Comparative analysis in diagnosis by real-time polymerase chain reaction versus direct microscopy, culture, and histology in fungal infections of the nails, scalp, and skin

BACKGROUND

The diagnosis of superficial fungal infections is the subject of intensive research in many countries around the world. The diagnostic methods used are diverse, including both conventional and innovative techniques.

METHODS

This study evaluates the sensitivity, specificity, and efficacy of the real-time polymerase chain reaction (PCR) methodology and compares them with those of the conventional methods - direct microscopic, cultural, and histological examinations of materials from hair, skin, and nails - in order to demonstrate the benefits and significance of real-time PCR for the diagnosis of dermatophytic infections.

RESULTS

The values obtained for the sensitivity, specificity, and efficacy of direct microscopic, cultural, histological, and real-time PCR studies are as follows: 63.71, 88.89, and 72.96% (P < 0.001); 58.06, 100, and 73.47% (P < 0.001); 85.96, 100, and 90.70% (P < 0.001); 88.52, 100, and 92.63% (P < 0.001).

CONCLUSION

The use of real-time PCR in the diagnosis of dermatophytic infections is a relatively new approach in mycology and is subject to testing and experience from its use. The results are promising, but the method has not yet established itself as a new gold standard in the diagnosis of superficial fungal infections caused by dermatophytes, though its application would be very useful in identifying isolates without conidiogenesis or absence of growth.

Prevalence of onychomycosis in patients with diabetes mellitus: A cross-sectional study from a tertiary care hospital in North India

Background Though diabetes mellitus (DM) is a well-recognised risk factor for onychomycosis (OM), the epidemiology of OM in diabetic patients remains largely unexplored, especially from the Indian subcontinent. Aims and objectives To estimate the prevalence of OM in diabetic patients, to identify and analyse risk factors, and correlate the severity of nail changes with glycemic control (HBA1c). Methods This cross-sectional, analytical study involved 300 diabetic patients. Patients with the clinical diagnosis of OM, supplanted by at least two of the four tests (KOH, culture, onychoscopy and nail histopathology) were considered cases of OM. Demographic and haematological profile was analysed using chi-square test/ Fischer's exact test. Logistic regression was applied to assess the independent risk factors. Results The prevalence of OM in DM patients was 34% (102/300) and significant risk factors included; age >60 years, male gender, closed shoes, disease duration >5 years, high BMI (>25) and lack of awareness about nail changes. Distal and lateral subungual OM (78%) was the commonest presentation followed by proximal subungual OM, superficial OM and total dystrophic OM. Correlation between HbA1c and the number of nails involved was found to be significant. Limitation As cases were recruited from a hospital setting, there could be chances of Berksonian bias. Conclusion The prevalence of OM in diabetic patients is high and the severity of nail changes correlates with HbA1C levels. It is important to diagnose OM early in order to treat and prevent complications.

Clinical evaluation of a dermatophyte RT-PCR assay and its impact on the turn-around-time: A prospective study

Onychomycosis is an important public health problem whose prevalence continues to grow and impact public health at several levels. Nevertheless, today the main diagnostic methods used in routine practice have many drawbacks. The aim of this study was to evaluate, for the first time, the clinical performance of a new multiplex polymerase chain reaction (PCR) (Novaplex®) in the identification of the causative agent on nail samples, and its impact on the turnaround time, compared to our traditional laboratory methods. From June 2022 to December 2022, all nail samples sent to our laboratory for suspected onychomycosis were included in this prospective study. We collected for each sample the results obtained with the Novaplex® PCR method and with the traditional direct microscopy examination and culture. Each discordant result was checked using a third method, which is another PCR method (DermaGenius® kit) as a resolver. For culture-positive samples, a turnaround time was calculated and compared to the one obtained with the Novaplex® method. A total of 131 samples were included. Among them, 5 were positive (3.8%) on direct microscopy, 33 were positive (25.2%) after culture, and 98 were negative (74.8%). All positive (n = 33) and negative (n = 69) cultures were also positive/negative with the Novaplex® PCR. Twenty-nine samples were positive with the Novaplex® method but negative with culture (discordant results). The percentage agreement between the culture and the Novaplex® methods was 77.9% (102 out of 131). While tested with the resolver (DermaGenius® PCR), 28 out of 29 discordant results were similarly found positive. The percentage agreement between the two PCR methods (Novaplex® and DermaGenius®) was 96.6%. The Novaplex® PCR method evaluated proved to be very reliable and allowed the direct identification of 62 out of 131 positive samples (47.3%) with the following distribution: 79.0% of Trichophyton rubrum complex, 11.3% of Trichophyton mentagrophytes complex, 6.5% of both Trichophyton rubrum complex and Trichophyton mentagrophytes complex, and 3.2% of Candida albicans. The median time [± 95% CI] for positive culture (between incubation and validation of the final identification) was 15 [12-23] days, while the turnaround time for the Novaplex® method adapted to our clinical laboratory routine is ≤7 days. Laboratory confirmation of onychomycosis is crucial and should always be obtained before starting treatment. The evaluated PCR method offered a rapid, reliable, robust, and inexpensive method of identification of the causative agent compared to traditional methods.

