Msk Dermatology · Year 2 · from Msk Dermatology

Case 3: Tinea Capitis

Patient Presentation

Demographics: 7-year-old male

Chief Complaint: Patchy hair loss and scalp itching for 3 weeks

History of Present Illness: The patient's mother noticed areas of hair loss on his scalp 3 weeks ago. The areas have enlarged and become scaly. The child complains of itching. He has a pet cat at home. One classmate at school was recently diagnosed with a similar condition.

Past Medical History:

  • No significant medical history

Physical Examination:

  • Scalp:
  • Multiple circular patches of alopecia
  • "Black dot" appearance (broken hair shafts)
  • Scaling within the patches
  • Mild erythema
  • Posterior cervical lymphadenopathy
  • No involvement of skin elsewhere

Wood Lamp Examination:

  • Blue-green fluorescence in affected areas

Workup and Results

KOH Preparation:

  • Fungal hyphae visible within and around hair shafts (endothrix pattern)

Fungal Culture:

  • Microsporum canis (consistent with cat exposure)

Clinical Image

Clinical photograph showing tinea capitis with circular patches of alopecia, scaling, and the characteristic "black dot" appearance from broken hair shafts at the scalp surface.

Diagnosis

Tinea Capitis - Microsporum canis

Features:

  • Dermatophyte infection of the scalp
  • "Black dot" tinea from broken hair shafts
  • Fluorescence under Wood lamp (Microsporum species)
  • Requires oral antifungal therapy

Discussion

This case illustrates tinea capitis:

  • Oral Antifungal Required: The lecture emphasizes that tinea capitis requires oral antifungal therapy. Topical antifungals cannot penetrate the hair follicle adequately to clear infection.
  • Wood Lamp Fluorescence: The lecture notes that Microsporum species fluoresce under Wood lamp examination. Most Trichophyton species do not fluoresce.
  • KOH Preparation: The lecture identifies KOH preparation as the diagnostic test to identify fungal hyphae. It dissolves keratin and allows visualization of fungal elements.
  • Annular Plaques: The lecture describes the classic appearance of dermatophyte infections (tinea corporis) as annular plaques with central clearing. In tinea capitis, the presentation is more commonly scaling alopecia.

Treatment Plan

  1. Oral Antifungal Therapy:
  • Griseofulvin 20-25 mg/kg/day (microsize) for 6-12 weeks
  • OR Terbinafine for 4-6 weeks (if Trichophyton)
  • Griseofulvin preferred for Microsporum
  1. Adjunctive Therapy:
  • Selenium sulfide or ketoconazole shampoo 2-3 times/week
  • Reduces spore shedding (not sufficient alone)
  1. Prevention of Spread:
  • Do not share combs, brushes, hats
  • Treat household contacts prophylactically
  • Evaluate and treat pet (veterinary referral)
  1. Monitoring:
  • Clinical response in 2-4 weeks
  • Continue treatment until clinical and mycological cure
  • Repeat KOH or culture if no response
  1. School:
  • May return to school once treatment initiated

Teaching Points

  1. Tinea capitis requires oral antifungal therapy (topicals insufficient)
  2. KOH preparation identifies fungal hyphae
  3. Microsporum species fluoresce under Wood lamp (not all dermatophytes do)
  4. Griseofulvin is preferred for Microsporum; terbinafine for Trichophyton
  5. Contact with animals (cats, dogs) is a common source

All cases for this lecture as Markdown