Abstract

BACKGROUND: Onychomycosis is one of the most common nail disorders, but dermatologists have experienced poor efficacy ol therapy because of incorrect diagnosis. It has been reported that histopathologic evaluation of the nail plate by nail clipping might be a useful supportive method for identification of causative fungi showing higher detection rates. 

OBJECTIVE: This study was aimed to determine whether histopathologic examination support for identification of causative fungi and whether it increased. The diagnostic sensitivity of onychomycosis even in cases that those fungus culture fail to identify the causative fungi, and to clarify the relative frequency of causative fungi in onychomycosis. 

METHODS: Histopathologic findings of 218 onychomycotic nail samples, proven by KOH smear, were analyzed and compared with the results of fungus culture.

RESULTS: The results were as follows;

1. Histopathologic examination showed higher positive rate (73.9%) than that of fungus culture (35.8%) in identifying the etiologic fungi.

2. The 3 groups of causative fungi confirmed by fungus culture showed morphologically distinguishable characteristics in histopathologic examination: Dermatophytes showed septated long, thin and regular hyphae with or without arthrospores, while Candida sp. showed blastospores, grape-like clusters of regular spores and pseudohyphae. Mold exhibited irregular hyphae with variable width and aggregates of irregular spores. Mixed infections showed the characteristic findings of the corresponding groups at the different sites of the nail samples.

3. Frequency of the causative fungi by fungus culture was 88.5% of dermatophytes, 5.1% of Candida sp. and 6.4% of mold. In histopathologic examination, the frequency was considered as 80.7% of dermatophytes, 8.1% of Candida sp., 6.2% of mold and 1.9% of mixed infection.

4. In 42 of 59 samples of T. rubrum and 3 of 10 samples of T. mentagrophytes, hyphae were observed on the ventral and dorsal layer of the nail plate, respectively. In histopathologic sections, 88 of 130 samples of dermatophytes showed fungal element on the ventral layer of the nail plate and all 13 samples of Candida sp. on the subungal keratin layer and ventral layer of the nail plate.

CONCLUSION: Histopathologic examination in onychomycosis is considered to be simple, useful supportive method in studying the classification and distribution of causative fungi of onychomycosis and might be included in the routine laboratory tests for making the presumptive diagnosis of causative fungi of onychomycosis. Moreover, we can determine the site of involvement of the fungi in the nail, so we can get useful informations about mixed infections or contaminations. 

Keywords

Fungus culture Histopathologic examination Onychomycosis

KJMM 1997 June;2(1):31-42(12). Epub 2016 February 25
Copyright © 1997 by Korean Journal of Medical Mycology

Language

Korean/English

Author

Sung Wook Kim; Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul, Korea
Baik Kee Cho; Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul, Korea

Corresponding

Sung Wook Kim, Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul, Korea.

Publication history

Acknowledgements

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Sung Wook Kim

Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul, Korea

Baik Kee Cho

Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul, Korea

Since epub date 2016 February 25