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CORRESPONDENCE
Year : 2023 | Volume
: 41
| Issue : 1 | Page : 62-63
Combination simple wet gauze technique placating children and calcofluor white staining microscopy enhances the diagnostic capability in kerion
Sushmita Pradhan1, Jinghong Huang2, Xin Ran3, Chaoliang Zhang4, Daisuke Tsuruta5, Hisayoshi Imanishi5, Yuping Ran3
1 Department of Dermatovenereology, West China Hospital, Sichuan University, Chengdu, China; Department of Dermatology and Venereology, Province Hospital, Birendranagar, Karnali, Nepal; Department of Dermatology, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
2 Department of Dermatology, Dujiang Yan Medical Center, Dujiang Yan, China
3 Department of Dermatovenereology, West China Hospital, Sichuan University, Chengdu, China
4 State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
5 Department of Dermatology, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
Correspondence Address:
Prof. Yuping Ran
Department of Dermatovenereology, West China Hospital, Sichuan University, No. 37, Guo Xue Xiang, Wuhou Dist., Chengdu, Sichuan Prov., 610041
China
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/ds.DS-D-22-00201
Dear Editor,
Tinea capitis is a childhood disease caused by dermatophytes, Trichophyton or Microsporum species and was estimated to carry 1% of all superficial fungal infections. Zoophilic dermatophytes mainly induce kerion. It is most common in 5–10 years' age children and rare in infancy.[1] Scraping of lesions, dermoscopy, 20% potassium hydroxide (KOH) wet mount or calcofluor white staining microscopy, and fungal culture with Sabouraud's dextrose agar (SDA) are diagnostic tools for kerion. Herein we report a case in which a combination approach of wet gauze technique and calcofluor white staining assisted in rapid diagnosis that failed with routine KOH microscopy.
A 4-year-old girl presented with fever, pain, erythematous, boggy swelling plaque, and purulent discharge in the central scalp for 2 months. Physical examination revealed erythematous plaque with exudates on the scalp [Figure 1]a. She had a history of contact with domestic rabbits. To reduce her anxiety during the sample extraction, a gauze piece soaked in sodium chloride solution was placed on the infected site for around 5 min, which helped soften the cuticle surface of hair debris by moisture absorption. Infected short, broken hair debris that adhered to wet gauze was lifted using aseptic forceps for further examinations. The child was more comfortable and cooperative.
Figure 1: (a) An erythematous boggy swelling plaque, hair loss, and exudates on the scalp before treatment of a 4-year-old child. (b) Polarized dermoscopy shows erythematous plaques, yellow scales, an ambiguous “comma” hair (black arrows), dystrophic scalp tissues, and peripilar casts without specific changes on the hair shaft (×50) (c) Complete remission of the lesions and hair regrowth after 12 weeks of treatment. (d) Polarized dermoscopy shows clearance of large plaques with erythematous base and vessels, with hair regrowth after 12 weeks of treatment (×50) (Dino-Lite AM7013MZT by AnMo Electronics Corporation, a Chinese distributor, JEDA)Polarized dermoscopy showed erythematous plaques, yellowish scales, an ambiguous “comma” hair, dystrophic scalp tissue, and peripilar casts without specific changes on the hair shaft [Figure 1]b. In the beginning, 20% of KOH failed to demonstrate any positive findings. Direct microscopy using calcofluor white staining of the hair debris highlighted ectothrix spores and hyphae around the hair root [Supplementary Figure 1]a (Please refer to the cover image of this issue). Fungal culture (SDA) from hair debris and crusts demonstrated fluffy white colonies [Supplementary Figure 1]b. Calcofluor white staining on slide cultures with SDA [Supplementary Figure 1]c and with potato dextrose agar [Supplementary Figure 1]d, respectively, revealed flat suede-like colonies. Under scanning electron microscopy, dense clusters of grape-shaped microspores were found [Supplementary Figure 1]e. The sequence of the internal transcribed spacer (ITS) region in the ribosomal RNA gene of strain amplified with ITS1 and ITS4 primer set was 100% homologous (691/691 bp) with Trichophyton mentagrophytes (GenBank MN173149.1). Diagnosis of kerion was confirmed. The child responded well to oral itraconazole 100 mg/day (5 mg/kg/day) once daily with milk for better absorption without any side effects, daily hair washes with 2% ketoconazole shampoo, and application of 1% naftifine and 0.25% ketoconazole cream. Routine liver function examination was within the normal limits during the therapy. After biweekly follow-ups, repeated calcofluor white staining of hair debris was negative. Moreover, after 12 weeks of complete treatment, the lesion was cleared [Figure 1]c and [Figure 1]d.
Pre-wet gauze pad application for surface sampling is a reliable technique requiring aseptic sample collection techniques to avoid microbiological contamination for rapid exfoliation of the dried surface samples. Hay and Borchers described moistened gauze technique in carefully removing crusts for diagnostic purposes, allowing quick healing by considering the possibility of coexisting bacterial infection.[2],[3] Borchers used firmly rubbed tap water-moistened gauze. However, we preferred sodium chloride solution moistened gauze placed for a specific time to avoid contamination of hair debris by tap water and discomfort caused by firm rubbing.
Kerion progresses quickly easily destroying scalp skin tissue but has inadequate time to destroy the hair shaft. Routine KOH microscopy is challenging to detect the positive findings of fungal hyphae in the damaged hair. Calcofluor white staining microscopy can easily mark fungal cell walls,[4] can “specifically” demonstrate the hyphae around the hair shaft in the early stage of infection, despite being relatively “normal” under dermoscopy. This case emphasizes the sensitivity and importance of calcofluor white staining microscopy for rapid diagnosis.
Dermoscopy is a rapid, non-invasive, and painless technique.[5] “Comma” and “corkscrew” hairs are essential findings of tinea capitis under dermoscopy. Comma-shaped hairs are characterized by a sharply slanted end demonstrating an intermediate stage before the formation of dystrophic hairs, whereas corkscrew hairs are exaggerated coiled hair shafts.[6] Ambiguous comma hairs were noted in our case, except for normal findings of the hair shaft.
Kerion could easily be misdiagnosed when positive findings of hyphae are undetectable in routine KOH microscopy. The confirmation of diagnosis initially depends on accurate nondestructive sampling methods, providing a concrete path for further investigations, especially in more vulnerable children. The wet gauze technique enhances the diagnostic capability before routine mycological examinations. A combination of moistened gauze, dermoscopy, and calcofluor white staining microscopy can be a powerful recommendation to enhance the diagnostic capability, helping the physician improve patient management.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given the consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal patient identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
This work was partly supported by 1.3.5 project for disciplines of excellence (ZYJC18033), West China Hospital, Sichuan University, and HX-Academician project (HXYS19003), West China Hospital, Sichuan University. The funding bodies had no role in the design of the study and collection, analysis, and interpretation of data or in writing the manuscript.Sasakawa Medical Scholarship Association.Conflicts of interest
Prof. Yuping Ran, an editorial board member at Dermatologica Sinica, had no role in the peer review process of or decision to publish this article. The other authors declared no conflicts of interest in writing this paper.
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