Comparison of diagnostic methods in onychomycosis

Aim: Onychomycosis is a chronic fungal infection of the nail bed, plate, or matrix. This study aimed to compare the sensitivity of three diagnostic methods in the diagnosis of onychomycosis. Material and Method: This study included 39 patients with a clinical diagnosis of onychomycosis of the toenails, who presented to Medipol Mega University Hospital between May 2019 and August 2022. Using the nail samples taken from the patients, the results of the direct microscopic examination with standard potassium hydroxide (KOH), histopathological examination performed with periodic acid-Schiff (PAS) staining, and fungal agents that grew in fungal culture were noted. Results: Eleven (28.2%) patients were female, and 28 (71.8%) were male, with the mean age being 43.1±13.9 years. Of the patients, 53.8% had distal subungual onychomycosis and 46.2% had total subungual onychomycosis. The mean disease duration was 38.8±24.5 (12-120) months. Fungal infection was detected on direct microscopic examination with standard KOH in 66.7% of the patients, culture growth in 38.5%, and PAS staining on histopathological examination in 71.8%, and the sensitivities of these methods were determined as 74.3%, 49.2%, and 80%, respectively, with the negative predictive values being 30.8%, 16.7%, and 36.4%, respectively. Conclusion: Among the investigated methods, histopathological examination with PAS staining was found to have the highest sensitivity and negative predictive value in the diagnosis of onychomycosis.

Deep Learning Assisted Diagnosis of Onychomycosis on Whole-Slide Images

Background: Onychomycosis numbers among the most common fungal infections in humans affecting finger- or toenails. Histology remains a frequently applied screening technique to diagnose onychomycosis. Screening slides for fungal elements can be time-consuming for pathologists, and sensitivity in cases with low amounts of fungi remains a concern. Convolutional neural networks (CNNs) have revolutionized image classification in recent years. The goal of our project was to evaluate if a U-NET-based segmentation approach as a subcategory of CNNs can be applied to detect fungal elements on digitized histologic sections of human nail specimens and to compare it with the performance of 11 board-certified dermatopathologists. Methods: In total, 664 corresponding H&E- and PAS-stained histologic whole-slide images (WSIs) of human nail plates from four different laboratories were digitized. Histologic structures were manually annotated. A U-NET image segmentation model was trained for binary segmentation on the dataset generated by annotated slides. Results: The U-NET algorithm detected 90.5% of WSIs with fungi, demonstrating a comparable sensitivity with that of the 11 board-certified dermatopathologists (sensitivity of 89.2%). Conclusions: Our results demonstrate that machine-learning-based algorithms applied to real-world clinical cases can produce comparable sensitivities to human pathologists. Our established U-NET may be used as a supportive diagnostic tool to preselect possible slides with fungal elements. Slides where fungal elements are indicated by our U-NET should be reevaluated by the pathologist to confirm or refute the diagnosis of onychomycosis.

Epidemiological analysis of nail aspergillosis and non-dermatophyte moulds. Criteria for the involvement of Aspergillus in 102 cases of onychomycosis at Montpellier University Hospital, France (1991-2019)

BACKGROUND

Moulds are often wrongly considered contaminants, not very sensitive to conventional antifungal treatments, but they may cause ungual hyphomycosis, particularly Aspergillus. Due to the lack of precise diagnostic criteria, their real impact is underestimated.

OBJECTIVES

Retrospective descriptive analysis of all ungual hyphomycosis cases diagnosed at Montpellier Hospital from 1991 to 2019 to: (i) determine the incidence of onychomycosis by pseudo-dermatophytes and moulds; (ii) perform an epidemiological analysis of nail aspergillosis; and (iii) provide simple criteria for mould involvement in onychopathy.

PATIENTS/METHODS

Data concerning 4053 patients were collected: age, sex, onychomycosis location, direct examination results, species(s) identified and fungal co-infections. Moreover, clinical data of patients with nail aspergillosis were analysed to identify potential contributing factors, and the classical criteria for mould involvement in onychopathy were critically reviewed.

