Exotic mushrooms

Paediatric dermatology

Dr. Emmanuelle Bourrat

Saint-Louis Hospital

The clinical case
Now it's your turn!
Co-prescription and advice

Clinical case presentation

A 9-year-old girl, born in France, having spent two periods in Bangladesh, had been suffering for 1 year from pruritic erythematosquamous plaques initially located in the popliteal fossae, then extending secondarily to the buttocks and thighs. She intermittently applied topical corticosteroids, which relieved the pruritus. There was no contact with animals and no family history of contagion.

There was inflammatory enhancement around the periphery of the plaques and a few pustules, and no involvement of the scalp, nails or mucous membranes. The rest of the somatic examination was unremarkable. The semiology being highly suggestive of dermatophytosis of glabrous skin, a mycological sample was taken, topical corticosteroids were stopped and topical antifungal treatment with bifonazole was prescribed. It was reviewed 4 weeks later, but despite good compliance the dermatosis had barely improved, with persistent infiltrated lesions with an active border.

Your turn

What is your diagnosis?

Select 1 answer(s) from the following choices:

Erythema gyratum repens

Circinate dermatophytosis of glabrous skin caused by Trichophyton mentagrophytes type VIII (T. indotineae), resistant strain

Subacute lupus

Chromoblastomycosis

Wrong answer!

Good answer!

Selected diagnosis

Direct examination of the skin sample was positive (mycelia filaments), as was culture (Trichophyton mentagrophytes).

The extensive nature of this circinate dermatophytosis of glabrous skin, the lack of efficacy of topical imidazole and the fact that the patient had spent time in Bangladesh raised the possibility of a recently described resistant strain from the Indian subcontinent.

A study of the strain's resistance profile and its genotypic characterization confirmed that it was Trichophyton mentagrophytes type VIII, also known as T. indotineae, characterized by clinical resistance to both topical and systemic antifungal agents, including terbinafine at the standard dose of 250 mg/day, which is usually effective against Trichophyton species, and itraconazole.

Explanation of wrong answers

Erythema gyratum repens is a rare migratory, figurate dermatosis of adults, almost always paraneoplastic. This pruritic dermatosis predominates on the trunk in the form of serpiginous, erythematous-squamous bands arranged in parallel, creating a “wood-grain” appearance.
Subacute lupus, associated with anti-Ro antibodies, is characterized by strong photosensitivity and polycyclic annular plaques, with sometimes vesiculocrusted borders.
Chromoblastomycosis is a chronic, extensive, granulomatous fungal infection of the skin caused by dematiaceous fungi. Inoculation occurs following trauma, most often to the lower limbs in subtropical zones. It begins as a psoriasiform plaque or nodule, then progressively becomes verrucous and spreads over the surface but without assuming an annular pattern.

Treatment

There are no treatment recommendations for this new strain, which is fortunately still very rare, but sporadic cases have recently been reported in several European countries.

In the first instance, it is proposed to increase the dosage and duration of systemic antifungal treatment (terbinafine or itraconazole) and above all to detect any family cases and monitor them over the long term, as late relapses have also been described.

Message from the expert

Resistant dermatophytosis caused by Trichophyton indotineae should be considered in the presence of any dermatophyte resistant to topical and systemic antifungal treatment at conventional doses, especially in adult or pediatric patients from Asia.

References

^{Dellière S, Joannard B, Benderdouche M, Mingui A, Gits-Muselli M, Hamane S, Alanio A, Petit A, Gabison G, Bagot M, Bretagne S. Emergence of Difficult-to-Treat Tinea Corporis Caused by Trichophyton mentagrophytes Complex Isolates Emerg Infect Dis. 2022; 28(1):224-228.}