Review Question - QID 102956

This patient is presenting with tinea capitis. Although there are multiple etiologies, fluorescence under Wood's UV lamp indicates microsporum canis infection.

Tinea capitis is a fungal infection causing ring-shaped lesions on the scalp. The infection is most often caused by dematophytes in the genera Microsporum and Trichophyton. These can be differentiated with the Wood's UV lamp, as Microsporum fluoresces while Trichophyton does not. Tinea capitis is most commonly seen in children, but is also prevalent in immunocompromised adults.

Andrews et al. reviews the diagnosis and management of common tinea infections in children. Tinea infections are contagious and most often develop following direct contact with humans or animals that are infected, or indirectly from surfaces or soil that are contaminated. Diagnosis is often derived from history and physical examination and KOH microscopy. While most tinea infections typically responds to topical anti-fungal therapy, some tinea infections, including tinea capitis, require oral anti-fungal medications such as terbinafine, fluconazole, itraconazole, or griseofulvin.

Shermer et al. performed a study comparing the efficacy of griseofulvin and fluconazole treatment in decreasing the transmission of tinea capitis in children. Ninety patients were followed, the majority with either Trichophyton violaceum or Microsporum canis infection. They found that both griseofulvin and fluconazole treatment decreased risk of transmission and that there was no significant difference between the two treatments.

Figure A shows a ring-shaped, scaly eruption on the scalp of a child with microsporum canis infection.

Incorrect Answers:
Answer 1: Malassezia furfur is a common cause of tinea versicolor, a cutaneous mycosis that presents as hypo- and hyper-pigmented patches of skin.
Answer 2: Trichophyton tonsurans is a common cause of tinea capitis; however, it does not fluoresce under Wood's UV lamp exam.
Answer 3: Trypanosoma cruzi is a protozoa that causes Chaga's disease.
Answer 4: Toxocara canis is a nematode that causes visceral larva migrans.