RESULTS

A pseudo-dermatophyte or a mould was involved in nail colonisation in 17.25% of patients (men/women ratio: 0.70; mean age: 53.1 years). The identified hyphomycetes belonged mainly to the genera Fusarium (45.68%), Scopulariopsis (30.23%) and Aspergillus (16.94%). Analysis of the clinical reports of 102 patients with ungual aspergillosis (men/women ratio: 0.67; mean age: 56.3 years) identified cardiovascular (43.9%), endocrine (25.8%), cancer (19.7%) and skin (18.2%) diseases as contributing factors.

CONCLUSIONS

The adoption of simple and reliable criteria (ie, characteristic filaments on direct microscopic examination after periodic acid-Schiff staining, growth at seeding points in culture) allows determining the formal involvement of a mould in chronic onychopathies and avoiding possible side effects and costs of empirical or inappropriate and repetitive treatments.

Histopathological Findings in Nail Clippings With Periodic Acid-Schiff-Positive Fungi

BACKGROUND

Periodic acid-Schiff (PAS) staining of nail clippings is an adjunct diagnostic tool for onychomycosis.

OBJECTIVE

To detect histopathological findings as clues to the presence of PAS-positive (+) fungal elements in nail clippings.

METHODS

Four hundred sixteen consecutive nail clippings suspected of onychomycosis were stained with hematoxylin and eosin, and with PAS stains. All cases were studied histopathologically. The clinical files of the cases with neutrophils were reviewed.

RESULTS

PAS+ staining for fungi were demonstrated in 159 (38%) of the nail clippings. Neutrophils, parakeratosis, plasma globules, and bacteria were observed in 43 (27%), 108 (67%), 80 (50%), and 80 (50%) of the PAS+ cases, respectively, and in 17 (6%), 109 (41%), 84 (32%) and 140 (54%) of the PAS- cases, respectively (P < 0.01). Neutrophils showed by far the highest specificity (93%), although with low sensitivity (27%) for the presence of PAS+ fungi. Among the 43 PAS+ and 17 PAS- specimens with neutrophils, only 1 (2.3%) and 3 (17%) had overt psoriasis, respectively.

CONCLUSION

Neutrophils in nail clippings may serve as a clue for onychomycosis. PAS staining with neutrophils is not necessarily associated with psoriasis.

Onychomycosis and Tinea Pedis in the Feet of Patients With Diabetes

This study aimed to determine the prevalence of onychomycosis and interdigital tinea pedis in a cohort of Spanish patients with diabetes in whom onychomycosis was clinically suspected (n = 101). Samples from a first toenail scraping and the fourth toe clefts were subjected to potassium hydroxide direct vision and incubated in Sabouraud and dermatophyte test medium. Fifty-eight samples were also analyzed by a pathologist using periodic acid-Schiff staining and Calcofluor white direct fluorescence microscopy. Onychomycosis was only confirmed in 41 patients (40.6%). The most frequent aetiological agent was Trichophyton rubrum, isolated in 10 patients (36%), followed by Candida parapsilosis in 7 patients (25%). Tests on the fourth toe cleft samples were only positive in 11 patients (10.9%), and in all cases, onychomycosis was also diagnosed. Neuroischemic foot was the only significant variable associated with onychomycosis in the univariate analysis (P < .01). A positive result for mycosis in the fourth toe cleft was found in 11 cases (10.9%) and was associated with a history of myocardial infarction (P< .01; odds ratio [OR]: 84.2, confidence interval [CI]: 6.8-1036.4) and neuroischemic foot (P< .01; OR: 13.7, CI: 12.6-71.6) in the multivariate model. In conclusion, the prevalence of onychomycosis and tinea pedis in patients with diabetes in whom onychomycosis was clinically suspected was 40.6% and 10.9%, respectively. In addition, onychomycosis was not always associated with tinea pedis. These results show that clinical diagnosis has low accuracy in people with diabetes mellitus, and that diagnosis should not be based on clinical toenail characteristics alone.

