Geophilic Tinea Profunda after a Stay at a Swiss Lake: A Cas
A 53-year-old female patient presented with a slightly red, partially hypopigmented, pruritic scaly plaque with recurrent pustules on her right upper arm in September 2019.

The onset of this new, initially bright red lesion was about 2 months prior to the first consultation. She described first skin signs developing a few days after a mosquito bite during a visit to a public swimming area at a local lake, where she also had been swimming. No other triggers such as gardening, pets, or travel were identified.

Her family doctor suspected eczema and prescribed therapy with topical clobetasol for more than 6 weeks. According to the patient, the lesion became more intensely erythematous but was less symptomatic during this therapy with topical corticosteroids. However, there was no effect on the size of the plaque nor the development of new pustules.

On her first visit to clinic, they took a deep skin biopsy for histological and polymerase chain reaction (PCR) analysis (fungus, mycobacteria). Histology showed a deep inflammatory infiltrate mainly consisting of neutrophil granulocytes; there was no granuloma formation nor any positivity in PAS staining. A few days later, PCR analysis revealed growth of Nannizzia gypsea. This geophilic fungus is often isolated in soil or sand, can rarely cause intensely inflammatory ringworm lesions (like in our patient), and is more often seen in women. The analysis for mycobacteria remained negative.

The patient was then treated with oral itraconazole 100 mg daily for 14 days. Topically she applied a ciclopirox cream twice a day.

Two weeks after completing this treatment, the original plaque presented slightly hypopigmented without any redness, scaling, or pustules.

In a follow-up consultation 2 months later, all skin manifestations had almost completely disappeared, except for a minimal central atrophy.