Tinea capitis. A 2 × 3 cm oval patch of alopecia with short hair ends and black dots
Clinical Differential Diagnosis
The physical examination and clinical history is most consistent with tinea capitis. However, other diagnostic possibilities include alopecia areata, seborrheic dermatitis, and atopic dermatitis. A complete differential diagnosis of tinea capitis also includes psoriasis, trichotillomania, systemic lupus erythematosus, pityriasis amiantacea, and folliculitis. It is imperative to distinguish tinea capitis from other possible superficial fungal infections caused by Candida spp and Malassezia spp.
Fungal culture to determine the causative organism is preferred but biopsy may be performed in unclear cases. Dermatophytes are hyaline fungi requiring GMS or PAS stain for adequate visualization in H&E preparations. Dermatophytes as branched, septate hyphae and/or spores are seen. Kerions might demonstrate a brisk neutrophilic infiltrate or Majocci’s granuloma formation (follicular involvement of the fungal organism) (Guarner & Brandt 2011).
Lesion scrapings were obtained, prepped with potassium hydroxide (KOH), and viewed under the light microscope, revealing branching hyphae. A fungal culture of involved hair was performed in order to identify the causative organism.
The diagnosis of tinea capitis, as well as the nature of this fungal infection, was discussed with the patient and family. Treatment options were reviewed including the need for oral antifungal medication as topical medications are often ineffective. The patient was immediately started on micronized griseofulvin 25 mg/kg daily for 8 weeks while cultures were pending. Topical antifungal shampoo with selenium sulfide was prescribed for the patient and close contacts to use. Precautions to rid fomites (hair brushes, pillowcases, and sheets) of fungal spores were discussed to prevent spread and reinfection. Possible sequelae of tinea capitis, including persistent alopecia and post-inflammatory dyspigmentation were discussed although they are rare. The patient was given a follow up appointment in 2 months to assess for resolution of symptoms. Parents were told to come into clinic if symptoms worsen or if features of superimposed infection occur.
Tinea capitis, commonly known as scalp ringworm, is a common cutaneous dermatophyte fungal infection of the scalp and hair follicles most commonly affecting children, especially of African American and Hispanic descent. Tinea capitis has a prevalence of 13 % in US school children (Silverberg et al. 2002). Rates continue to increase in African American children. Risk for tinea capitis is increased in crowded living conditions. Adults can be carriers of the pathogens in the scalp with African American women in particular having the most reported adult cases of tinea capitis (Silverberg et al. 2002).
Trichophyton tonsurans is the most common pathogen causing tinea capitis in the United States. Other species include Microsporum spp, including Microsporum canis which is the most common worldwide pathogen. Human to human spread occurs most frequently but animals and plants can be reservoirs for dermatophytes. The method of spread depends on the type of fungal pathogen.
Signs of tinea capitis include: hair loss with broken hairs or black dots on the scalp, scaling, erythema, edematous boggy plaques often studded with pustules called kerions, tenderness, and scarring. Cervical lymphadenopathy may occur as well as low-grade fevers. There can also be associated pruritus of the affected scalp. Significant seborrheic dermatitis is less common in children; the presence of scaling in a child should trigger examination for tinea capitis. In Caucasian children, scalp hyperkeratosis of childhood is most often associated with atopic and seborrheic dermatitis, however research has shown that in African American and Hispanic children hyperkeratosis of childhood is most often associated with tinea capitis (Coley et al. 2011).