Interobserver reproducibility of histological features in cutaneous malignant melanoma

Advantages of manual and automatic computer-aided compared to traditional histopathological diagnosis of melanoma: A pilot study

BACKGROUND

Cutaneous malignant melanoma (CMM) accounts for the highest mortality rate among all skin cancers. Traditional histopathologic diagnosis may be limited by the pathologists' subjectivity. Second-opinion strategies and multidisciplinary consultations are usually performed to overcome this issue. An available solution in the future could be the use of automated solutions based on a computational algorithm that could help the pathologist in everyday practice. The aim of this pilot study was to investigate the potential diagnostic aid of a machine-based algorithm in the histopathologic diagnosis of CMM.

METHODS

We retrospectively examined excisional biopsies of 50 CMM and 20 benign congenital compound nevi. Hematoxylin and eosin (H&E) stained WSI were reviewed independently by two expert dermatopathologists. A fully automated pipeline for WSI processing to support the estimation and prioritization of the melanoma areas was developed.

RESULTS

The spatial distribution of the nuclei in the sample provided a multi-scale overview of the tumor. A global overview of the lesion's silhouette was achieved and, by increasing the magnification, the topological distribution of the nuclei and the most informative areas of interest for the CMM diagnosis were identified and highlighted. These silhouettes allow the histopathologist to discriminate between nevus and CMM with an accuracy of 96% without any extra information.

CONCLUSION

In this study we proposed an easy-to-use model that produces segmentations of CMM silhouettes at fine detail level.

Mitotic rate in primary melanoma: interobserver and intraobserver reliability, analyzed using H&E sections and immunohistochemistry

BACKGROUND

In 2009, the AJCC issued a revised melanoma staging system. In addition to tumor thickness and ulceration, the mitotic rate was introduced as the third major prognostic parameter for the classification of primary cutaneous melanoma. Given that, according to the 2009 AJCC classification, the detection of one or more dermal tumor mitoses leads to an upstaging - from stage Ia to Ib - of melanomas with a tumor thickness of ≤ 1.0 mm, we set out to investigate the reproducibility of this new parameter.

METHODS

In order to assess interobserver reliability, 17 dermatopathologists und pathologists - all well versed in the diagnosis of cutaneous melanoma - analyzed the mitotic rate in 15 thin primary cutaneous melanomas (mean tumor thickness 0.91 mm) using identical slides. Mitotic rates were determined on H&E and phosphohistone H3 (Ser10)-stained samples. Without knowledge of their previous assessment, five of the aforementioned examiners reevaluated the samples after more than one year in order to ascertain intraobserver reliability.

RESULTS

Interobserver reliability of the mitotic rate in thin primary melanomas is disappointing and independent of whether H&E or immunohistochemically stained samples are used (kappa value: 0.088 [H&E], 0.154 [IH], respectively). Kappa values improved to 0.345 (H&E) and 0.403 (IH) when using a cutoff of 0/1 vs. 2+ mitoses. Similarly unsatisfactory, kappa values for intraobserver reliability ranged from 0.18 and 0.348, depending on the individual examiner.

DISCUSSION

Given the unsatisfactory reproducibility and large variations in assessing the mitotic rate, it remains a matter of debate whether this diagnostic parameter should play a role in therapeutic decisions.

Diagnostic Accuracy of Virtual Pathology vs Traditional Microscopy in a Large Dermatopathology Study

Importance

Digital pathology represents a transformative technology that impacts dermatologists and dermatopathologists from residency to academic and private practice. Two concerns are accuracy of interpretation from whole-slide images (WSI) and effect on workflow. Studies of considerably large series involving single-organ systems are lacking.

Objective

To evaluate whether diagnosis from WSI on a digital microscope is inferior to diagnosis of glass slides from traditional microscopy (TM) in a large cohort of dermatopathology cases with attention on image resolution, specifically eosinophils in inflammatory cases and mitotic figures in melanomas, and to measure the workflow efficiency of WSI compared with TM.

Design, Setting, and Participants

Three dermatopathologists established interobserver ground truth consensus (GTC) diagnosis for 499 previously diagnosed cases proportionally representing the spectrum of diagnoses seen in the laboratory. Cases were distributed to 3 different dermatopathologists who diagnosed by WSI and TM with a minimum 30-day washout between methodologies. Intraobserver WSI/TM diagnoses were compared, followed by interobserver comparison with GTC. Concordance, major discrepancies, and minor discrepancies were calculated and analyzed by paired noninferiority testing. We also measured pathologists' read rates to evaluate workflow efficiency between WSI and TM. This retrospective study was caried out in an independent, national, university-affiliated dermatopathology laboratory.

