A Unique Clinicopathological Manifestation of Fungal Infection: A Case Series of Deep Dermatophytosis in Immunosuppressed Patients

Background: Dermatophytes are the most common cause of superficial fungal infections in humans. Deep dermatophytosis, however, is rare, described to date only in isolated case reports, usually in the setting of systemic immunosuppression.

Objective: To present the 15-year experience of a tertiary dermato-mycology clinic with the diagnosis and treatment of deep dermatophytosis.

Methods: Patients were identified by database search. Clinical, mycological, histological, and treatment data were collected from the medical files.

Results: Ten patients were identified: nine after solid-organ transplantation and one undergoing chemotherapy, all diagnosed within 3 years after beginning immunosuppression (average 7.5 months). The infective agent in nine cases was Trichophyton rubrum. All patients presented with concurrent superficial fungal infections. Complete resolution was noted in response to systemic antifungal agents. There was no histological evidence of hair-follicle involvement.

Limitations: The limitations of the study were the retrospective design and the small cohort size.

Conclusion: This case-series study suggests that deep dermatophytosis is a separate entity, distinct from Majocchi's granuloma. It occurs only in immunocompromised patients and is characterized by discrete nodules, an indolent course, the absence of follicular invasion, and proximity to a superficial dermatophyte infection. Systemic antifungal treatment leads to complete resolution. The urgent need for the treatment of superficial fungal infections in immunocompromised patients is emphasized.