PAS stain based histological classification and severity grading of toenail onychomycosis

Onychomycosis is a common world-wide health issue. Accurate detection is essential for treatment. Multiple studies have shown that PAS-stain based histological visualization of fungal elements is superior to either direct microscopy with 20% potassium hydroxide, or fungal culture. However, PAS stain based histological classification and severity grading of onychomycosis are lacking in the literature. Here we reported a fungal detection rate of 47.87% based on an analysis of 13,805 toenails processed for H&E and PAS stains over a three year period. Based on the analysis of fungal density, distribution and infiltrating depth level in 858 PAS-positive toenails, we created a novel PAS stain based histological classification system to classify onychomycosis as occult onychomycosis (OO), focal or diffuse subungual onychomycosis (FSO or DSO), focal or diffuse plate onychomycosis (FPO or DPO), focal or diffuse subungual and plate onychomycosis (FSPO or DSPO) and superficial onychomycosis (SO). The severities of OO, FSO and FPO were graded as mild, DSO and DPO as moderate, FSPO and DSPO as severe infections, which revealed that more than 75% PAS positive toenails were severe infections. Evaluation of 97 paired toenails biopsied pre- and post-treatment from 47 patients demonstrated that the severity of infection was significantly reduced from severe to mild and moderate levels. These data indicate that the current histological classification evaluates not only the severity of the fungal infection but also the response to treatment. We further propose a guideline for treatment of onychomycosis based on the histological classification and severity.

Direct examination, histopathology and fungal culture for the diagnosis of onychomycosis: A retrospective, comparative study on 2245 specimens

BACKGROUND

Onychomycosis affects 5.5% of the general population and represents up to 50% of all nail diseases. Diagnosis and pathogen identification are essential in order to plan an adequate treatment. Many diagnostic techniques are available, and however, no solid data regarding comparison between different techniques over a large number of specimens are available to date.

OBJECTIVES

To compare sensitivity and specificity of direct examination, histopathology and fungal culture in our referral mycology laboratory.

METHODS

Nail specimens received at the cutaneous pathology and mycology laboratory of the University Hospital Saint-Pierre (Brussels, Belgium) between 1 January and 15 May 2018 were retrospectively analysed. All specimens were submitted to direct examination and culture. In cases of adequate specimen size, histopathology was performed. Fungal culture was considered the gold standard for diagnosis.

RESULTS

A total of 2245 nail samples were included in the study. Onychomycosis was diagnosed in 1266 specimens. Sensitivity and positive predictive value were found to be higher for direct examination compared to histopathology, while sensitivity of direct examination was found to be lower. Combined approach with all the three techniques showed the highest rate of positivity, followed by the association of direct examination and histopathology.

CONCLUSIONS

To our knowledge, this study included the largest number of nail specimens to date, allowing a comparison between direct examination, culture and histopathology. Direct examination showed to be the most performing technique in routine practice. Histopathology represents the most effective option in cases where both specimen size and laboratory resources are adequate. Our paper adds to the literature the 'real-life' experience of the mycology laboratory of a referral centre for nail diseases.

PAS and GMS utility in dermatopathology: Review of the current medical literature

The American Society of Dermatopathology has established an Appropriate Use Criteria (AUC) Committee with the intention of establishing evidence-based recommendations regarding the appropriateness of various ancillary tests commonly utilized by dermatopathologists. Periodic acid Schiff (PAS) and Grocott (or Gomori) methenamine silver (GMS) stains represent some of the most commonly employed ancillary tests in dermatopathology. The utility of these tests was targeted for evaluation by the AUC. This literature review represents a comprehensive evaluation of available evidence for the utility of PAS and/or GMS staining of skin and nail biopsies. In concert with expert opinion, these data will be incorporated into future recommendations by the AUC for PAS and GMS staining in routine dermatopathology practice.

Pediatric nail disorders: a review

PURPOSE OF REVIEW

Nail disorders represent an uncommon subset of complaints seen in pediatric dermatology. There is a wide array of disorders that can affect the nail unit in children, including infectious, inflammatory, neoplastic, congenital, and traumatic processes. In order to enhance familiarity with pediatric nail conditions, we review the background and treatment of the more common entities seen in pediatric onychology, including onychomycosis, onychomadesis, nail psoriasis, trachyonychia, longitudinal melanonychia, onychophagia, and onychocryptosis.

RECENT FINDINGS

Nail involvement in pediatric patients with psoriasis may indicate increased risk for both overall disease severity and the development psoriatic arthritis. In the evaluation of longitudinal melanonychia, the clinical findings that raise concern for subungual melanoma in adults are often found in benign nail unit nevi in children. In the systemic treatment of pediatric onychomycosis, new data raises the possibility that laboratory monitoring may be approached differently. In the approach to onychophagia, emerging pharmacotherapies include N-acetylcysteine.

SUMMARY

Most nail disorders in pediatric patients have an overall favorable prognosis. However, nail abnormalities can lead to patient and parental anxiety, decreased quality of life, pain, and functional impairment. Clinicians should be aware of these more common diverse entities in order to identify them and apply state of the art management for these issues. Additionally, the reader will learn factors related to these nail disorders, which may require systemic work-up and/or specialist referral.

