Diagnostic reliability of the Tzanck smear in dermatologic diseases

Classic bedside diagnostic techniques

Correctly performing bedside diagnostic tests is an important fundamental skill for practicing dermatologists. Even with new technologies, bedside diagnostic tests have been useful in contemporary practice. When properly implemented, bedside diagnostic techniques can efficiently and economically aid in diagnosis and treatment. We have reviewed the most commonly used diagnostic procedures while considering them in their historical context, outlined the procedures for performing the tests, and discussed the relevance and regulatory requirements of the tests.

Current status and prospects for the diagnosis of pemphigus vulgaris

Introduction: Pemphigus vulgaris (PV) is an intraepidermal autoimmune bullous disease (AIBD) characterized by autoantibodies against desmosomal adhesion proteins, most commonly desmoglein (Dsg)3, leading to the suprabasal cleft formation and acantholysis.Areas covered: Direct immunofluorescence (DIF) and indirect immunofluorescence (IIF) studies display the intercellular deposition of IgG/C3 throughout the epidermis and presence of circulating autoantibodies respectively, as a net-like pattern. However, the target antigen remains unknown using immunofluorescence techniques. Thanks to the development of Dsg ELISA, using recombinant technology, circulating antibodies against Dsg1 and 3 could be detected sensitively. It is possible to differentiate PV from pemphigus foliaceus (PF) using this assay. BIOCHIP mosaic and multivariant ELISA are two novel serologic methods with the added value of the ability to screen several AIBDs simultaneously.Non-Dsg1/3 antigens are also involved in the pathogenesis of PV and investigated more deeply thanks to the protein microarrays technique. Additionally, patients with high values of anti-Dsg1/3 may be lesion-free, suggesting the presence of nonpathogenic autoantibodies.Expert opinion: Newer diagnostic methods to replace traditional techniques should possess high sensitivity and specificity and be widely available, noninvasive, and relatively cheap. The newly developed methods need to be further evaluated before being recommended for routine use.

Detection of multinucleated giant cells in differentiated keratinocytes with herpes simplex virus and varicella zoster virus infections by modified Tzanck smear method

Herpes simplex virus (HSV) and varicella zoster virus (VZV) infections induce the formation of intraepidermal vesicles containing acantholytic cells and multinucleated giant cells in the skin. The Tzanck smear is most commonly used to diagnose cutaneous herpetic infections, but it leads to many false-positive and -negative results. This study aimed at establishing a method detecting much larger multinucleated giant cells using the Tzanck smear because these cells characterize the viral cytopathic effect in skin infections. Morphological changes were analyzed among several layers of keratinocytes with HSV- or VZV-related cutaneous lesions, clinically and in vitro. We compared the sensitivity of the Tzanck smear to detect large acantholytic cells using both the removed roof tissue part (our approach) and the floor of the lesion (conventional approach) of a fresh vesicle. Large acantholytic cells were detected 2.0-times more frequently in the removed roof tissue part of the vesicle than in the floor of the lesion. Round cells were much larger in the removed roof tissue part of the vesicle corresponding to the granular or prickle layer of the epidermis than in its floor of the lesion corresponding to the basal or prickle layer with the Tzanck smear. Differentiated cultured keratinocytes formed multinucleated giant cells by cell-to-cell fusion with resolution of cell membrane with VZV infection. Differentiated keratinocytes promote multinucleated giant cell formation by cell-to-cell fusion with HSV-1 or VZV infection. To increase the sensitivity, the Tzanck smear should be prepared from the removed roof tissue part of a fresh vesicle to detect multinucleated giant cells in herpetic infections.

