Onychomycosis is a common problem. Today, the gold standard in the diagnosis of onychomycosis is the direct microscopy and fungal culture. But direct microscopy is regarded as having a low sensitivity and fungal culture takes long time. In addition, in cases of controlling the antifungal treatment course, the present gold standard is often not a reliable tool because of the inhibition of the fungal growth in the culture.
The purpose of this study was to compare the present gold standard with histological examination with periodic acid-Schiff staining (PAS) of nail clippings in the diagnosis of onychomycosis in a large cohort.
We prospectively evaluated 1146 nail samples from 851 patients with clinical signs of onychomycosis using direct microscopy and fungal culture in comparison with PAS-stain.
A total of 631 nail samples revealed a positive result in at least one test. The most sensitive single test for the diagnosis of onychomycosis was PAS with 82%, followed by culture (53%) and direct microscopy (48%). In 64 cases, in which a prediagnostic antimycotic treatment has been initiated, PAS showed to have by far the highest sensitivity (88%) in comparison with culture (33%) or direct microscopy (50%).
Periodic acid-Schiff staining is the single method with the highest sensitivity in terms of detection of fungal elements (hyphae) in nail specimens. Especially in cases with prior antifungal treatment, histological analysis of PAS-stained nail clippings should be considered as an appropriate diagnostic tool.
[Show abstract][Hide abstract] ABSTRACT: Surgical pathology testing for onychomycosis using periodic acid-Schiff staining is the "gold standard." However, routine histopathological methods of processing nail clippings can be limited by poor section quality, higher costs, and delayed turnaround times for some specimens because of tissue hardness.
We investigated the utility of sodium hydroxide (NaOH) pretreatment of nail specimens submitted for the histopathologic evaluation of onychomycosis.
We report our validation of a sodium hydroxide (NaOH) pretreatment protocol during a 7-month study period from 2009-2010. Nail clippings (n = 45) were divided into NaOH-treated and routine processing halves and submitted in separate tissue blocks for parallel processing, embedding, sectioning, and staining for hematoxylin-eosin and periodic acid-Schiff. Histologic sections were scored for section quality and statistical analysis performed.
NaOH pretreatment yielded higher quality sections for both hematoxylin-eosin-stained (P < .001) and periodic acid Schiff-stained (P < .001) slides with reduced tissue folding and fragmentation, improved ease of cutting, and adherence of the tissue to glass slides.
Direct comparison of the proposed NaOH pretreatment protocol with other pretreatment techniques was not performed.
NaOH pretreatment of nails submitted for a clinical suspicion of onychomycosis is a simple, rapid, and easily adopted method that leads to improved tissue section quality for optimal histopathologic evaluation and diagnosis. Improved tissue sections and adherence to glass slides can reduce the need for repeat sections, thereby reducing costs and preventing delays in turnaround time.
Journal of the American Academy of Dermatology 08/2011; 66(4):655-60. DOI:10.1016/j.jaad.2011.05.046 · 4.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recent observations indicate that Arthroderma benhamiae can cause bullous tinea, that onychomycosis increasingly occurs in children and that molds can cause tinea-like lesions. If a mycotic infection is suspected, the pathogen needs to be identified. The first genetic assays for the detection of dermatophytes have successfully been tested under routine conditions. Using appropriate techniques, genetic diagnosis is faster and more sensitive than a culture. Laboratory standards that would facilitate widespread implementation of genetic identification of dermatophytes have not yet been established. For the identification of yeasts, MALDI-TOF has already been established in many laboratories. This method is being refined for the diagnosis of hyphomycetes too. Newer antimycotics that are approved for certain systemic mycoses such as the triazoles voriconazole and posaconazole and the echinocandines caspofungin, micafungin und anidulafungin may be considered for dermatomycoses that cannot be treated by other therapies. Thermotherapy and photodynamic therapy are additional options in particularly difficult cases.
Der Hautarzt 04/2012; 63(5):390-5. DOI:10.1007/s00105-011-2259-x · 0.56 Impact Factor
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