A 10-year-old child presents with patchy alopecia with black dot pattern and fluorescence under Wood's lamp. Culture on Sabouraud's medium grows Microsporum canis. Regarding treatment, the agent of choice and duration are:
- A Topical clotrimazole for 4 weeks
- B Oral itraconazole 3-5 mg/kg/day for 2 weeks
- C Oral fluconazole 6 mg/kg weekly for 3 weeks
- D Oral griseofulvin 15-20 mg/kg/day for 6-12 weeks ✓
Explanation
Tinea capitis caused by Microsporum canis (ectothrix infection, fluoresces yellow-green under Wood's lamp) requires systemic antifungal therapy because the hair follicle cannot be penetrated by topical agents. Griseofulvin remains the drug of choice for tinea capitis in children at 15-20 mg/kg/day of microsize griseofulvin for 6-12 weeks (FDA-approved). Griseofulvin concentrates in keratinized tissues and inhibits microtubule assembly in fungi. Black dot pattern is caused by endothrix infection (Trichophyton tonsurans/T. violaceum) where the hair breaks within the follicle; M. canis is ectothrix but causes broken hair stumps too. Topical agents are adjuncts (antifungal shampoos), not primary treatment.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.