causes of ‘tufted folliculitis’ (polytrichia).
