Kerion Celsi due to Trichophyton soudanense and Pityriasis rosea following treatment by terbinafine

Abstract

Kerion Celsi is a suppurative-abscessive fungal infection of the scalp. In Europe, it is predominantly caused by zoophilic dermatophytes. In addition to Trichophyton (T.) mentagrophytes, these include T. benhamiae, T. quinckeanum and T. verrucosum [1]. However, anthropophilic pathogens of tinea capitis are on the rise. Dermatophytes that often originate from Africa, such as T. violaceum, T. soudanense and Microsporum (M.) audouinii, usually cause a drier, more scaly and hyperkeratotic form of tinea capitis. A 10-year-old girl developed a pressure-sensitive, painful lesion with hyperkeratosis, pustules, and hair loss in the parting of the head in late summer. Under suspicion of cradle cap, she was treated by a pediatrician with a 0.05 % fluticasone-17-propionate cream. However, the skin lesions on the head continued to worsen. Microbiological diagnostics were not performed. After about three weeks of the painful swelling, in which time pus had also been discharged, the parents presented the girl to the weekend emergency service of a municipal hospital. The child was referred to the pediatric hospital as an inpatient. Upon admission, a circa 3 × 3 × 0.5 cm, purulent abscessed, weeping, circular and raised lesion was seen (Figure 1a). The alopecic area was crusted in the peripheral zone, centrally there were whitish-yellow pustules on a weeping, erythematous base. Application of pressure caused the discharge of pus. Cherry pit-sized lymph nodes were palpable in the neck. No other systemic signs of infection, such as fever, were observed. Two swabs were taken from the weeping pustular area, and some hairs from the peripheral zone were also epilated. To the child, these diagnostics procedures were very distressing due to the pain. Comprehensive bacteriological and mycological diagnostics were performed. Pathogenic bacteria were not detectable. Mycological diagnostics included a fluorescence-optical Blankophor preparation and culturing of the pathogens. Blankophor preparation is considered the fastest and cheapest fungal detection method. The polymerase chain reaction (PCR) in the form of a PCR-ELISA (Enzyme-Linked Immunosorbent Assay) was used for direct molecular biological detection of dermatophyte DNA from both smears and hair roots [2]. PCR for T. interdigitale/ T. mentagrophytes, M. canis and T. benhamiae (according to former nomenclature Trichophyton species of Arthroderma benhamiae) was negative. In contrast, PCR-ELISA yielded a positive test result for T. rubrum DNA already on the following day. However, this dermatophyte is not a plausible cause of tinea capitis in a child. Cross-reactions between T. rubrum and T. violaceum or T. soudanense in PCR-ELISA are known. Therefore, species-specific PCR for T. violaceum was performed, which was negative. Through additional DNA sequencing, the causative agent of tinea capitis was ultimately identified as T. soudanense [3]. A 100 % match between the internal-transcribed spacer (ITS) region of the rDNA and reference sequences of T. soudanense in the NCBI database (National Center for Biotechnology Information in Bethesda, Maryland, USA) was obtained. Within four to five days after availability of the positive fluorescence optical preparation and the positive PCR result, a “lawn” of confluent, bright, deep-yellow stained colonies grew on Sabouraud agar with 4 % glucose (Sifin, Berlin) and on DOI: 10.1111/ddg.14413 Kerion Celsi due to Trichophyton soudanense and Pityriasis rosea following treatment by terbinafine Clinical Letter