Optical coherence tomography of onychomycosis: proposed terminology and a suggestion of practical usage

Onychomycosis is the most common cause of nail changes accounting for about half of all nail diseases. It is important to diagnose the fungal pathogen to prescribe adequate treatment, but as genus- and species-specific diagnostic tests can be time consuming and expensive, it is crucial to obtain representative tissue during nail scrapings. Optical coherence tomography (OCT) is a non-invasive imaging tool enabling real-time imaging of skin and tissue. Pilot studies using OCT have described morphological characteristics of onychomycosis, though diagnostic criteria of onychomycosis and other nail diseases are lacking. The aim of this study is to investigate the applicability of OCT to detect and localize fungal elements in nails with clinical signs of onychomycosis. OCT scans and nail scrapings were performed on all participants and only confirmed cases of onychomycosis were included in the data analysis. All scans were analyzed, and a set of morphological criteria based on known literature and deviations from healthy nail morphology were suggested. The suggested morphological features were: hyperreflective lines divided into sharply and diffusely demarcated; hyperreflective dots divided into singular and clustered patterns; irregular surface, divided into mild, moderate and severe degree; dark bands and disturbed architecture. The suggested OCT morphology is a refinement of previous studies, and though OCT cannot replace genus- or species-specific identification, it could be a useful assistance tool to increase diagnostic sensitivity of nail scrapings and laboratory tests as well as for monitoring treatment response.

[Evaluation of the usefulness of nail biopsy in the diagnosis of onychomycosis]

BACKGROUND

Onychomycosis affects between 2% to 30% of the world population. Nail biopsy may help in making a diagnosis and can distinguish between invasion and colonisation.

AIMS

To evaluate the diagnostic usefulness of nail biopsy with Periodic acid-Schiff (PAS) staining for onychomycosis, compared to direct KOH examination, culture and its combination in a reference laboratory in Colombia.

METHODS

The study included 66 patients in whom a blind and independent reading of the three tests was performed. The usefulness was defined based on the validity (sensitivity, specificity, Youden's index, likelihood ratios), performance (predictive values) efficiency (proportion of correctly diagnosed patients), and reproducibility (kappa coefficient).

RESULTS

The mean age of the patients was 55±16 years, and included 76% women. The direct tests with KOH were positive in 66.7% (n=44), 62.1% (n=41) were positive with culture, and 56.1% (n=37) with the biopsy. The main causal agents were non-dermatophytes moulds in 36.4% (n=24). The most frequent species were Neoscytalidium dimidiatum (n=11), Trichophyton rubrum (n=11), and Candida parapsilosis (n=13). The sensitivity of nail biopsy, when compared to the standard (KOH and/or culture), was 71%, specificity 83%, Youden's index 0.54, positive likelihood ratio 4.25, negative likelihood ratio 0.35, positive predictive value 92%, negative predictive value 52%, efficiency 74% and kappa coefficient 0.45. When biopsy was evaluated only in patients with onycholysis of the nail plate greater than 50%, all the parameters of diagnostic usefulness increased.

CONCLUSIONS

The overall usefulness of the biopsy was moderate for patients with more severe symptomatology, which makes its use advisable in cases of extensive onycholysis, and when discriminating colonisation from invasion is required.

Clinical features and nail clippings in 52 children with psoriasis

BACKGROUND/OBJECTIVES

Nail clipping, the act of cutting the distal portion of a nail for microscopic analysis, can complement the diagnosis of skin diseases with nail involvement, such as psoriasis. This study aimed to describe histopathologic findings on 81 nails from 52 children and adolescents with skin psoriasis and to determine whether these changes correlated with the severity of skin and nail involvement.

METHODS

Children with psoriasis were enrolled in this cross-sectional study to obtain Psoriasis Area and Severity Index (PASI) and Nail Psoriasis Severity Index (NAPSI) scores. The most altered nails were processed using periodic acid-Schiff with diastase staining.

RESULTS

Fifty-two patients with a median age of 10.5 years were included. The median Nail Psoriasis Severity Index score of the 20 nails from these patients was 17 (range 3-80). The most common findings were pitting (94.2%), leukonychia (73.0%), and longitudinal ridges (63.5%). Eighty-one nail fragments were collected by clipping. Neutrophils were found in 6 samples (7.6%) and serous lakes in 15 (19%). Median nail plate thickness was 0.3 mm (range 0.1-0.63 mm). Patients whose nails had neutrophils had a higher median PASI score (6.1 vs 2.0, P = .03). Patients whose nails had serous lakes had higher median PASI (5.3 vs 1.9, P = .008) and NAPSI (median 45.0 vs 18.0, P = .006) scores.