Diagnostic value of cytology in oral ulcer and comparison with histopathology and direct immunofluorescence

Rapid diagnosis of pemphigus vulgaris (PV) is an important task in patient's prognosis and treatment. Although PV is routinely diagnosed through investigation of pathology specimens and direct immunofluorescence assays, Tzanck smear can be used as rapid, inexpensive, and easily used test to confirm its clinical diagnosis. This study aimed to determine the diagnostic value of Tzanck smear in erosive oral lesions of PV and also determine its sensitivity and specificity for diagnostic purposes. A total of 68 patients with erosive/ulcerated oral lesions were included in this study and divided into PV (case group) vs other causes of erosive oral lesions (control group). From all participants, two Tzanck smears were prepared for both Giemsa and hematoxylin-eosin (H&E) staining. For definite diagnosis, histopathology and direct immunofluorescence evaluations were performed based on clinical findings. The sensitivity of acantholytic cells in Tzanck smear of erosive oral lesions of PV cases was 80.5% (for both Giemsa and H&E staining), whereas specificity values of Giemsa and H&E staining were 84.6% and 96.3%, respectively. Based on our findings, the Tzanck smear of erosive oral lesions is a simple, quick, and inexpensive test for screening and primary diagnosis of PV.

Exfoliative cytology for diagnosing basal cell carcinoma and other skin cancers in adults

BACKGROUND

Early accurate detection of all skin cancer types is essential to guide appropriate management, reduce morbidity and improve survival. Basal cell carcinoma (BCC) is usually localised to the skin but has potential to infiltrate and damage surrounding tissue, while cutaneous squamous cell carcinoma (cSCC) and melanoma have a much higher potential to metastasise and ultimately lead to death. Exfoliative cytology is a non-invasive test that uses the Tzanck smear technique to identify disease by examining the structure of cells obtained from scraped samples. This simple procedure is a less invasive diagnostic test than a skin biopsy, and for BCC it has the potential to provide an immediate diagnosis that avoids an additional clinic visit to receive skin biopsy results. This may benefit patients scheduled for either Mohs micrographic surgery or non-surgical treatments such as radiotherapy. A cytology scrape can never give the same information as a skin biopsy, however, so it is important to better understand in which skin cancer situations it may be helpful.

OBJECTIVES

To determine the diagnostic accuracy of exfoliative cytology for detecting basal cell carcinoma (BCC) in adults, and to compare its accuracy with that of standard diagnostic practice (visual inspection with or without dermoscopy). Secondary objectives were: to determine the diagnostic accuracy of exfoliative cytology for detecting cSCC, invasive melanoma and atypical intraepidermal melanocytic variants, and any other skin cancer; and for each of these secondary conditions to compare the accuracy of exfoliative cytology with visual inspection with or without dermoscopy in direct test comparisons; and to determine the effect of observer experience.

SEARCH METHODS

We undertook a comprehensive search of the following databases from inception up to August 2016: Cochrane Central Register of Controlled Trials; MEDLINE; Embase; CINAHL; CPCI; Zetoc; Science Citation Index; US National Institutes of Health Ongoing Trials Register; NIHR Clinical Research Network Portfolio Database; and the World Health Organization International Clinical Trials Registry Platform. We also studied the reference lists of published systematic review articles.

SELECTION CRITERIA

Studies evaluating exfoliative cytology in adults with lesions suspicious for BCC, cSCC or melanoma, compared with a reference standard of histological confirmation.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted all data using a standardised data extraction and quality assessment form (based on QUADAS-2). Where possible we estimated summary sensitivities and specificities using the bivariate hierarchical model.

MAIN RESULTS

We synthesised the results of nine studies contributing a total of 1655 lesions to our analysis, including 1120 BCCs (14 datasets), 41 cSCCs (amongst 401 lesions in 2 datasets), and 10 melanomas (amongst 200 lesions in 1 dataset). Three of these datasets (one each for BCC, melanoma and any malignant condition) were derived from one study that also performed a direct comparison with dermoscopy. Studies were of moderate to poor quality, providing inadequate descriptions of participant selection, thresholds used to make cytological and histological diagnoses, and blinding. Reporting of participants' prior referral pathways was particularly poor, as were descriptions of the cytodiagnostic criteria used to make diagnoses. No studies evaluated the use of exfoliative cytology as a primary diagnostic test for detecting BCC or other skin cancers in lesions suspicious for skin cancer. Pooled data from seven studies using standard cytomorphological criteria (but various stain methods) to detect BCC in participants with a high clinical suspicion of BCC estimated the sensitivity and specificity of exfoliative cytology as 97.5% (95% CI 94.5% to 98.9%) and 90.1% (95% CI 81.1% to 95.1%). respectively. When applied to a hypothetical population of 1000 clinically suspected BCC lesions with a median observed BCC prevalence of 86%, exfoliative cytology would miss 21 BCCs and would lead to 14 false positive diagnoses of BCC. No false positive cases were histologically confirmed to be melanoma. Insufficient data are available to make summary statements regarding the accuracy of exfoliative cytology to detect melanoma or cSCC, or its accuracy compared to dermoscopy.

