Background

Kerion is a type of tinea capitis(TC) often caused by zoophilic dermatophytes. Aspergillus protuberus is a species of fungus belonging to the genus Aspergillus; it was previously considered a member of the section Versicolores that can cause opportunistic infections in immunocompromised patients. However, A. protuberus has recently been described as a separate species [1]. Although the members of Aspergillus section Versicolores have been implicated in rare cases of lung, eye, and nail infections [2,3,4], there is no published report of human scalp mycosis caused by A. protuberus. Here, we report a case of kerion-type scalp mycosis that was identified as being caused by A.protuberus infection through mycological examination.

Case presentation

A 5-year-old girl presented with a pyogenic mass and pain of the scalp for 8 days, plus fever for 2 days. Surgical incision and drainage of the mass was performed, and cefuroxime and metronidazole was administered intravenously in the local hospital, but there was no obvious improvement. The skin lesions gradually increased, part of which formed an ulcer surface, and the purulent secretion increased. A fever began 2 days prior to admission, with a highest temperature of 39 °C. So, she came to our clinic for further diagnosis and treatmenton February 12, 2018. The patient was living in the countryside and had a history of dog contact; however, she was too young to recall a history of trauma. She was normally healthy with no similar diseases, other infectious diseases, or genetic diseases in her family.

Cutaneous examination revealed several ulcers of different sizes fused into a large 10 by 12 cm tender erythematous boggy swelling over the scalp with significant loss of hair, and yellowish-brown to hemorrhagic crusts. Removal of the crusts revealed seropurulent discharge. There was obvious stench and tenderness in the lesions (Fig. 1a).

Fig. 1
figure 1

a A large 10 × 12 cm sized erythematous boggy swelling over the scalp with several ulcers and hair loss. b After 70 days of treatment,the lesions were resolved, leaving residual scarring alopecia

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A routine blood test showed the white blood cell count to be 12.41 × 109/L (4–109/L), consisting of 8.90 × 109/L (2–7 × 109/L) neutrophils at a percentage of 71.70% (25–60%). The erythrocyte sedimentation rate (ESR) was 43 mm/h (0–20 mm/h). Routine urine, fecal, liver function, and renal function examinations revealed no obvious abnormalities. Bacterial culture yielded growth of Staphylococcus aureus.

Affected hair and excretion from the ulcer were collected and prepared for fluorescent brightening agents and Evans blue staining using a 10% potassium hydroxide (KOH) solution. We found fungi with septate hyphae inside the hair root (Fig. 2a). These samples were then inoculated onto Sabouraud agar (OXOID, Inc., Basingstoke, Hampshire, U.K.) and Czapek’s agar (OXOID, Inc., Basingstoke, Hampshire, U.K) and incubated at 30 °C. Growth was apparent within 15 days on all agar plates. The colonies were initially gray and fluffy and spread rapidly; eventually, the colonies became hairy and reached a diameter of 8 cm (Fig. 2b).

Fig. 2
figure 2

a Fungal fluoroscopy showed septate hyphae inside the hair root. b Black and hairy colonies in 15 d

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DNA was extracted following the Quick CTAB and PCR protocols as described previously [5]. The sequences of ribosomal internal transcribedspacer (ITS) and β-tubulin (BT2)were amplified (Table 1). DNA from each isolate was amplified by PCR in 12.5 ml reaction volumes using the primers and protocols described previously [6]. Blast results of the sequences in GenBank revealed that ourisolate belonged to Aspergillusprotuberuswith 99–100% similarity to depositeditems.The phylogenetic tree was made using MEGA v. 7.0.3.Phylogenetic analysis of concatenated loci ITS and BT2 showed that the reported clinical isolate (Temporarynamed Xian01) was definitivelynested within the A.protuberus species cluster (Fig. 3).

Table 1 Primers and PCR amplification conditions used for molecular identification
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Fig. 3
figure 3

Phylogenetic analysis of A.protuberus(isolate of the present case temporary named Xian01). Phylogenetic tree resulting from maximunlikehood (ML) and neighbor-joining (NJ) analysis for the ITS and BT2 genes

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The patient was diagnosed with scalp mycosis caused byA.protuberus, and secondary S.aureus infection. She began a treatment course oforal terbinafine (125 mg/day, 14 days) and methylprednisolone(8 mg/day, 5 days), intravenous mezlocillin sodium, sulbactam sodium (1.875 g/day, 7 days), compound glycyrrhizin (20 ml/day, 14 days), a wet dressing of ethacridine lactate and topical naphthotifen ketoconazole ointment, and fusidic acid cream. After the above described treatment, all the original lesions formed scabs without purulent secretions. Fluorescence microscopy for fungal detection showed negative result. The patient continued treatment with oral terbinafine (125 mg/day, 42 days that was decreased to 125 mg/two days, 14 days) and compound glycyrrhizin(25 mg/day, 56 days), with topical naphthotifen ketoconazole ointment. This treatment regimen cured the patient without adversely affecting liver function or resulting in other adverse drug-related events. Most of the patient’s hair regrew with only small areas of alopecia left (Fig. 1b). No relapse was observed during the 6 months of follow-up.