CONCLUSION

There seems to be a correlation between some microscopic nail features in children with psoriasis and their PASI and NAPSI scores, so nail clippings from children with suspected psoriasis may help with diagnosis, especially in the presence of neutrophils, and in excluding onychomycosis.

Confirmatory Testing Prior to Initiating Onychomycosis Therapy Is Cost-Effective

Background:

Onychomycosis can be investigated by sampling. Information gleaned includes nail bed involvement, nail plate penetration, fungal viability, and species identification. Testing samples can confirm a diagnosis. While diagnostic testing is considered useful in directing therapy, a substantial number of clinicians do not confirm diagnosis prior to treatment.

Objectives:

The aim of this study is to quantify the benefit of confirmatory testing prior to treating toenail onychomycosis.

Methods:

The cost of mycological cure (negative potassium hydroxide and negative culture) and the cost-effectiveness of confirmatory testing were determined using the average cost of potassium hydroxide (KOH), culture, periodic acid–Schiff (PAS), efinaconazole, ciclopirox, terbinafine, and itraconazole. Costs were obtained through literature searches, public domain websites, and telephone surveys to local pharmacies and laboratories. To represent the potential risks of prescribing onychomycosis treatment, the costs associated with liver monitoring, potential life-threatening adverse events, and drug-drug interactions were obtained through public domain websites, published studies, and product inserts.

Results:

PAS was determined to be the most sensitive confirmatory test and KOH the least expensive. The overall cost of an incorrect diagnosis (no confirmatory test used) ranged between $350 and $1175 CAD per patient for treatment of 3 infected toenails. Comparatively, performing confirmatory testing prior to treatment decreases the overall cost to $320 to $930, depending on the therapy, physician, and test.

Conclusions:

It is preferred to diagnose onychomycosis prior to treatment. Furthermore, there are cost savings when confirmatory testing is performed before initiating treatment with both topical and oral antifungals in Canada.

Onychomycosis in the 21st Century: An Update on Diagnosis, Epidemiology, and Treatment

Onychomycosis accounts for 50% of all nail disease cases and is commonly caused by dermatophytes. Diabetes, human immunodeficiency virus, immunosuppression, obesity, smoking, and advancing age are predisposing factors of this fungal infection. Potassium hydroxide and culture are considered the current standard for diagnosing onychomycosis, revealing both fungal viability and species identification. Other diagnostic tests currently available include periodic acid-Schiff staining, polymerase chain reaction techniques, and fluorescent staining. Across 6 recently published epidemiology studies, the global prevalence of onychomycosis was estimated to be 5.5%, falling within the range of previously reported estimates (2%-8%). Newly approved onychomycosis treatments include efinaconazole, tavaborole, and laser therapy with lasers only approved to temporarily increase the amount of clear nail. Additional onychomycosis treatments being investigated include iontophoresis and photodynamic therapy with small open-label studies reported thus far. Preventative strategies, to help decrease recurrence and reinfection rates, include sanitisation of footwear and prophylactic topical antifungal agents.

Nail clipping in onychomycosis

Onychomycosis is the most prevalent onychopathy and it requires a correct early diagnosis. Currently, the diagnostic gold standard is the association of direct mycological test with culture; however, it shows variable sensitivity. The histopathological examination of the distal nail plate, called clipping, has shown to be an adjuvant in diagnosing onychomycosis. This is an easy-to-perform, relatively cheap examination that is little dependent of the examiner, rapidly provides results, has high sensitivity, and for patients it is painless and harmless.

Comparative microscopic analysis of nail clippings from patients with cutaneous psoriasis and psoriatic arthritis

BACKGROUND

The nail involvement in psoriasis is related to psoriatic arthritis and may represent a predictor of the disease.

OBJECTIVES

To analyze, through nail clipping, clinically normal and dystrophic nails of patients with cutaneous psoriasis and psoriatic arthritis.

METHODS

This is a cross-sectional multicenter study, conducted between August 2011 and March 2012. Patients were divided into four groups: patients with cutaneous psoriasis and onychodystrophy, patients with cutaneous psoriasis and clinically normal nails, patients with psoriatic arthritis and onychodystrophy and patients with psoriatic arthritis and clinically normal nails. We calculated NAPSI (Nail Psoriasis Severity Index) of the nail with more clinically noticeable change. After collection and preparation of the nail clipping, the following microscopic parameters were evaluated: thickness of the nail plate and subungual region, presence or absence of parakeratosis, serous lakes, blood, and fungi.