AUTHORS' CONCLUSIONS

The utility of exfoliative cytology for the primary diagnosis of skin cancer is unknown, as all included studies focused on the use of this technique for confirming strongly suspected clinical diagnoses. For the confirmation of BCC in lesions with a high clinical suspicion, there is evidence of high sensitivity and specificity. Since decisions to treat low-risk BCCs are unlikely in practice to require diagnostic confirmation given that clinical suspicion is already high, exfoliative cytology might be most useful for cases of BCC where the treatments being contemplated require a tissue diagnosis (e.g. radiotherapy). The small number of included studies, poor reporting and varying methodological quality prevent us from drawing strong conclusions to guide clinical practice. Despite insufficient data on the use of cytology for cSCC or melanoma, it is unlikely that cytology would be useful in these scenarios since preservation of the architecture of the whole lesion that would be available from a biopsy provides crucial diagnostic information. Given the paucity of good quality data, appropriately designed prospective comparative studies may be required to evaluate both the diagnostic value of exfoliative cytology by comparison to dermoscopy, and its confirmatory value in adequately reported populations with a high probability of BCC scheduled for further treatment requiring a tissue diagnosis.

Bedside diagnostics in dermatology: Parasitic and noninfectious diseases

In addition to aiding the diagnosis of viral, bacterial, and fungal diseases, mineral oil preparation, Tzanck smear, and other techniques can be used to diagnose parasitic infections, neonatal pustular dermatoses, blistering diseases, Stevens-Johnson syndrome, and a plethora of other benign and malignant conditions, including granulomatous diseases and tumors. In many cases, these techniques are specific, reliable, and easy to perform and interpret. In others, a certain amount of training and expertise are required. In the proper clinical scenario, these tests are rapid, economical, and compare favorably with other diagnostic methods.

Bedside diagnostics in dermatology: Viral, bacterial, and fungal infections

Viral, bacterial, and fungal infections are frequently encountered in clinical practice, resulting in numerous cutaneous manifestations. Although diagnosis of these infections has changed over time because of technological advancements, such as polymerase chain reaction, bedside diagnostic techniques still play an important role in diagnosis and management, enabling rapid and low-cost diagnosis and implementation of appropriate therapies. This 2-part article will review both common and infrequent uses of bedside diagnostic techniques that dermatologists can incorporate into daily practice. This article examines the utility of bedside tests for the diagnosis of viral, bacterial, and fungal infections. The second article in this series reviews the use of bedside diagnostics for parasitic and noninfectious disorders.

Diagnostic Utility and Pitfalls of Tzanck Smear Cytology in Diagnosis of Various Cutaneous Lesions

Aims:

Tzanck smear is an old but useful test for diagnosis of cutaneous dermatoses. The aim of this study was to highlight the potential usefulness and diagnostic pitfalls of Tzanck smear for diagnosis of cutaneous dermatoses and infections.

Materials and Methods:

This hospital based cross-sectional study was carried out on all Tzanck smears received for a period of twenty months (January 2014–August 2015). The smears were assessed to establish the utility of Tzanck smears in corroborating or excluding a diagnosis of immunobullous lesion or herpetic infection. Cases with discrepant diagnosis on histopathology were reviewed to identify additional cytomorphological features.

