Scrapings of the child’s rash were analyzed with potassium hydroxide (KOH) under microscopy which revealed multiple septate hyphae.
She was diagnosed with Majocchi’s granuloma. The fungal culture was positive for Trichophyton rubrum.
Majocchi’s granuloma (MG) is cutaneous mycosis in which the fungal infection goes deeper into the hair follicle causing granulomatous folliculitis and perifolliculitis.1 It was first described by Domenico Majocchi in 1883, and he named the condition “granuloma tricofitico.”2
It is commonly caused by T. rubrum but also can be caused by T. mentagrophytes, T. tonsurans, T. verrucosum, Microsporum canis, and Epidermophyton floccosum.2,3 Patients at risk for developing this infection include those previously treated with topical corticosteroids, immunosuppressed patients, patients with areas under occlusion, and those with areas traumatized by shaving. This infection is most commonly seen in the lower extremities, but can happen anywhere in the body. The lesions present as deep erythematous papules, pustules, and may form an annular or circular plaque as seen on our patient.
A KOH test of skin scrapings and hair extractions often can reveal fungal hyphae. Identification of the pathogen can be performed with culture or polymerase chain reaction of skin samples. If the diagnosis is uncertain or the KOH is negative, a skin biopsy can be performed. Histopathologic examination reveals perifollicular granulomas with associated dermal abscesses. Giant cells may be observed. MG is associated with chronic inflammation with lymphocytes, macrophages, epithelioid cells, and scattered multinucleated giant cells.2,3
Dr. Catalina Matiz
The differential diagnosis for these lesions in children includes other granulomatous conditions such as granulomatous rosacea, sarcoidosis, and granuloma faciale, as well as bacterial or atypical mycobacterial infections, cutaneous leishmaniasis, and eosinophilic pustular folliculitis.
Treatment of MG requires systemic treatment with griseofulvin, itraconazole, or terbinafine for at least 4-8 weeks or until all the lesions have resolved. Our patient was treated with 6 weeks of high-dose griseofulvin with resolution of her lesions.
Dr. Matiz is a pediatric dermatologist at Southern California Permanente Medical Group, San Diego. She said she had no relevant financial disclosures. Email her at pdnews@mdedge.com.
References
1. Dermatol Online J. 2018 Dec 15;24(12):13030/qt89k4t6wj.