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ANSWER
The correct answer is all of the above (choice “e”). This particular form of tinea capitis is called black dot tinea capitis (BDTC), a somewhat unusual dermatophytosis (superficial fungal infection) that mostly affects children. The causative organisms are anthropophilic—that is, acquired from human sources, such as other children, during activities that involve skin-to-skin contact (eg, sports).
The vast majority of these organisms are from the Trichophyton family, such as T tonsurans or T violaceum. They invade the hair shaft itself, leaving the hard covering (the cuticle) intact. The black dots represent the tips of broken-off hairs, themselves full of fungal elements, seen in the photomicrograph. The term endothrix is given to this kind of fungal infection, in which the organisms are contained within the hair shaft, which, as a result, becomes brittle and breaks off. This is a relatively common type of infection.
A more unusual form of tinea capitis is caused by zoophilic organisms, such as Microsporum canis (from dogs and cats), Microsporum gypseum (pigs or cows), or T equinum (horses). These infect the external surface of the hair shaft, breaking down the cuticle. This allows for identification of the infection by Wood’s lamp, which causes the affected area to turn a yellowish color. These infections also tend to provoke a more brisk inflammatory response in the victim and are more difficult to treat.
Diagnosis can be made from a combination of clinical findings, KOH prep (as in this patient), and/or fungal culture.
Treatment can entail griseofulvin or terbinafine; the case patient was treated with a two-month course of the latter (125 mg/d). Topical treatment is of limited usefulness.
ANSWER
The correct answer is all of the above (choice “e”). This particular form of tinea capitis is called black dot tinea capitis (BDTC), a somewhat unusual dermatophytosis (superficial fungal infection) that mostly affects children. The causative organisms are anthropophilic—that is, acquired from human sources, such as other children, during activities that involve skin-to-skin contact (eg, sports).
The vast majority of these organisms are from the Trichophyton family, such as T tonsurans or T violaceum. They invade the hair shaft itself, leaving the hard covering (the cuticle) intact. The black dots represent the tips of broken-off hairs, themselves full of fungal elements, seen in the photomicrograph. The term endothrix is given to this kind of fungal infection, in which the organisms are contained within the hair shaft, which, as a result, becomes brittle and breaks off. This is a relatively common type of infection.
A more unusual form of tinea capitis is caused by zoophilic organisms, such as Microsporum canis (from dogs and cats), Microsporum gypseum (pigs or cows), or T equinum (horses). These infect the external surface of the hair shaft, breaking down the cuticle. This allows for identification of the infection by Wood’s lamp, which causes the affected area to turn a yellowish color. These infections also tend to provoke a more brisk inflammatory response in the victim and are more difficult to treat.
Diagnosis can be made from a combination of clinical findings, KOH prep (as in this patient), and/or fungal culture.
Treatment can entail griseofulvin or terbinafine; the case patient was treated with a two-month course of the latter (125 mg/d). Topical treatment is of limited usefulness.
ANSWER
The correct answer is all of the above (choice “e”). This particular form of tinea capitis is called black dot tinea capitis (BDTC), a somewhat unusual dermatophytosis (superficial fungal infection) that mostly affects children. The causative organisms are anthropophilic—that is, acquired from human sources, such as other children, during activities that involve skin-to-skin contact (eg, sports).
The vast majority of these organisms are from the Trichophyton family, such as T tonsurans or T violaceum. They invade the hair shaft itself, leaving the hard covering (the cuticle) intact. The black dots represent the tips of broken-off hairs, themselves full of fungal elements, seen in the photomicrograph. The term endothrix is given to this kind of fungal infection, in which the organisms are contained within the hair shaft, which, as a result, becomes brittle and breaks off. This is a relatively common type of infection.
A more unusual form of tinea capitis is caused by zoophilic organisms, such as Microsporum canis (from dogs and cats), Microsporum gypseum (pigs or cows), or T equinum (horses). These infect the external surface of the hair shaft, breaking down the cuticle. This allows for identification of the infection by Wood’s lamp, which causes the affected area to turn a yellowish color. These infections also tend to provoke a more brisk inflammatory response in the victim and are more difficult to treat.
Diagnosis can be made from a combination of clinical findings, KOH prep (as in this patient), and/or fungal culture.
Treatment can entail griseofulvin or terbinafine; the case patient was treated with a two-month course of the latter (125 mg/d). Topical treatment is of limited usefulness.
An 8-year-old boy is brought in by his mother for evaluation of a scalp condition that manifested several months ago. The first sign was hair loss in several locations, mostly on the sides, followed in a few weeks by faint scaling. As more hair came out, the scaling in the affected locations reduced, but uniformly spaced black dots began to appear. There has never been any redness. The boy was taken to a local urgent care center, where he was diagnosed with probable “ringworm” and given a prescription for topical antifungal cream (clotrimazole, bid application). This failed to help, so the family sought an appointment with dermatology. Additional history-taking reveals that the boy noticed the problem within a few weeks of starting wrestling at school. Examination of the scalp reveals several round areas of partial and uniform hair loss, averaging 3 cm in diameter. No redness or edema is seen, and only very faint scaling is observed on the surface of the skin. Distinct black dots are uniformly distributed within the lesions. A vigorous scrape of one of the areas is processed with potassium hydroxide 10% and examined under 10x magnification. The black dots are found to be broken-off hairs filled with hundreds of tiny round spheres. Several hyphae are seen adjacent to the hairs. Palpation reveals adenopathy in the adjacent nuchal scalp and neck. Wood’s lamp examination fails to highlight these areas.
