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Tinea capitis is defined as an infection of hair follicles on scalp and surrounding skin, and commonly caused by dermatophyte fungi[1]. Tinea capitis remains a significant global public health concern in urban areas, and usually infects children aged from 3 to 7 years, but rarely affect adults and infants[2]. The genera Microsporum and Trichophyton are the predominant pathogens of this disease[1]. In Europe and other developed countries, the incidence of tinea capitis has substantially increased recently[1]. According to a retrospective study[3], Microsporum canis (M. Canis) has been remaining the dominant pathogen for tinea capitis among children in China between 2000 and 2010. However, the anthropophilic dermatophyte species-Trichophyton violaceum (T. violaceum) was prevalent in the eastern China and therefore kerion celsi ranked as the second frequent agent of tinea capitis (12.73% in 7,684 cases)[3]. Now, we report a case of kerion celsi caused by T. violaceum and retrospectively analyze kerion celsi reported in China from 2011 to 2018.
A 6-year-old, formerly healthy girl was admitted with a 14-day history of multiple pustules on the scalp and the lesions progressed from pustules to abscesses and weeping (Figure 1A). She had been treated with systemic antibiotics and topical Traditional Chinese Medicine lotion against bacterial infection for one week. The lesions had no response, and the affected area expanded rapidly, accompanying with obvious swelling, itching, boggy, tender mass and pus with peculiar smell. She had no fever and other discomfort. According to her mother’s description, she rarely contacted with animals, and their living environment met the basic hygiene needs.
Physical examination revealed that the top of the scalp was covered by multiple erythema papules, papulovesicles and tender mass. The hairs on the affected area were either loss or broken, overlying with yellow medicine scabs. It tended to be pain when pressed the tender mass. The girl was otherwise in good condition.
Laboratory tests showed that white blood cells were 14.35 × 109/L (neutrophils counting for 10.25 × 109/L) and IgG was 38 g/L. No bacterial infection was found, but a direct 10% potassium hydroxide (KOH) examination of pus was positive. Fungal culture (Figure 1E and Figure 1F). The histopathological results (Figure 1G and Figure 1H) revealed a mild thickening of the epidermis, edema of intercellular prickle cell and dense cell infiltration around hair follicles, which mainly included eosinocytes, and a few of lymphocytes, plasmocytes, histiocytes, and neutrophils using skin specimens. Periodic Acid-Schiff (PAS) staining revealed hyphae and spores surrounded the hair follicle and spores accumulated within the hair shaft (Figure 1I). Diagnosis of T. violaceum infection was confirmed by fungal culture and pathological examination.
The patient was orally treated with 125 mg/d terbinafine, 4 mg/d triamcinolone and 0.3 g/d roxithromycin. In addition, naftifine hydrochloride and ketoconazole cream and ketoconazole lotion were topically used for scalp lesions. Meanwhile, the patient was instructed to have a haircut weekly. After 1 week of treatment, the erythema, swellings and pain were mostly relieved. The cortisone and antibiotic were then withdrawn, but oral terbinafine at same dosage was continuing for additional 7 weeks until the pustule disappeared and hairs growth became visible. By the end of 8 weeks’ antifungal therapy, the erythema was still somewhat visible (Figure 1B), which gradually reduced with another 4 weeks’ antifungal treatment (Figure 1C). The new hairs regrew and no scar was seen in a follow-up visit (Figure 1D).
A retrospective analysis of kerion celsi in China was performed in PubMed, CNKI, WeiPu, WanFang databases to include literature published in Chinese or English between January, 2011 to July, 2018 using "tinea capitis" or "kerion" as searching words in the titles or abstract of publication. The inclusion criteria are as follows: 1) investigations were enforced in China; 2) articles included the words "tinea capitis" , "superficial fungal" ; 3) articles included the words "kerion celsi" , or "kerion" ; 4) definite diagnosis with clinical type and evidence of fungal species; 5) the sample size was more than 30 cases. The publications of repeated or overlapped data were removed.
