June 2008

An otherwise healthy 3-year-old girl presented with a nine-week history of pruritus and alopecia on a preexisting congenital melanocytic nevus on scalp. Her parents did not recall any external contact agent, and she was not taking any medication. Her past medical record was unremarkable.

Physical examination revealed the presence of a melanocytic congenital nevus on her scalp and forehead with overlying desquamated plaques and subtle erythema (see figures). Most of the hairs in the affected area were broken a few millimeters above the scalp skin surface leading to an alopecia plaque coincident with part of the nevus affected skin. The rest appeared discolored, lusterless and brittle. There were no other abnormalities of the skin. Epiluminiscence revealed a globular pattern with no atypical signs.

What is your diagnosis?

Answer

The differential diagnosis was made between Meyerson’s phenomenon and tinea capitis associated with a melanocytic congenital nevus.

Potassium hydroxide examination of skin scraping and culture of the affected skin revealed the presence of Microsporum canis, leading to the diagnosis of tinea capitis associated with a melanocytic congenital nevus.

Complete clinical resolution was observed with griseofulvin treatment of 300 mg/day.

Discussion

Tinea capitis (also known as ringworm of the scalp) is a disease caused by superficial fungal infection of the skin of the scalp. Clinical presentation of tinea capitis varies from a scaly, noninflamed dermatitis resembling seborrheic dermatitis to an inflammatory disease with scaly erythematous lesions and hair loss or alopecia that may progress to severely inflamed deep abscesses termed kerion, with the potential for scarring and permanent alopecia. The type of symptoms elicited depends on interaction between the host and the etiologic agents.

According to the literature, there has been a significant increase in the incidence of tinea capitis and a change in the pattern of infectious agents, in particular. M. canis, a zoophilic dermatophyte, is still the most common reported causative agent of tinea capitis in Europe. The countries reporting the highest incidence of M. canis infections are mainly in the Mediterranean area. In addition to the increase in Microsporum-induced tinea capitis, there is a shift toward anthrophilic tinea capitis mainly in urban areas in Europe.

The differential diagnosis was made with Meyerson’s phenomenon. Occurrence of halo dermatitis around a melanocytic nevus was first described by Meyerson in 1971. Clinically, these lesions present as melanocytic nevus with associated epidermal scaling and a halo of inflammation. The lesions undergo spontaneous resolution, without regression of the nevus. The Meyerson’s phenomenon is typically described in association with benign acquired nevi, although there are also reports in association with atypical nevi. Published accounts of Meyerson’s phenomenon in association with congenital melanocytic nevi in infants are much less frequent.

Examination of potassium hydroxide preparations determined the proper diagnosis of a tinea infection, providing the culture-precise identification of the species and confirming diagnosis. Only rarely is biopsy necessary.

There is not enough evidence on the use of systemic treatments, such as griseofulvin and terbinafine, in children with Microsporum infections.

The coincidental occurrence of a dermatophytic infection on the surface of melanocytic congenital nevus has not been described previously. Based on the case presented, we would like to remind physicians of this possibility when itchy, melanocytic lesions are found on the scalp.

For more information:

• Elena Sendagorta Cudós, MD, Raul de Lucas Laguna, MD, and Marta Feito Rodríguez, MD, all work in the Department of Dermatology at the University Hospital La Paz, Madrid, Spain.
• Ginter-Hanselmayer G, Weger W, Ilkit M, Smolle J. Epidemiology of tinea capitis in Europe: current state and changing patterns. Mycoses. 2007;50:6-13.
• Hay RJ, Robles W, Midgley G, et al. Tinea capitis in Europe: new perspective on an old problem. J Eur Acad Dermatol Venereol. 2001;15:229-233. /LI>
• Meyerson LB. A peculiar papulosquamous eruption involving pigmented naevi. Arch Dermatol. 1971;103:510-512.
• Kus S, Ince U, Candan I, Gurunluoglu R. Meyerson phenomenon associated with dysplastic compound nevi. J Eur Acad Dermatol Venereol. 2006;20:350-351.
• Tauscher A, Burch JM. Picture of the month-quiz case. Diagnosis: Meyerson phenomenon within a congenital melanocytic nevus. Arch Pediatr Adolesc Med. 2007;161:471-472.
• González U, Seaton T, Bergus G, et al. Systemic antifungal therapy for tinea capitis in children. Cochrane Database Syst Rev. 2007;Oct 17:CD004685.