Demodex is a commensal mite found in the pilosebaceousunits. Demodicosis in scalp is uncommon and only few cases were reported on the literature. We described a young caucasian male with burning, scaling and pustules on the scalp. The scalp biopsy showed granulomatous reaction and presence of Demodex mites in follicular canals. The diagnose of demodex folliculitis of the scalp was made and a good response was achieved after topical metronidazole treatment.
Demodex; Demodicosis; Folliculitis; Metronidazole; Rosacea; Rosacea-like; Scalp; Therapy
Demodex is a commensal mite found in the pilosebaceous units. The three mainly demodicosis clinical forms described in facial skin are: pityriasisfolliculorumwhich presents facial erythema, burning, scales and follicular plugs; rosacea-like demodicosischaracterized by scales, erythema and papulopustules very similar with rosacea and demodicosis gravis also called granulomatous rosacea-like .
Demodex can also occur associate with others skin conditions such as perioral dermatitis, rosacea and seborrehoeic dermatitis, called secondary demodicosis by some authors . The clinical diagnose of demodicosis can be difficult due its clinical signs are common with other skin disorders.
A 19-year-old caucasian male presented burning sensation, scaling on the center facial and scalp for the last four months. He had been treated before by another dermatologist with anti-seborrheic facial soap and corticosteroids shampoo without success. He had a medical record of atopic dermatitis, allergic rhinitis and penicillin allergy.
On clinical examination, he had some pustules on the nose and erythematous plaques with fatty scaling on glabella, nasolabial sulcus and chin. The dermoscopy on the vertex scalp revealed scaling, follicular pustules, crusts, perifollicular and interfollicular erythema (Figure1).There was no ocular symptoms. The diagnosis of facial and scalp seborrheic dermatitis was made. Doxycycline 100mg daily, ketoconazole 2% cream, ketoconazole 2% shampoo and clobetasol propionate 0.05% scalp solution was prescribed and there has been improvement on the facial and scalp lesions. After 2 weeks without treatment, the scalp lesions relapsed. Dermoscopy presented perifollicular erythema,pustules and crusts on vertex scalp. A bacterial folliculitis was suspected, It was prescribed oral sulfamethoxazole plus trimethoprim during four weeks without success.
Figure 1: The dermoscopy on the vertex scalp revealed follicular pustules, crusts, perifollicular and interfollicular erythema.
In order to elucidate the diagnosis, a scalp biopsy was performed. The histopathological examination revealed superficial folicullitis, interfolicular granulomatous reaction on dermis (Figure 2) and presence of Demodex in some hair follicles (Figure 3). No bacterial colonies or fungal were found. Firstly me consider a scalp rosacea diagnose, but the absence of clinical signs for facial rosacea led us to the diagnosis of scalp demodicidosisfollicullites. Tetracycline 500mg and metronidazole solution on scalp was prescribed for four weeks. After one year of follow up, the patient remained asymptomatic.
Histopathological scalp exam showed granulomatous reaction on dermis.
Presenceof Demodex inside the follicular canal.