Discussion and conclusions

Scalp mycosis is often caused by dermatophytes is also referred to as TC. It is mainly observed in school-going children, and rarely in adults. Close contact with patients with TC, animals, and contaminated objects are the main routes of infection [7]. It can also occur in adults with diabetes, infection, organ transplantation, and other immunosuppressive conditions, and in individuals taking immunosuppressive drugs [8]. Kerion represents an inflammatory variant of TC caused by a dramatic immune response to fungus [9, 10]. The lesion begins as a group of inflammatory follicular papules, gradually fusing into a protuberant inflammatory mass with a soft texture. The surface then transforms into honeycomb-shaped pus-discharging pores. Secondary bacterial infection leads to abscess formation [11, 12]. This type of infection can destroy hair follicles, thus potentially leading to permanent alopecia and scar formation. Therefore, early diagnosis and timely treatment are very important. However, due to the obvious inflammation of the hair follicle and the surrounding area, it is often misdiagnosed and treated as scalp pyoderma, carbuncle,or cellulitis. Incision and drainage aggravate the infection and lead to a delay in treatment of the disease. Therefore, any boggy lesion with hair loss over the scalp and non-responsive to antibiotics should be suspected as fungal infection and be subjected to mycological examination, especially in children [13].

The etiological agents responsible for causing kerion are most commonly zoophilic dermatophytes such as Microsporum canis and Trichophyton violaceum [9, 10]. To our knowledge, there are no published reports of kerion-type scalp mycosis caused by A.protuberus. In this case, the patient had a history of contact with dogs and lived in rural areas with poor hygienic conditions. Although the medical history is short, the disease was aggravated by misdiagnosis and inappropriate incision and drainage at local hospitals, with severe infections and inflammatory reactions that were complicated by S. aureus infection. Fortunately, fungal infection was promptly detected and diagnosed. However, it is unclear why A. protuberus, not the common zoophilic dermatophyte, caused this infection. Borsa as reported a case of vaginitis caused by A. protuberus. To the best of our knowledge, there is no other published case of human infection caused by this species [14]. Other members of Aspergillus section Versicolores have been found in rare cases of lung [2], eye [3, 4], ear [15], bone [16], and nail [17] infections, mainly in patients with other underlying conditions and immunocompromised statuses. The patient in this case report was in good physical condition without any systemic diseases or immunosuppressive status. Apart from the contact with dogs, frequent exposure to soil and crops and careless injuries while playing were not excluded as routes of transmission. However, the demographic characteristics, probable origin, and route of transmission still need further investigation.

As for the treatment, itraconazole, fluconazole, and amphotericin B performed poorly in deep infections of A. protuberus [2, 4]. However, in superficial infection, terbinafine, itraconazole, and voriconazole were all effective [3, 15, 17]. Although griseofulvin is the traditional “gold standard” for general TC, its side effects limit its use at present [8, 18]. New antifungal agents, itraconazole and terbinafine, are widely used nowadays; however, itraconazole is rarely used in children due to limited clinical data. Only when the advantages outweigh the disadvantages, it can be cautiously used in children. Terbinafine, a lipophilic and keratophilic agent, has high concentrations in skin, hair, and nails, and has broad-spectrum antifungal activity (against dermatophytes, yeast, Aspergillus species, Histoplasma capsulatum etc.). It can be used in children over 2 years old, so it is often used as a first-line medication for TC in children [18]. Pediatric dosages are weight-based, at 62.5 mg (10–20 kg) or 125 mg (20–40 kg) daily. Hepatotoxicity is the main adverse reaction of the systemic use of antifungal drugs. Therefore, liver function should be monitored during their use. When transaminase is slightly elevated, liver protectants should be given timely. When liver function damage is serious, it is necessary to stop treatment. The standard of clinical cure is subsidence of skin lesions, but fungal reexaminations every 2–4 weeks are recommended, because mycological cure is the gold standard [19]. Although there is no standard treatment for kerion-type scalp mycosis caused by A. protuberus in the literature, we still referred to the general therapeutic schedule for TC. Because of its strong reaction to allergy similar to kerion, we adopted a short course of oral corticosteroids to reduce inflammation and the possibility of permanent scarring or alopecia. In addition, because the patient had a secondary bacterial infection, we also gave her antibiotics at the initial treatment. The therapeutic effect was good and resulted in mycological cure. Most of her hair regrew with no relapse during the six months’ follow-up.

To our knowledge, we report the first case of kerion-type scalp mycosis caused by A. protuberus; this report was supported by clinical, microbiological, and molecular data. It reminds clinicians that besides general dermatophytes, novel fungal infectious agents can also cause kerion-type scalp mycosis. Mycological examination is a useful tool to recognize pathogens. Any boggy lesions with hair loss over the scalp and non-responsive to antibiotics should be suspected as resulting from fungal infection, and mycological examination should be performed, especially in children.