Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2023;13(1):e2023037 1 An Unexpected Dermatophyte? Two Remarkable Cases of Tinea Barbae by Trichophyton benhamiae Gloria Baeza-Hernández1, María de la Soledad Vallejo-Ruiz1, Ricardo Francisco Rubio-Aguilera1, Alberto Romero-Maté1, Cristina Martínez-Morán1 1 Dermatology Department, Hospital de Fuenlabrada. Fuenlabrada, Madrid, Spain Key words: Trichophyton benhamiae, Arthroderma benhamiae, tinea barbae, dermatophytosis, terbinafine Citation: Baeza-Hernández G, de la Soledad Vallejo-Ruiz M, Rubio-Aguilera RF, Romero-Maté A, Martínez-Morán C. An Unexpected Dermatophyte? Two Remarkable Cases of Tinea Barbae by Trichophyton benhamiae. Dermatol Pract Concept. 2023;13(1):e2023037. DOI: https://doi.org/10.5826/dpc.1301a37 Accepted: June 13, 2022; Published: January 2023 Copyright: ©2023 Baeza-Hernández et al. This is an open-access article distributed under the terms of the Creative Commons Attribution- NonCommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited. Funding: None. Competing Interests: None. Authorship: All authors have contributed significantly to this publication. Corresponding Author: Gloria Baeza-Hernández, Servicio de Dermatología, Hospital de Fuenlabrada, Camino del Molino 2, 28942 Fuenlabrada, Madrid, Spain. E-mail: gloria.baeza@salud.madrid.org Introduction Trichophyton (T.) benhamiae is considered an emergent zoo- philic dermatophyte, with more cases being reported from various countries around the world. We hereby present two cases of tinea barbae by T. benhamiae. Case Presentation Case 1. A 48-year-old man attended the emergency depart- ment with a 1-month history of facial lesions treated with ci- clopirox and mupirocin ointment. He had a healthy pet dog. On examination, he had extensive impetiginized crusts all over the nasolabial triangle. Removal of the crusts revealed erythematous, vegetating plaques on the nasolabial folds (Figure 1). Case 2. Another 50-year-old man, owner of a healthy dog, came to the outpatient clinic complaining of a two-week facial rash previously treated with topical clobetasol and gentamicin without improvement. On examination he had an erythematous plaque on his chin, with some pustules and erosions covered by serous-hematic crust, and a 2-3 cm nod- ule in the plaque’s border (Figure 2). Some of his closest fam- ily members were being treated for tinea corporis. Scales were gathered for fungal culture. In both cases, T. benhamiae was identified by MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry analysis. Terbinafine 250 mg daily for three months com- pletely cleared the lesions in both patients. Conclusions T. benhamiae, previously known as Arthroderma (A.) ben- hamiae, is nowadays a species on its own according to the latest dermatophyte taxonomy, based on the analysis of the internal transcribed spacer (ITS) ribosomal DNA re- gion [1,2]. Every year, more cases of T. benhamiae are being re- ported worldwide particularly among children. This zoo- philic dermatophyte is mainly transmitted by guinea pigs, 2 Research Letter | Dermatol Pract Concept. 2023;13(1):e2023037 and seldom by other infected animals like rabbits, cats, dogs and even a fox [3]. Our patients were both adults and only had contact with their pet dogs, which were apparently unaffected; however, we have no information about their veterinary evaluation. Retrospectively our patients couldn’t remember being near a guinea pig, which can be silent car- riers of T.  benhamiae [4]. We haven’t found studies about T. benhamiae colonization in dogs. Clinically, it usually causes highly inflammatory tinea corporis and faciei which can be confused with impetigo, delaying a correct diagnosis [5]. There are scattered reports of kerion celsi and onychomycosis [3,5]. To the best of our knowledge, only one case of tinea barbae by T. benham- iae has been previously reported by Braun et al in 2013, a 24-year-old male in which the authors identified A. benham- iae by PCR in the patient and in his guinea pig [6]. Identification of T. benhamiae requires molecular meth- ods due to its similarity to other fungal species in standard cultures. Yellow subtype of this fungus grows in colonies that may be diagnosed as Microsporum canis, and the un- usual white subtype is usually identified as T. mentagro- phytes. Polymerase chain reaction (PCR) of the ITS region and MALDI-TOF both allow for a correct diagnosis [7]. Treatment is akin to that of other dermatophyte infec- tions. If the infection covers an extensive area or hair follicles are affected, oral treatment is preferred, terbinafine being the first choice [3,5]. Tinea barbae by T. benhamiae seems to be rare. Previ- ous contact with animals, especially guinea pigs, and inflam- matory lesions on physical examination should prompt the diagnosis of T. benhamiae infection. Molecular diagnostic methods like PCR and MALDI-TOF are necessary to ensure correct identification of this emergent dermatophyte. References 1. Shiraki Y, Hiruma M, Matsuba Y, et al. A case of tinea cor- poris caused by Arthroderma benhamiae (teleomorph of Tinea mentagrophytes) in a pet shop employee. J Am Acad Dermatol. 2006;55(1):153-154. DOI:10.1016/j.jaad.2005.05.048. PMID: 16781312. 2. de Hoog GS, Dukik K, Monod M, et al. Toward a Novel Multilocus Phylogenetic Taxonomy for the Dermatophytes. Mycopathologia. 2017;182(1-2):5-31. DOI:10.1007/s11046- 016-0073-9. PMID: 27783317. PMCID: PMC5283515. 3. Tan J, Liu X, Gao Z, Yang H, Yang L, Wen H. A case of Tinea Faciei caused by Trichophyton benhamiae: First report in China. BMC Infect Dis. 2020;20(1):1-5. DOI:10.1186/s12879-020- 4897-z. PMID: 32087692. PMCID: PMC7036192. 4. Berlin M, Kupsch C, Ritter L, Stoelcker B, Heusinger A, Gräser Y. German-wide analysis of the prevalence and the propagation factors of the zoonotic dermatophyte trichophyton benham- iae. J Fungi. 2020;6(3):1-11. DOI:10.3390/jof6030161. PMID: 32899171. PMCID: PMC7558194. 5. Nenoff P, Uhrlaß S, Krüger C, et al. T Trichophyton species of Arthroderma benhamiae - a new infectious agent in dermatol- ogy.  J Dtsch Dermatol Ges. 2014;12(7):571-581. DOI:10.1111 /ddg.12390. PMID: 24981469. 6. Braun SA, Jahn K, Westermann A, Bruch-Gerharz D, Reifen- berger J. Tinea barbae profunda durch Arthroderma benhamiae. Der Hautarzt. 2013;64(10):720-722. DOI:10.1007/s00105-013- 2646-6. PMID: 24150818. 7. Sabou M, Denis J, Boulanger N, et al. Molecular identification of Trichophyton benhamiae in Strasbourg, France: A 9-year retro- spective study. Med Mycol. 2018;56(6):723-734. DOI:10.1093 /mmy/myx100.  PMID: 29165673. Figure 1. Case 1: clinical image of tinea barbae caused by Tricho- phyton benhamiae. Erythematous vegetating plaques on the nasola- bial folds, devoid of hair in some areas. Figure 2. Case 2: clinical picture of tinea barbae caused by Tricho- phyton benhamiae. Erythematous plaques in the chin and right cheek, with erosions and pustules, with a 2-3 cm nodule in the chin plaque border.