Majocchi's granuloma of the scalp caused by Trichophyton tonsurans in an immunosuppressed adolescent with Crohn's disease: a case report.

INTRODUCTION: Majocchi's granuloma (MG) is a rare invasive dermatophytosis characterised by invasion of hair follicles and perifollicular granulomatous inflammation. Scalp involvement is uncommon, and Trichophyton tonsurans is an unusual aetiological agent of MG. PATIENT CONCERNS AND CLINICAL FINDINGS: A 16-year-old boy with Crohn's disease treated with infliximab and azathioprine developed a painful inflammatory occipital scalp lesion with colliquation, pustulation, and regional lymphadenopathy shortly after a haircut-related injury. DIAGNOSTIC ASSESSMENT: Initial antibacterial and antiviral therapy was ineffective. Dermatological assessment suggested an unusually severe tinea capitis/kerion-like presentation. Biopsy showed periodic acid-Schiff-positive fungal elements in the dermis with granulomatous suppurative inflammation. Culture yielded a weakly growing dermatophyte consistent with Trichophyton sp. Bidirectional sequencing of the ITS2 region showed 100% similarity to members of the Trichophyton mentagrophytes series and did not discriminate between T. tonsurans and Trichophyton equinum; T. tonsurans was considered the most likely species based on the combined clinical and epidemiological context. THERAPEUTIC INTERVENTION AND OUTCOMES: Terbinafine 250 mg once daily failed to control disease progression. The patient improved after switching to itraconazole 200 mg twice daily, combined with repeated surgical debridement, topical antifungal treatment, and temporary interruption of immunosuppression. The lesion healed completely and hair regrowth was restored. CONCLUSION: This case highlights the need for early microbiological and histopathological assessment of severe scalp lesions in immunosuppressed patients, especially after skin-barrier disruption. It also raises awareness of possible dermatophyte transmission related to hairdressing and of a lack of clinical response to terbinafine in dermatophyte infections.