A total of 9 articles involving 2,990 tinea capitis cases were selected, of which 500 patients were diagnosed as kerion celsi by fungal culture and clinical features (Table 1)[4,5,6,7,8,9,10,11,12]. All the studies were done in Chinese. Compared with the average incidence rate of 16.72% (500/2,990), kerion celsi remained the highest (up to 29.31%) in Jiangxi Province. The predominant causative agents were T. mentagrophytes (26.2%), followed by M. canis (22.22%), T. violaceum (20.8%), T. rubrum 9.40%), T. tousurans (8.40%), M. gypseum (8.2%) and T. verrucosum (4.20%). Geophilic dermatophytes were rare as expected, and only three patients were reported. Two were caused by M. fulvum and another was infected by M. ferrugineum (Table 2). Compared with a retrospective analysis of tinea capitis children in China between 2000 and 2010[3], the most obvious change is that the ratio of kerion celsi caused by T. violaceum has doubled from 9.75% to 20.8%, while the rating of M. canis has fallen from 37.87% to 22.2% (Table 2).
Pathogen distributions of kerion celsi between 2011 and 2018
Pathogen distributions of kerion celsi between 2011 and 2018
| References | Year of data | Area | T.vi | T.r | M.fe | T.t | M.c | T.m | T.v | M. g | M.fu | Total | Frequency(%) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Zhu et al.4 | 1993-2011 | Shanghai | 21 | 15 | 0 | 7 | 29 | 19 | 0 | 4 | 0 | 95 | 11.30 |
| Li et al.5 | 2010 | Jiangxi | 2 | 6 | 0 | 5 | 0 | 15 | 0 | 0 | 0 | 28 | 23.93 |
| Sun et al.6 | 2008-2011 | Jiangxi | 0 | 3 | 0 | 0 | 6 | 1 | 0 | 16 | 2 | 28 | 15.30 |
| Hu et al.7 | 2000-2011 | Hubei | 62 | 6 | 1 | 26 | 46 | 43 | 0 | 17 | 0 | 201 | 22.41 |
| A et al.8 | 2011-2012 | Xinjiang | 0 | 0 | 0 | 0 | 23 | 0 | 20 | 0 | 0 | 43 | 25.40 |
| Gao et al.9 | 2006-2013 | Jiangsu | 0 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 4 | 12.12 |
| Li et al.10 | 2013-2014 | Jiangxi | 2 | 4 | 0 | 0 | 3 | 18 | 0 | 3 | 0 | 30 | 29.31 |
| Li et al.11 | 2004-2015 | Hubei | 11 | 11 | 0 | 0 | 1 | 7 | 1 | 0 | 0 | 31 | 24.41 |
| Yu et al.12 | 2011-2015 | Hubei | 6 | 1 | 0 | 3 | 2 | 27 | 0 | 1 | 0 | 40 | 14.45 |
| Total | 104 | 47 | 1 | 42 | 111 | 131 | 21 | 41 | 2 | 500 |
The total numbers of kerion celsi cases in two decades and the frequency of dermatophytes isolated
The total numbers of kerion celsi cases in two decades and the frequency of dermatophytes isolated
| References | Year of data | Area | T.vi | T.r | M.fe | T.t | M.c | T.m | T.v | M. g | M.fu | Total | Frequency(%) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Li et al.3 | 2000-2010 | China | 43 | 47 | 0 | 19 | 167 | 94 | 1 | 65 | 0 | 441 | 12.73 |
| (9.75) | (10.66) | - | (4.31) | (37.87) | (21.32) | (0.23) | (14.74) | - | |||||
| Present study | 2011-2018 | China | 104 (20.80) | 47 (9.40) | 1 (0.20) | 42 (8.40) | 111 (22.20) | 131 (26.20) | 21 (4.20) | 41 (8.20) | 2 (0.40) | 500 | 16.72 |
Kerion celsi also known as "kerion" is a special type of tinea capitis, and causes a T-cell-mediated hypersensitivity reaction[13]. The species of fungus cause tinea capitis vary by geographic location, but typically fall into the genera T. mentagrophytes, T. verrucosum, T. rosaceum, T. megninii, T. tonsurans, T. violaceum, and T. soudanense[2].