Main Outcomes and Measures

Intraobserver concordance of diagnoses between WSI and TM methods and interobserver variance from GTC, following College of American Pathology guidelines.

Results

Mean intraobserver concordance between WSI and TM was 94%. Mean interobserver concordance was 94% for WSI and GTC and 94% for TM and GTC. Mean interobserver concordance between WSI, TM, and GTC was 91%. Diagnoses from WSI were noninferior to those from TM. Whole-slide image read rates were commensurate with WSI experience, achieving parity with TM by the most experienced user.

Conclusions and Relevance

Diagnosis from WSI was found equivalent to diagnosis from glass slides using TM in this statistically powerful study of 499 dermatopathology cases. This study supports the viability of WSI for primary diagnosis in the clinical setting.

An Infrared Absorbance Sensor for the Detection of Melanoma in Skin Biopsies

An infrared (IR) absorbance sensor has been designed, realized and tested with the aim of detecting malignant melanomas in human skin biopsies. The sensor has been designed to obtain fast measurements (80 s) of a biopsy using a small light spot (0.5 mm in diameter, typically five to 10 times smaller than the biopsy size) to investigate different biopsy areas. The sensor has been equipped with a monochromator to record the whole IR spectrum in the 3330-3570 nm wavelength range (where methylene and methyl stretching vibrations occur) for a qualitative spectral investigation. From the collected spectra, the CH₂ stretch ratio values (ratio of the absorption intensities of the symmetric to asymmetric CH₂ stretching peaks) are determined and studied as a cancer indicator. Melanoma areas exhibit different spectral shapes and significantly higher CH₂ stretch ratios when compared to healthy skin. The results of the infrared investigation are compared with standard histology. This study shows that the IR sensor is a promising supportive tool to improve the diagnosis of melanoma during histopathological analysis, decreasing the risk of misdiagnosis.

Mitoserate beim primären Melanom: Interobserver- und Intraobserver-Reproduzierbarkeit am HE-Schnitt und in der Immunhistologie

HINTERGRUND

Die Melanomklassifikation wurde 2009 durch die AJCC revidiert. Für die Klassifizierung primärer Melanome wurde als dritte Größe neben Tumordicke und Ulzeration die Angabe der Mitoserate neu eingeführt. Gemäß der AJCC-2009-Klassifikation des Melanoms führt der Nachweis nur einer oder mehrerer dermaler Tumormitosen bei Melanomen ≤ 1,0 mm Tumordicke zu einer Umgruppierung des Tumors von T1a nach T1b. Dies erklärt, wie wichtig die Frage nach der Reproduzierbarkeit dieses neuen Parameters ist.

METHODEN

Zur Prüfung der Interobserver-Reproduzierbarkeit der Mitoserate haben 17 Dermatopathologen und Pathologen, die in der Befundung des kutanen Melanoms sehr erfahren sind, die Mitoserate in 15 dünnen Melanomen mit einer mittleren Tumordicke von 0,91 mm an demselben Tumorschnitt bestimmt. Die Mitoserate wurde am HE-Schnitt und immunhistologisch (IH) mittels des mitosespezifischen Antikörpers Phospho-Histon-H3 (Ser10) bestimmt. Fünf Befunder wiederholten die Bestimmung nach mehr als einem Jahr ohne Kenntnis ihres Vorbefundes zur Ermittlung der Intraobserver-Reproduzierbarkeit.

ERGEBNISSE

Die Interobserver-Reproduzierbarkeit der Mitoserate bei dünnen Melanomen ist unbefriedigend und unabhängig davon, ob die Mitoserate am HE-Schnitt oder am immungefärbten Schnitt bestimmt wird (κ-Werte: 0,088 [HE] bzw. 0,154 [IH]). Bei einer Diskriminationsschwelle von 0/1 vs. 2+ Mitosen verbesserte sich der κ-Wert auf 0,345 (HE) bzw. 0,403 (IH). Die Intraobserver-Reproduzierbarkeit lag mit κ-Werten zwischen 0,18 und 0,348 je nach Befunder ebenfalls im unbefriedigenden Bereich.

DISKUSSION

Wegen der unbefriedigenden Reproduzierbarkeit und der großen Variation der Befunde zur Mitoserate bleibt es zweifelhaft, ob dieser Befund als Grundlage für Therapieentscheidungen herangezogen werden kann.

