Dermal Infection with Trichophyton rubrum in an Immunocompetent Patient

Erythematous Plaque Studded With Papules and Pustules in an Immunocompetent Patient

A male patient was evaluated by the dermatology inpatient consult service after a 5-week history of a skin lesion on the right anterior thigh with intermittent itching and mild tenderness to palpation. What is your diagnosis?

Deep-seated dermatophytosis caused by Trichophyton rubrum in patient with Becker muscular dystrophy

Trichophyton rubrum is a common fungal pathogen that usually causes superficial infection limited to epidermis only, so called dermatophytosis. However in immunocompromised patients, dermatophytosis can be exceptionally more invasive with extensive lesions involving deep tissues and generating sometimes systemic course. We report the case of a 43-year-old heart transplanted man, who presented with multiple deep-seated nodules and papules in the inguinal areas and in the buttocks. Involvement of Trichophyton rubrum was confirmed by culture, DNA sequencing and histological examination that showed granulomatous inflammatory infiltrates with the presence of hyphae in the dermis. Antifungal therapy with oral terbinafine for four weeks was successful; in spite of initial remnant atrophic scars, the lesions were completely cleared after four month evolution. Deep-seated invasive dermatophytosis is rare, but should be considered with immunocompromised conditions, especially when history of previous superficial dermatophytosis is present.

Epidemiology and Diagnostic Perspectives of Dermatophytoses

Dermatophytoses affect about 25% of the world population, and the filamentous fungus Trichophyton rubrum is the main causative agent of this group of diseases. Dermatomycoses are caused by pathogenic fungi that generally trigger superficial infections and that feed on keratinized substrates such as skin, hair, and nails. However, there are an increasing number of reports describing dermatophytes that invade deep layers such as the dermis and hypodermis and that can cause deep infections in diabetic and immunocompromised patients, as well as in individuals with immunodeficiency. Despite the high incidence and importance of dermatophytes in clinical mycology, the diagnosis of this type of infection is not always accurate. The conventional methods most commonly used for mycological diagnosis are based on the identification of microbiological and biochemical features. However, in view of the limitations of these conventional methods, molecular diagnostic techniques are increasingly being used because of their higher sensitivity, specificity and rapidity and have become more accessible. The most widely used molecular techniques are conventional PCR, quantitative PCR, multiplex PCR, nested, PCR, PCR-RFLP, and PCR-ELISA. Another promising technique for the identification of microorganisms is the analysis of protein profiles by MALDI-TOF MS. Molecular techniques are promising but it is necessary to improve the quality and availability of the information in genomic and proteomic databases in order to streamline the use of bioinformatics in the identification of dermatophytes of clinical interest.