T. violaceum, an anthropophilic dermatophyte, could produce an intense inflammatory response as the case reported here. It is also a common agent to cause tinea corporis, tinea facial, tinea pedis, and endothrix type of hair infection. T. violaceum is a popular genus of tinea capitis in China and other countries[2,14]. A 16-year survey of tinea capitis in Southeastern China found that T. violaceum is the second contributor of kerion celsi, acounting for 26.87%, and the first of Endothrix kerion[14]. Kerion celsi trends to present with various clinical manifestations due to the different immune responses of hosts, especially in the patients who have experienced with irregular antifungal treatment. Therefore, it is easy to be misdiagnosed. Most of initial diagnoses are bacterial infection: for example, bacterial folliculitis, abscesses, follicular impetigo. It is rather unusual for bacterial infections to cause hair loss, and hairs plucked from a bacterial scalp abscess are painful. The main identification point is the pathogenic bacterium. Bacterial folliculitis may be caused by various pathogens, such as Staphylococcus aureus, yeasts and Pseudomonas aeruginosa except dermatophytes[16]. Therefore, it is important to consider tinea capitis in scalp lesions, and a careful medical history and a complete physical examination are crucial to identify a fungal infection.
Without inmediate treatment, patients are easy to have atrophic scar after recovery due to the strong immunoreaction, which may lead to a serious psychological effect. Therefore, once the diagnosis of kerion celsi is made, immediately medical attention is recommended according to the British Association of Dermatologists guidelines for the management of tinea capitis 2014[1]. The treatment program should be based on the most likely fungus before pathogenic agent is determined. Terbinafine is the optimal oral therapy for tinea capitis caused by T. tonsurans, T. violaceum and T. soudanense, while griseofulvin or itraconazole is more powerful for M. canis and M. audouinii. In this study, we report a case of kerion celsi caused by T. violaceum in a child, who was treated successfully with corticosteroids and terbinafine. Regarding to the use of corticosteroids in fungal infection, it is always controversial. In one randomized controlled trial, none additional benefit was found in 30 kerion celsi patients with additional prednisolone[17]. Similarly, a retrospective study supports this finding, in which oral and intralesional glucocorticoids are proven needless for tinea capitis therapy[18]. By the contrast, another study suggested that itraconazole combined with prednisone is more effective than itraconazole alone in randomized controlled trial with 96 children in China[19]. The rationality to introduce prednisone is to suppress the local inflammatory response[18,19]. In our case, the inflammation of the scalp was well controlled after 1 week of glucocorticoid and terbinafine treatment.
Continuing use of antifungal drugs healed the girl completely, and regrowth of hairs without sign of relapse was observed at follow-up visit 4 weeks later.
A retrospective analysis about epidemiology of tinea capitis among children in China between 2000 and 2010 showed that tinea alba was the most frequent clinical pattern (71.16% in 7,684 cases). M. canis was the principle pathogen in most areas (67.99%), followed by T. violaceum (8.51%) and T. mentagrophytes (8.14%). Kerion celsi incidence was 12.73%, in which M. canis (37.87%) and T. violaceum (9.75%) were prevalent agents. Some changes on pathogen spectrum were found in 2011-2018. Our analysis showed that the ratio of kerion celsi caused by T. violaceum rised from 9.75% to 20.8%. T. mentagrophytes became the predominant dermatophyte isolated in 26.2% cases and replaced M. canis as the first cause of kerion celsi.
Only two patients with M. fulvum were isolated in Jiangxi province. This species is a geophilic dermatophyte, which rarely infects human or animals[20]. In fact, M. fulvum can easily be misidentified in most instances.
Anthropophilic dermatophytes used to be the most common cause of tinea capitis over the last century, but current seem to have submitted to zoophilic dermatophytes species[21]. Zoophilic fungi include M. canis, T. verrucosum, and T. mentagrophytes. In our collected data, zoophilic dermatophytes accounted for 59.42% of kerion celsi infections. The change of life model may be the main reason, for example, increasing people tend to keep pets, which no doubt would increase the opportunity of zoophilic dermatophytes infection.
In conclusion, kerion celsi is not a single pathogen causing disease, and can be resulted from different fungal pathogens upon different geographies. According to the publication between January, 2011 and July, 2018, T. mentagrophytes is the predominant dermatophyte isolated today that followed by M. canis, T. violaceum and T. rubrum. Early diagnosis and timely treatment of tinea capitis is critically important to prevent from scar formation.
Conflicts of interest: The authors reported no conflicts of interest.
