Histopathological periodic acid-schiff stains of nail clippings as a second-line diagnostic tool in onychomycosis

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.

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.

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.

Neutrophils in Nail Clipping Histology: A Retrospective Review of 112 Cases

BACKGROUND

Nail clipping histology is more sensitive than mycology for detecting nail fungi. However, in the absence of fungi, established diagnostic clues for this and other nail dystrophy causes are lacking, namely for nail psoriasis. Neutrophils have been reported in onychomycosis and nail psoriasis samples but have been insufficiently characterized.

OBJECTIVES

The aim of this paper is to differentiate neutrophil-containing nail clipping samples in nail psoriasis and onychomycosis regarding histology.

METHODS

We performed a 3-year retrospective review of all nail clipping test results included in our department's database and re-analyzed samples containing neutrophils.

RESULTS

In total,112 neutrophil-containing nail clipping samples were accounted. Onychomycosis was the commonest diagnosis (74.1%), followed by nail psoriasis (18.8%). Onychomycosis samples had more abundant neutrophils, more often arranged in collections (60.2%) (p = 0.002) and with smaller quantities of parakeratosis, in a lamellar distribution. In nail psoriasis, neutrophils were mostly aggregated (57.1%) with parakeratosis in all samples, in increased amounts, and showing no predominant pattern.

CONCLUSIONS

Neutrophils are present in both nail psoriasis and onychomycosis, warranting careful interpretation. However, less dense aggregates of neutrophils with more abundant parakeratosis are clues of nail psoriasis when all other fungal tests are negative.

[Relevance of biopsies for the diagnostics of infectious skin diseases]

Pathogen-related skin infections are a common problem in the dermatological practice. Apart from culturing and serological detection methods, a skin biopsy is a possible diagnostic procedure, especially when the clinical picture is unspecific and other non-infectious skin diseases are considered as possible differential diagnoses. Some organisms can already be detected by routine staining methods (hematoxylin & eosin, e. g., yeasts, Leishmania), for others numerous histochemical and immunohistochemical stains are available, e. g. periodic acid-Schiff reaction (PAS) and Grocott for hyphae and spores, Ziehl-Neelson and Fite-Faraco for Mycobacteria or specific antibodies for Treponema pallidum or herpesviruses. In other instances, an infectious disease may not be diagnosed with certainty in a histological section but the pattern of inflammatory infiltrates is highly suggestive of an infectious cause. Based on such reaction patterns, the dermatopathologist can advise the clinician to perform cultures or serological investigations or additional molecular biological techniques can be applied to the biopsy specimen in order to identify the pathogens. This article presents skin infections with their histopathological features and highlights diseases that can be diagnosed with certainty in a biopsy and those in which a biopsy is helpful to exclude differential diagnoses or to perform molecular diagnostics on the specimen.

Examen mycologique en dermatologie

Dermatomycoses are dermatological infections very commonly encountered in private dermatological practice since they affect up to one third of the population. However, the symptoms are very often shared by other skin infections and disorders and may be highly atypical. It is thus impossible to make a diagnosis with any certainty on clinical grounds alone. For this reason, mycological diagnosis is essential to either confirm or rule out dermatomycosis, and is unavoidable when antifungal therapy is required for the treatment of ringworm of the scalp or beard, or for onychomycosis. It is also vital where therapy guided by the clinical appearance of lesions has failed or in the event of recurring skin lesions. Confirmation of mycosis enables antifungals to be initiated and a negative test warrants investigation for other underlying causes for the lesions seen. However, regardless of the mycological diagnostic technique employed, the quality of the results depends chiefly on the quality of sampling of the infected site, but also on the expertise of the microbiologist. Standard mycological testing remains the most informative, the least expensive and the sole examination capable of isolating the causative fungus irrespective of the type of mycosis, such as dermatophytosis, scytalidiosis, mould-induced ungual infection, candidiasis, or infections due to Malassezia sp. This is the only examination able to identify epidemiological variations. All other more recent techniques are either based upon simple demonstration of the fungal elements involved, without identification of the fungal species in question, or else they are reliant upon a fungal database that is generally highly incomplete.

Tinea Unguium: Diagnosis and Treatment in Practice

Onychomycosis is caused by dermatophytes, yeasts or non-dermatophyte molds; when caused by dermatophytes, it is called tinea unguium. The main etiological agents are Trichophyton rubrum and Trichophyton interdigitale. The most frequent types are distal and lateral subungual onychomycosis. Diagnosis usually requires mycological laboratory confirmation. Dermoscopy can be helpful and also biopsy is an excellent diagnostic method in uncommon cases or when mycological test is negative. Treatment must be chosen according to clinical type, number of affected nails and severity. The goal for antifungal therapy is the clearing of clinical signs or mycological cure.

Randomized, double-blind, comparative study on efficacy and safety of itraconazole pulse therapy and terbinafine pulse therapy on nondermatophyte mold onychomycosis: A study with 90 patients

BACKGROUND

Nondermatophyte mold (NDM) onychomycosis shows poor response to current topical, oral or device-related antifungal therapies. This study was aimed to determine the efficacy and safety of itraconazole and terbinafine pulse therapy on NDM onychomycosis.

