Usefulness of Histological Examination for the Diagnosis of Onychomycosis

Abstract

Background: Direct microscopy and culture tests currently used in the diagnosis of nail mycosis can yield false-negative results, and confirmation of the pathogenic agent, especially in non-dermatophyte infections, is often a lengthy process. Objective: The aim of this study was to investigate the usefulness of the histological examination of nail clipping samples in supplementing the standard microscopic and culture techniques for the diagnosis of onychomycosis. Patients and Methods: One hundred and seventy-two subjects affected by nail alterations suggestive of onychomycosis were evaluated. Nail specimens were studied with 3 different techniques: direct microscopic examination of a 40% KOH clarified preparation, fungal culture and histological examination. Patients positive for fungal infection were re-evaluated with the same techniques after treatment with oral terbinafine, fluconazole or itraconazole and topical application of bifonazole or ciclopirox for 2 months. Results: Direct microscopy was positive in 102 (59.3%) nail specimens. The culture test was positive in 90 cases (52.9%), showing a dermatophyte in 45, a yeast in 23 and a mould in 22 samples. The histological examination was positive in 94 (54.6%) samples. In 4 cases, it was the only investigation confirming the clinical diagnosis of nail mycosis. In most of the cases, the morphological aspect of the hyphae and/or spores suggested also to which group of pathogens (dermatophytes, yeasts or moulds) the mycetes observed in the histological sections could be ascribed. The concurrent presence of a dermatophyte and a mould was evidenced in a few specimens. The control histological examination at the end of the treatment showed negative results or residual non-vital hyphae and/or spores. Conclusions: Results of the present study indicate that the histological examination of nail clipping specimens is a relatively inexpensive, rapid and easily performed procedure. It is useful to confirm or refute the results of routine microscopy and culture tests. Moreover, nail histopathological observation may help in ascribing a pathogenic role of non-dermatophyte isolates and evaluating the effectiveness of antifungal treatment.

Clinico-Mycological Study of Fungal Biofilms in Recalcitrant Onychomycosis

“…However, nail specimen cultures in the present study showed highly positive results for the presences of fungal organisms which are in accordance with Raghavendra et al The isolated fungal results in our study are compatible with many other studies reported that dermatophytes, mainly Trichophyton rubrum "T. rubrum", as the most common fungal organisms involved in onychomycosis followed by yeasts, mainly candida albicans ''C. albicans'', in many countries as Great Britain, Egypt and India [5,13,[20][21][22][23][24]. Biofilm has become the focus of the era and is considered to be one of the important causes of chronic recalcitrant infections globally.…”

Establishment of a Novel Model of Onychomycosis in Rabbits for Evaluation of Antifungal Agents

“…Although there are reports that describe histological findings in human onychomycosis and that confirm the value of histopathological examination in making the diagnosis (4,11,17,19), the route of infection and how the fungi behave in the nail plate have not been determined in detail.…”

Comparison of Diagnostic Methods for Onychomycosis: a Controlled, Prospective Study

“…Tekrarlayan KOH incelemeler ve kültür negatif sonuç verdiğinde fungal enfeksiyonun varlığını değerlendirmede tırnak ünitesinin histopatolojik incelemesi tavsiye edilmektedir (4,8,17,18). Yapılan bazı çalışmalarda ise tırnağın standart biyopsisinin incelenmesinin önemi halen vurgulanmakla birlikte, teknik olarak ağrılı olması ve kalıcı hasar bırakabilmesi ve uzun zamanda sonuç alınması nedeniyle pratikte uygun değildir (9,18). Son yıllarda tırnak plağının tırnak makasıyla kesilerek histolojik incelemesi, diğer insizyonel biyopsi yöntemlerine iyi bir alternatif olarak öneril-mektedir (18).…”