DISCUSSION
The biopsy results showed numerous fungal elements crowded around deeper aspects of hair follicles and a granulomatous reaction in the surrounding skin.
Normally, dermatophytes (the organisms that cause superficial fungal infections) are incapable of invading deeper tissues, making KOH exam a simple diagnostic method. But with immune suppression, the infection is able to invade deeper structures, making it more difficult to diagnose and treat. In this patient’s case, the use of steroid creams under occlusion (ie, the watch) had suppressed the body’s immune response to the infection.
The terminology used to describe this phenomenon varies according to the severity of infection. Tinea incognito might be used to describe this patient’s case, in which the steroid rendered the condition almost impossible to diagnose visually. With continued use of stronger topical steroids, the degree of inflammation might have been worse, involving deeper, larger nodules instead of faint pink scaling. In such cases, the term Majocchi fungal granuloma is used.
This patient moved his watch to the other arm temporarily and was successfully treated with twice-daily application of topical econazole cream and a two-week course of oral terbinafine (250 mg/d).
TAKE-HOME LEARNING POINTS
- Immunosuppression can make fungal infections more difficult to diagnose and treat.
- Dermatophytes don’t normally invade deeper structures and can usually be detected with a KOH exam of surface skin cells.
- If the patient is immunocompromised, a fungal diagnosis is best confirmed with a punch biopsy, and treatment achieved with a combination of oral and topical antifungal products.
- Mild cases of this kind are termed tinea incognito, while more severe cases are called Majocchi fungal granuloma.