RESULTS

There were more layers of parakeratosis (p=0.001) and a greater thickness of the subungual region in patients with cutaneous psoriasis and onychodystrophy (p=0.002). Serous lakes were also more present in the same group (p=0.008) and in patients with psoriatic arthritis and normal nails (p=0.047). The other microscopic parameters showed no significant difference between normal and dystrophic nails or between patients with psoriatic arthritis or cutaneous psoriasis.

STUDY LIMITATIONS

Small sample size and use of medications.

CONCLUSIONS

Nail clipping is a simple and quick method to assess the nails of patients with nail psoriasis although does not demonstrate difference between those with joint changes or exclusively cutaneous psoriasis.

Meta-analysis of the utility of culture, biopsy, and direct KOH examination for the diagnosis of onychomycosis

Background

Onychomycosis is a highly prevalent disease worldwide. There is no standard test for its diagnosis, which remains costly, wasteful, and is sometimes delayed. The diagnostic tests for this disease are few and discordant. The objective was to evaluate the diagnostic validity, performance, and accuracy of culture, nail clipping with Periodic Acid-Schiff –PAS- staining (biopsy), and direct potassium hydroxide (KOH) examination for the study of onychomycosis.

Methods

A systematic review was conducted via meta-analysis using 5 databases and 21 search strategies. An ex ante protocol was applied with inclusion and exclusion criteria. Quality was assessed with the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool, and the sensitivity, specificity, predictive values, likelihood ratios, diagnostic odds ratios, receiver operating characteristic (ROC) curves, and proportion of correctly diagnosed patients were evaluated with the meta-analysis of studies of evaluations of diagnostic and screening tests (Meta-DiSc) and Epidat using a random effects model.

Results

The efficiency or accuracy of the three tests is influenced by the methodological quality of the studies. These values are lower for KOH and culture and higher for biopsy in moderate quality studies.

Conclusion

The diagnostic tests evaluated in this meta-analysis independently showed acceptable validity, performance, and efficiency, with nail clipping with PAS staining outperforming the other two tests.

Epidemiologic Analysis of Onychomycosis in the San Diego Pediatric Population

BACKGROUND

Onychomycosis (OM) is thought to be a rare disease in children, although there are few epidemiologic studies.

METHODS

This 3-year retrospective case series of nearly 400 children seen at Rady Children's Hospital-San Diego (RCHSD) describes the characteristics of OM found in this pediatric population.

RESULTS

From 2011 to 2013, the Pediatric and Adolescent Dermatology Clinic at RCHSD saw a total of 36,634 unique patients, of whom 433 were unique patients with OM. Thirty-four patients met exclusion criteria, leaving 399 (1.1%) with a diagnosis of OM by a pediatric dermatologist. Nail cultures were obtained in 242 cases (60.7%), 116 (48.0%) of which were positive. Trichophyton rubrum was the most commonly isolated pathogen, responsible for 106 cases (91.3%) of positive cultures in the cohort.

CONCLUSIONS

Our study provides important regional information regarding epidemiologic data in pediatric onychomycosis, highlighting the diagnostic methods most commonly used and the pathogens most frequently encountered in our practice.

Improving Cure Rates in Onychomycosis

Background:

Onychomycosis is a persistent fungal nail infection that is notoriously hard to treat. Approximately 20% to 25% of patients with onychomycosis do not respond to treatment, and 10% to 53% of patients relapse. As such, successful treatment is imperative for long-term disease management.

Objective:

To identify ways to improve cure rates for onychomycosis.

Method:

The literature on onychomycosis treatment and recurrence was reviewed to summarize treatment approaches and suggest strategies to increase cure rates.

Results and Conclusion:

To improve treatment success in onychomycosis, we suggest the following measures be followed: (1) onychomycosis must be correctly diagnosed, (2) the treatment regimen should be tailored to the individual patient, (3) the efficacy of antifungals must be maximized, and (4) recurrence must be prevented.

Laser Therapy for Onychomycosis: Fact or Fiction?

Onychomycosis is a common fungal infection, afflicting some 10% of the adult population in industrialized countries. Aside from cosmetic concerns, onychomycosis can be the cause of toe and foot pain, as well as the underlying etiology for serious secondary bacterial infections and traumatic ulcerations. In select populations, such as diabetics, the latter conditions may even result in loss of all or part of the lower extremity. Thus, a simple, cost-effective and safe treatment for onychomycosis is highly desirable. Although both topical and oral systemic antifungal agents are available for this purpose, they are not always effective, carry some medical risks, are associated with potentially significant drug-drug interactions, and may be unacceptable to patient and healthcare provider alike. Physical modalities, such as laser therapy, therefore appear appealing. The question is whether laser treatment is sufficiently efficacious and safe to warrant the current high cost per treatment. The readily available literature on this controversy will be reviewed herein.