Results:

A total of 57 Tzanck smears were performed during the study period. Out of the 18 clinically suspected cases of immunobullous disorders, Tzanck smear findings corroborated the clinical diagnosis in 7/18 cases, one case was diagnosed as cutaneous candidiasis, and diagnosis of immunobullous lesions could be excluded in 5/18 cases. Out of the 19 suspected cases of herpetic infections, viral cytopathic effect was observed in 8/19 cases. Besides immunobullous lesions and herpetic infections, acantholytic cells were also observed in spongiotic dermatitis and genodermatosis. Dyskeratotic keratinocytes seen in vacuolar interface dermatitis were not easily distinguishable from acantholytic cells on Tzanck smear.

Conclusions:

Tzanck smear test is an inexpensive and useful diagnostic tool for certain skin diseases. It can aid in establishing a rapid clinical diagnosis and can serve as a useful adjunct to routine histological examination. We recommend the use of Tzanck smear as a first-line investigation for vesiculobullous, erosive, and pustular lesions.

Distal Interphalangeal Joint Arthrodesis Complicated by Postoperative Infection: A Rare Presentation of Disseminated Herpes Simplex Virus

Postoperative infection after elective arthrodesis of the interphalangeal joint is an uncommon complication often necessitating urgent debridement. We present the rare case of a female patient with a history of oral herpetic lesions, who underwent elective arthrodesis of the middle and index fingers for treatment of erosive osteoarthritis and subsequently developed a postoperative herpetic infection at the surgical site.

Diagnostic value of telecytology in tertiary teledermatological consultation: a retrospective analysis of 75 cases

BACKGROUND

The addition of dermatoscopic images to clinical images is reported to increase the diagnostic value of teledermatology. No study has investigated the contribution of telecytology to teledermatology. We aimed to assess the diagnostic accuracy of telecytology in tertiary teledermatological evaluation.

METHODS

The study included 75 patients for whom no diagnosis could be established at face-to-face clinical examinations and cytological evaluations, who therefore consulted with a dermatologist experienced in cytology through the store-and-forward method. Telecytological diagnosis was then compared with the final diagnosis, and diagnostic accuracy was calculated.

RESULTS

In the past 2 years, 75 patients (38 [50.7%] female, 37 [49.3%] male) were evaluated by telecytology. According to definitive diagnoses, 31 patients (41.3%) had erosive-vesiculobullous, 25 (33.3%) had tumoral, and 19 (15.8%) had granulomatous disease. Diagnostic accuracy of telecytology was 90.7%.

LIMITATIONS

Our study was a retrospective study, and cytological images were evaluated by one dermatologist only; therefore, no reliability analysis could be performed.

CONCLUSION

This study revealed that the cytological images should be used in tertiary teledermatological evaluation. Further studies should therefore be carried out to investigate the diagnostic value of different telecytological methods.

Diagnostic value of Tzanck smear in various erosive, vesicular, and bullous skin lesions

Background:

Cutaneous cytology has long been shown to be useful in the diagnosis of several erosive, vesicular, and bullous skin lesions. The Tzanck smear although an old tool, still remains a simple, rapid, easily applied, and inexpensive test for these skin lesions.

Aims and Objectives:

The aim of this study was to evaluate the diagnostic value of Tzanck smear by determining its sensitivity and specificity in various erosive, vesicular, and bullous skin lesions.

Materials and Methods:

One hundred and forty-two patients with erosive, vesicular, and/or bullous skin lesions were included in the study. Four groups of disorders were identified: infections, immunologic disorders, genodermatosis, and spongiotic dermatitis. All the study cases were evaluated by Tzanck smear. Definitive diagnosis was established by standard diagnostic techniques (including when appropriate, viral serology, bacterial culture, histopathology, direct immunoflourescence).

Results:

The sensitivity and specificity of cytologic findings was respectively 86.36% and 91.30% for viral infections; for bacterial infections, it was 85.7% and 66.6%. The sensitivity and specificity of Tzanck smear was respectively 85.0% and 83.33% for pemphigus; for bullous pemhigoid it was 11.11% and 100.0%. Tzanck smear sensitivity in genodermatoses was 100%. The sensitivity and specificity of the test in spongiotic dermatitis could not be calculated due to an insufficient number of patients.

Conclusion:

The Tzanck smear is a quick and reliable tool for the evaluation of various erosive and vesiculobullous skin lesions.