Tinea

Mycoses are a heterogeneous group of disorders of glabrous skin, associated structures and mucous membranes caused by dermatophytes, yeasts and moulds. Dermatophytes are keratinophilic and keratinolytic fungi subdivided according to their saprophitic stage into Microsporum, Trichophyton, Epidermophyton. Dermatophytoses are classified into dermatophytoses of the glabrous skin, epidermic (tinea corporis, faciei, of the hands and feet), of the scalp (tinea capitis) and of the nails (onychomycosis).

Signs and symptoms

Tinea corporis

This presents with one or several erythematous-squamous patches which spread centrifugally and, because they tend to resolve centrally, form an annular shape. Small vesicles may be observed on the distinct and raised margins. Sometimes a rosette pattern may be observed due to a recurrence of infection in the central part. Some pathogens produce exudative forms characterised by vesicular, vesicular-pustular or pustular lesions; the number of patches varies and usually there is associated pruritus. The aetiological agents at play are Trichophyton tonsurans, Microsporum canis, Trichophyton mentagrophytes, and Trichophyton rubrum.

Tinea faciei

Dermatophyte infection of the glabrous skin on the face. It is very common in children, in whom it presents with one or several erythematous-squamous roundish patches, with distinct margins and tending towards central resolution. It may affect the eyelashes and eyebrows. Sometimes the lesions are erythematous-oedematous, erythematous-vesicular or erythematous-pustular, especially on the eyelids where, often misdiagnosed for a long time, they are treated with topical steroids. This leads to suppression of the phlogosis and the typical morphological characteristics of the mycosis (tinea incognito).

Tinea capitis

Two forms are distinguished: microsporic and tricophytic.

Microsporic tinea is caused by zoophilic fungi. The pathogen most often to blame is Microsporum canis. It is common in children and contagion is from domestic pets or stray animals (cats). Person-to-person contagion is rare. Clinically, it presents with roundish erythematous-squamous patches a few centimetres in diameter, which are usually few in number. The surface of the patches is covered with thin, greyish-white pityriasis scales and parasitised hairs break at 3-4 mm from the follicular orifice.
Trichophytic tinea is caused by anthropophilic fungi. The pathogens most commonly to blame are T. tonsurans, T. soudanense, T. violaceum. This form favours subjects of black ethnicity and affects children from 3 to 8 years of age. Transmission is human-to-human and there may be asymptomatic carriers. It presents with round alopecic patches, usually small and multiple. The broken hairs near the follicular ostia look like black dots, incorporated in greyish-white scales.

Both forms may evolve into a granulomatous infiltrative form called kerion celsi. The predominant location of infection is the scalp where it presents with an alopecic plaque raised on the skin, generally large, with pustules and crusts on the surface and soft to the touch. There may also be lymphadenopathy and fever.

Diagnosis

In addition to patient history, dermoscopy is useful for confirming the clinical suspicion, but the gold standard for diagnosis is direct microscopic examination. A culture test enables the responsible pathogen to be isolated.

Treatment

Oral antimycotics (griseofulvin, terbinafine, fluconazole) are used on tinea of the glabrous skin in the case of multiple lesions and on tinea capitis. To treat tinea of the glabrous skin, if there is one or only a few lesions, topical antimycotics such as imidazole and allylamine are used. Treatment is continued for 10-15 days until complete resolution is obtained. In cases of doubt, after treatment has been suspended for 1 week, a direct microscopic examination may be repeated. In tinea capitis systemic treatment is administered for 4-6 weeks and at all events until full recovery. It is combined with topical antimycotics and the use of shampoos containing antimycotics such as selenium disulphide or ketoconazole is suggested to reduce the spread of spores. Other infected members of the family should be investigated, and if contagion is from a pet, this too must be treated to avoid the risk of reinfection as no immunity develops.

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