A boy with multiple patches of alopecia and an affected cat

A 7-year-old boy presented with itching, scaling, and areas of hair loss in the left parietal area on the scalp of 6 weeks duration (Figures 1 and 2). His past health was unremarkable. Family members were not affected.

Figure 1.

Multiple lesions on scalp of a boy with a cat with skin disease Over 10 coin-size scalp lesions, 3 to 5 cm in diameter. Some of the scalp lesions were inflammatory with erythema and crusting in the early phrase.

Figure 2.

Left parietal lesions.

Physical examination revealed patches of fine scaling, patchy hair loss with broken hair shafts, and a black dot appearance in the left parietal area. The hair in the affected area was of irregular length. The hair-pull test was negative. [The test is conducted at more than three locations on the scalp and is used for monitoring alopecia areata, acute cases of telogen effluvium, anagen effluvium, and loose anagen syndrome. The results are considered positive if more than 10% of hairs in a pulled bundle are removed]. There was no cervical, occipital, or postauricular lymphadenopathy. The rest of the physical examination was unremarkable.

Discussion

A clinical diagnosis of noninflammatory tinea capitis was made based on the history of an affected cat at home and findings of multiple patches of alopecia with fine, white, adherent scaling of the scalp. The diagnosis was confirmed by potassium hydroxide wet-mount examination of scalp scrapings of the active border of an alopecic lesion, which showed septate hyphae and fungal spores. Culture of scalp wounds yielded Microsporum canis.

Tinea capitis, also known as ‘ringworm of the hair or the scalp’, is a cutaneous fungal infection (dermatophytosis) of the scalp (1). The disease is primarily caused by dermatophytes in the Trichophyton and Microsporum genera. Tinea capitis is usually found in prepubertal children with a peak incidence at 6 to 10 years of age (2).

Children often become infected by spores shed by a household contact. Animal-to-human transmission is also common. The fungus commonly occurs on the skin of pets (dogs, cats) and an individual can acquire the infection while petting or grooming an animal (3,4).

Noninflammatory tinea capitis typically presents as single or multiple patches of well-demarcated area (s) of alopecia with fine scale, studded with broken off hairs at the skin line, resulting in a ‘black dot’ appearance, as is illustrated in the present case. Itching of the scalp is common. Patients with tinea capitis may have erythematous papules, scaling, or plaques over the helix, antihelix, and retroauricular region, referred to as the ‘ear sign’ (5).

The differential diagnosis for noninflammatory tinea capitis includes seborrhoeic dermatitis, pityriasis amiantacea, alopecia areata, trichotillomania, traction alopecia, loose anagen syndrome, plaque psoriasis, and pediculosis capitis.

Alternatively tinea capitis can be inflammatory and then presents as (i) diffuse, patchy alopecia with scattered pustules or low-grade folliculitis, (ii) painful and suppurative boggy edematous plaques or nodules often associated with purulent drainage (kerion), or (iii) yellow or honey-coloured, cup-shaped, follicular crusts grouped in patches like a honeycomb, known as scutula (favus).

The diagnosis of tinea capitis is mainly clinical, based on the characteristic morphological features (1). With a Wood’s lamp, hairs infected by Trichophyton tonsurans, the most common cause of tinea capitis, do not fluoresce (3). On the other hand, Wood’s lamp examination may reveal bright green to yellow-green fluorescence of hairs infected by Microsporum canis, Microsporum audouinii, Microsporum rivalieri, and Microsporum ferrugineum and a dull green or blue-white fluorescence of hairs infected by Trichophyton schoenleinii (6). Typical dermoscopic findings include white perifollicular scales, broken hairs, dystrophic hairs, comma hairs, zigzag hairs, corkscrew hairs, bar code-like hairs, and black dots (7,8). If necessary, the diagnosis can be confirmed by potassium hydroxide wet-mount examination of skin scrapings taken from the active border of the lesion which show septate hyphae and fungal spores. If the test is negative and a fungus infection is suspected, the scrapings should be sent for culture (3).

The treatment of choice for tinea capitis is oral griseofulvin. The recommended paediatric dosage is 10 mg/kg/day for 6 to 8 weeks (1,9,10). The efficacy of this treatment is reported to be in the range of 88 to 100% (11). Other oral antifungal treatments for tinea capitis include terbinafine, itraconazole, and fluconazole, with the advantage of shorter treatment durations than griseofulvin (9). Referral to a dermatologist is indicated if the disease is severe, especially with atypical forms mimicking atopic dermatitis, impetigo, lupus erythematosus, and periorificial dermatitis, and if response to initial treatment is suboptimal (12).

Informed consent: Informed consent was obtained from the patient’s family.

Funding: There are no funders to report for this submission.

Potential Conflicts of Interest: AKCL serves on the editorial board of Paediatrics & Child Health. Another editor was responsible for overseeing the peer review process for this manuscript. There are no other disclosures. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.