Leyao Shi,1,* Juanjuan Li,2,* Weida Liu,3 Dongmei Shi4,5 

1The Second Clinical Medical College, Shandong University of Traditional Chinese Medicine, Jinan, Shandong, People’s Republic of China; 2Department of First Clinical Medical College, Xuzhou Medical University, Xuzhou, Jiangsu Province, 221004, People’s Republic of China; 3Department of Medical Mycology, Institute of Dermatology, Chinese Academy of Medical Science and Peking Union Medical College, Nanjing, 210042, People’s Republic of China; 4Department of Dermatology, Jining No. 1 People’s Hospital, Jining, Shandong, 272067, People’s Republic of China; 5Laboratory of Medical Mycology, Jining No. 1 People’s Hospital, Jining, Shandong, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Dongmei Shi, Department of Dermatology, Jining No. 1 People’s Hospital, No. 6 Jiankang Road, Jining, Shandong Province, 272000, People’s Republic of China, Tel +86 537-6051008, Email shidongmei28@163.com

Abstract: Tinea capitis, primarily caused by dermatophytes such as Trichophyton and Microsporum species, is a superficial fungal infection affecting the scalp and hair, commonly observed in prepubertal children but rare in adults. Here we report a unique case of an adult female with tinea capitis presenting as diffused alopecia and erythema inflammation on the scalp’s apex, mimicking seborrheic dermatitis. Examination of the hair and scalp using fluorescence microscopy and fungal culture identified the presence of hyphae from Malassezia globosa, Malassezia furfur and Microsporum canis. The patient underwent with oral antifungal treatment for 3 months, resulting in the resolution of the rash and subsequent hair regrowth, with no recurrence during 6-month follow-up. In vitro co-culture experiments of Microsporum canis and Malassezia (both Malassezia globose and Malassezia furfur) revealed that Malassezia appears to facilitate Microsporum canis growth, while the reverse was not observed. This data suggests that Malassezia’s use of long-chain fatty acids by might reduce its antibacterial effect, potentially aiding adult tinea capitis development caused by Microsporum canis.

Keywords: Microsporum canis, Malassezia, tinea capitis, coinfection