Histopathological examination of nail clippings using PAS staining (HPE-PAS): gold standard in diagnosis of Onychomycosis

Onychomycosis is fungal infection of one or more of the nail units. However, because fungi cause only about half of all nail dystrophies, the use of appropriate diagnostic techniques is important to ensure correct diagnosis and treatment. Aim of the present study was to compare direct microscopy, culture and HPE-PAS for diagnosis of onychomycosis by evaluating their sensitivity and various other relevant statistical parameters. A prospective, hospital-based, cross-sectional study was conducted on 216 patients with a high degree of clinical suspicion of onychomycosis. Nail specimens were evaluated using three diagnostic methods, i.e. direct microscopy using 20% Potassium hydroxide (KOH) & 40% Di-methyl-suphoxide (DMSO), culture and histopathological examination using PAS stain (HPE-PAS). Of 216 patients direct microscopy was positive in 138 (63.9%), culture in 147 (68%) and HPE-PAS in 164 patients (76%). One hundred and seventy-nine patients fitted into the criteria set for confirmed diagnosis of onychomycosis. Using this as a denominator; direct microscopy, culture and HPE-PAS had sensitivities of 77.1%, 70% and 91.6% respectively. Also, HPE-PAS showed the highest sensitivity of 94.7% in 19 cases with prediagnostic antimycotic treatment compared to direct microscopy (42.1%) or culture (57.9%). HPE-PAS shows high sensitivity for diagnosis of onychomycosis and can be considered as a gold standard in the diagnosis of onychomycosis.

Processing dermatological biopsies

Dermatological biopsies can be obtained from many anatomic areas and fulfill a variety of diagnostic roles. Due to this variety, the handling and processing of dermatological specimens pose unique challenges. The small size, disparate shapes, and anatomic variation seen on skin biopsies require specialized techniques to enable sufficient sampling, proper orientation, and accurate diagnoses. This chapter addresses issues related specifically to the processing of small specimens, evaluation for biopsies for alopecia, nail specimens, frozen sections, and specimens requiring direct immunofluorescence.

Microscopic examination of normal nail clippings

BACKGROUND

Nail clipping analysis for diagnosing causes of onychodystrophy other than onychomycosis is investigated to a very small extent. In order to achieve acceptance as a diagnostic method for any kind of nail abnormalities, normal microscopic parameters have to be established first. In most reported cases, nail plates were fixed in formalin with processing of the specimens with routine automated histotechnique.

METHODOLOGY

Fifteen pairs of normal nails were studied. One nail fragment was placed in a container with formalin, and the other was kept dry in a proper receptacle. Fixed specimens were submitted to standard automated tissue processing (formalin group) and dry specimens were directly embedded in paraffin (dry group). Several microscopic parameters were analyzed.

RESULTS

Nail plate thickness ranged from 0.25 to 0.50 mm (mean 0.36 mm) and subungual region from 0 to 0.31 mm (mean 0.11 mm). Forty-one percent of cases presented onychokaryosis, and hypereosinophilic nuclear shadows were detected in 63%, statistically more frequent in the dry group (p=0.002). Parakeratosis was present in 86% of nails varying from 1 to 13 layers (mean 5.6). None of the nails presented fungi, neutrophils, and blood or serum collections. Bacteria were seen in 60% of specimens. Both groups yielded adequate microscopic preparations for analysis with no statistical difference in the dryness or hardness of specimens or difficulty in cutting the paraffin blocks (p=1).

CONCLUSION

These microscopic findings of a normal population can be used as parameters for evaluating any cause of onychodystrophy. The dry method is faster and cheaper and yields adequate slide preparations for microscopic analysis of nail clippings.

Nail histopathology

The structure of the nail unit is complex and many dermatologists and dermatopathologists have an incomplete understanding of it. Familiarity with the anatomy and histology of this unit, however, is a key factor in improving the diagnostic yield of nail biopsy. Inflammatory or infectious conditions that affect the nail can have a marked impact on a patient's quality of life. A wide-ranging variety of tumors can also develop in this region and they may be life-threatening or require surgery that will result in functional defects. The author reviews the anatomy and histology of the nail unit as well as the basic histopathologic findings in the most common conditions affecting the nails.

[New apects in the diagnosis and therapy of dermatomycoses]

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.