METHODS

Mycologically proven subjects were treated with itraconazole 400 mg daily or terbinafine 500 mg daily for 7 days/month; two pulses for fingernails and three pulses for toenails(SLCTR/2013/013).

RESULTS

One-hundred seventy-eight patients underwent mycological studies and 148 had positive fungal isolates. NDM were the prevailing fungi, 68.2%, followed by candida species 21.6%, and dermatophytes made up only 10.1%. Out of NDM Aspergillus spp (75.1%) predominated followed by 8.9% Fusarium spp and 4.95% Penicillium spp. The clinical cure at completion of pulse therapy was statistically significant 9.2% versus 2.0% (p < 0.05) in itraconazole group. But no statistically significant difference was detected between the two regimens at the end of 12 months; 65.1% versus 54.64%. Recurrences observed in both groups (6.5% vs. 4.1%) were not statistically significant. With itraconazole pulse 68.22% Aspergillus spp, 50.0% Fusarium spp and 84.6% Penicillium spp showed clinical cure, while terbinafine pulse cured 55.0% Aspergillus spp and 50.0% Fusarium spp.

CONCLUSIONS

NDM was the prevailing fungi in onychomycosis in Sri Lanka. Both itraconazole and terbinafine were partially effective on NDM onychomycosis showing a clinical cure of 54-65%. Future research should focus on searching more effective antifungal for NDM onychomycosis.

Angiogenic Effect of Bioactive Borate Glass Microfibers and Beads in the Hairless Mouse

The purpose of this project was to investigate the angiogenic mechanism of bioactive borate glass for soft tissue repair in a ‘hairless’ SKH1 mouse model. Subcutaneous microvascular responses to bioactive glass microfibers (45S5, 13-93B3, and 13-93B3Cu) and bioactive glass beads (13-93, 13-93B3, and 13-93B3Cu) were assessed via: noninvasive imaging of skin microvasculature; histomorphometry of microvascular densities; and quantitative PCR measurements of mRNA expression of VEGF and FGF-2 cytokines. Live imaging via dorsal skin windows showed the formation at twoweeks of a halo-like structure infused with microvessels surrounding implanted boratebased 13-93B3 and 13-93B3Cu glass beads, a response not observed with silicate-based 13-93 glass beads. Quantitative histomorphometry of tissues implanted with plugs of 45S5, 13-93B3, and 13-93B3Cu glass microfibers revealed microvascular densities that were 1.6-, 2.3-, and 2.7-times higher, respectively, than the sham control valueswhereas 13-93, 13-93B3, and 13-93B3Cu glass beads caused the microvascular density to increase 1.3-, 1.6-, and 2.5-fold, respectively, relative to sham controls. Quantitative PCR measurements indicate a marginally significant increased expression of VEGF mRNA in tissues with 13-93B3Cu glass beads, an outcome that supported the hypothesis that copper-doped borate glass could promote VEGF expression followed by angiogenesis for enhanced wound healing.

Rapid detection of dermatophytes and Candida albicans in onychomycosis specimens by an oligonucleotide array

Background

Onychomycosis is a fungal infection of nails, leading to the gradual destruction of the nail plate. Treatment of onychomycosis may need long-time oral antifungal therapy that can have potential side effects, thus accurate diagnosis of the disease before treatment is important. Culture for diagnosis of onychomycosis is time-consuming and has high false-negative rates. To expedite the diagnosis, an oligonucleotide array, based on hybridization between immobilized oligonucleotide probes and PCR products, for direct detection of dermatophytes and Candida albicans in clinical specimens was evaluated.

Methods

Species-specific oligonucleotide probes designed from the internal transcribed spacer (ITS) regions of the rRNA gene were immobilized on a nylon membrane. The assay procedures consisted of PCR amplification of the ITS using universal primers, followed by hybridization of the digoxigenin-labeled amplicons to probes on the array. Thirty two nail samples (29 patients) were analyzed by the array, and the results were compared with those obtained by culture. Array-positive but culture-negative samples were confirmed by cloning and re-sequencing of the amplified ITS and by reviewing patient’s clinical data. The total recovery of culture and confirmed array-positive but culture-negative results was considered 100% and was used for performance evaluation of both methods.

Results

Concordant results were obtained in 21 samples (10 positives and 11 negatives) by both methods. Eleven samples were array-positive but culture-negative; among them, 9 samples were considered true positives after discrepant analysis. Comparing with culture, the array had significantly higher sensitivity [100% (95% CI 82.2% −100%) vs 52.6% (28.9% −75.5%), p <0.001] and negative predictive value [100% (71.3% −100%) vs 59.1% (36.4% −79.3%), p <0.05), while no significant differences were observed in specificity (84.6% vs 100%, p =0.48) and positive predictive value (90.5% vs 100%, p =1.0). The whole procedures of the array were about 24 h, whilst results from culture take 1 to 3 weeks.

Conclusions

The array offers an accurate and rapid alternative to culture. Rapid diagnosis can expedite appropriate antifungal treatment of onychomycosis. However, the single site nature of this study conducted at a referral hospital invites caution.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0581-5) contains supplementary material, which is available to authorized users.

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.

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.