A high school wrestler developed a rash on his forearm. The rash was erythematous, raised, mildly pruritic, and had diffuse, dry scale. A physician visually diagnosed the rash as eczema. The topical steroid triamcinolone 0.1% cream was prescribed, with instructions to apply twice daily until clear. The rash increased in size over 1 month, despite treatment. The rash at the 1 month follow-up had less scale, no pruritus, and had developed a shiny, firm appearance (Fig. 1). The wrestler was referred to dermatology, where a punch biopsy of the lesion and culture were obtained. Light microscopy demonstrated features of an inflammatory folliculitis, and Periodic acid-Schiff staining highlighted fungal elements within the surface cornified layer and the follicular lumen. Majocchi's granuloma was diagnosed. Extracted hair shafts grew Trichophyton tonsurans on fungal culture. Antifungal therapy with oral terbinafine 250 mg daily was started. The rash resolved after 3 months of treatment.
Majocchi's granuloma is a fungal folliculitis that commonly develops when a dermatophyte infection presenting with an erythematous, raised rash with scale is presumed to be eczema and is empirically treated with topical steroids. In this situation, the topical steroid suppresses cell-mediated clearing of dermatophyte on the skin surface. Organisms then extend down into hair follicle ostia, causing a deep folliculitis with an exuberant inflammatory response, which includes granulomatous inflammation. Once this is established, a biopsy may be required for diagnosis. Topical antifungal treatment does not penetrate into deep follicular structures, thus, systemic antifungal therapy may be required. Accurate initial diagnosis and initial treatment with topical antifungal therapy may prevent this condition from developing.
Diagnostic testing options for an erythematous, raised rash with scale at initial presentation include potassium hydroxide (KOH) light or fluorescence microscopy, culture, and polymerase chain reaction for identifying dermatophytes. Surface sampling of scale at the periphery of lesions provides material for analysis. Ovren et al. reported on a clinical dermatologist with more than 30 years of weekly microscopy experience. On 206 untreated samples, the dermatologist's KOH light microscopy readings had 62% sensitivity and 94% specificity compared with culture results (1). Utilizing fluorescent microscopy improved sensitivity to 76%, with a specificity of 92%. On the same samples, a previously inexperienced medical student given 2 h of training had 59% sensitivity, 92% specificity with light microscopy, and 71% sensitivity, 92% specificity with fluorescent microscopy.
In our case, the rash had already been treated with a month of topical steroid cream. KOH microscopy results on surface samples in Majocchi's has not been reported but is presumed to be much less sensitive than on initial presentation. KOH microscopy has been reported on extracted hair shafts (2). In the majority of patients (76.7%), the KOH examination was positive. However, in some Majocchi’s granuloma cases (23.3%), KOH preparations of scales and pustules may reveal no hyphal structures (3).
Majocchi's granuloma is mostly not only caused by dermatophytes but also can be caused by other molds that may require treatment with particular antimycotic agents. Therefore, an unambiguous identification of the fungus is mandatory, especially in immunocompromised patients (2). The pathogen must be identified by culture (3). The most common dermatophyte species that cause Majocchi's granuloma in both immunocompetent and immunosuppressed individuals is Trichophyton rubrum. Additionally, T. rubrum is the most common fungal cause worldwide of both acute and chronic cutaneous and nail dermatophytosis. Other causative agents include T. rubrum with the raubitschekii morphotype, Trichophyton mentagrophytes, T. tonsurans, T. verrucosum, Microsporum canis, and Epidermophyton floccosum (2).
Systemic antifungals, such as griseofulvin, ketoconazole, itraconazole, and terbinafine, are the mainstays of therapy because they are safe and effective (2). The duration of therapy should be at least 4 to 8 wk, and treatment should be continued until all lesions have cleared. The case we are reporting took a total of 12 wk to clear.
Utilizing KOH microscopy poses several logistical challenges. KOH microscopy requires both a microscope and a trained eye to identify the dermatophyte. A total of US $5.83 is the reimbursement listed in the Centers for Medicare & Medicaid Services (CMS) 2018 Clinical Laboratory Fee Schedule (4). KOH microscopy has been classified as one of the “top 10 forgotten diagnostic procedures” (5). We searched the CMS national summary data and found that 43% less KOH microscopy tests were performed and billed to Medicare in 2015 compared with 2001 (6) (see Fig. 2).
Once relatively rare, Majocchi's granuloma has been recently described in another wrestler (7). The incidence of Majocchi's granuloma may be increasing due to decreased use of diagnostic KOH microscopy testing.
Clinicians should consider Majocchi's granuloma and perform KOH microscopy and culture on extracted hairs in rashes that have been visually diagnosed as eczema but are not improving with empirical steroid treatment. Punch biopsy should be considered as well. Accurate initial diagnosis and treatment of erythematous, raised rash with scale may prevent this complication. KOH microscopy is relatively inexpensive, but requires specialized equipment, sample preparation, and training in determining the result. These key components are often not available in high school athletic training rooms and convenient care clinics. Newer diagnostic methods for dermatophyte skin infections or improved KOH microscopy training and reimbursement may help prevent the development of Majocchi's granuloma.
The authors declare no conflict of interest and do not have any financial disclosures.
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