Invited Review Article: Pump-probe microscopy

Multiphoton microscopy has rapidly gained popularity in biomedical imaging and materials science because of its ability to provide three-dimensional images at high spatial and temporal resolution even in optically scattering environments. Currently the majority of commercial and home-built devices are based on two-photon fluorescence and harmonic generation contrast. These two contrast mechanisms are relatively easy to measure but can access only a limited range of endogenous targets. Recent developments in fast laser pulse generation, pulse shaping, and detection technology have made accessible a wide range of optical contrasts that utilize multiple pulses of different colors. Molecular excitation with multiple pulses offers a large number of adjustable parameters. For example, in two-pulse pump-probe microscopy, one can vary the wavelength of each excitation pulse, the detection wavelength, the timing between the excitation pulses, and the detection gating window after excitation. Such a large parameter space can provide much greater molecular specificity than existing single-color techniques and allow for structural and functional imaging without the need for exogenous dyes and labels, which might interfere with the system under study. In this review, we provide a tutorial overview, covering principles of pump-probe microscopy and experimental setup, challenges associated with signal detection and data processing, and an overview of applications.

The pathology of melanoma

Although melanoma represents only 10% of all skin cancer diagnoses, it accounts for at least 65% of all skin cancer-related deaths. The number of new cutaneous melanoma cases projected during 2010 was 68,000-a 23% increase from the 2004 prediction of 55,100 cases. In 2015, the lifetime risk of developing melanoma is estimated to increase to 1 in 50. As the incidence of melanoma continues to rise, now more than ever, clinicians and histopathologists must have familiarity with the various clinical and pathologic features of cutaneous melanoma.

A study assessing the feasibility and diagnostic accuracy of real-time teledermatopathology

Dermatopathology represents the gold standard for the diagnosis of skin diseases and neoplasms that cannot be diagnosed on clinical grounds alone. The aim of this study was to test the feasibility and to assess the accuracy of an Internet-based real-time (live) teledermatopathology consultation. Twenty teaching cases and 10 randomly selected routine cases were presented to four expert dermatopathologists, first by real-time teledermatopathology and, subsequently, in a blinded fashion, using light microscopy. Throughout the study the overall diagnostic accuracy did not differ for the two methods. However, the mean level of confidence and the mean observation times differed significantly between real-time teledermatopathology and light microscopy (92.6±0.24% versus 99.5±0.02%, and 96.31±11.55 sec versus 25.47±3.85 sec, respectively). Assessment of routine cases did not produce significant diagnostic differences between the two methods. These results prove that real-time teledermatopathology offers an affordable and technically simple technology that lends itself to training as well as to diagnosis of lesions from routine practice by experts situated at remote sites.

Histopathological diagnostics of malignant melanoma in accordance with the recent AJCC classification 2009: Review of the literature and recommendations for general practice

BACKGROUND

TNM classifications are the basis for diagnostic and therapeutic procedures in oncology. Histopathological reports have to enable a proper indexing of tumor specific findings into recent classifications.

METHODS

A systematic review of the literature was performed to identify reports dealing with the assessment of mitotic rate and the processing and evaluation of sentinel node biopsies in malignant melanoma. On the basis of this review an expert panel of dermatopathologists and general pathologists discussed and agreed recommendations for general practice.

RESULTS

Following recommendations were agreed with a broad consensus (93-100 % agreement): The determination of the mitotic rate in primary melanoma is performed on HE slides. The evaluation of an area of 1 mm(2) is sufficient. Only dermal mitoses are considered. The counted number of mitoses is provided as an integer value. The mitotic rate shall be determined in primary melanomas of ≤1.00 mm vertical tumor thickness according to the hot-spot method and provided as an integer value in relation to an area of 1 mm(2) . The determination of the mitotic rate in the case of thicker primary melanomas is desirable. In general, for the evaluation of each sentinel lymph node, 4 slides should be prepared. For diagnostic purposes, immunohistochemistry (preferably with antibodies against S100ß, Melan A and HMB-45) should be performed in addition to HE staining. The pathology report should provide information about micro-metastases and their longest extension (one-tenth of a millimeter).

CONCLUSIONS

These recommendations are suitable for standardizing the histopathological diagnosis of malignant melanoma and for providing a common basis for clinical decisions and scientific research.

A label-free indicator for tumor cells based on the CH2-stretch ratio

In this paper, we assess the potential of a label-free infrared absorbance based measurement method for determination of the CH(2)-symmetric to CH(2)-antisymmetric stretch ratio, to aid in the detection of the presence of cancer cells and to differentiate between various cancer cells. For this study a normal epithelial kidney cell line, two carcinoma epithelial kidney cell lines, an adult primary human melanocyte cell line, and three human melanoma cell lines were investigated. For the measurements we used a self-designed IR sensor which has the potential to be further developed in a point-of-care instrument. To investigate the mechanism influencing the CH(2)-stretch ratio of mammalian cell membranes, a normal epithelial kidney cell line was exposed to the plasma membrane bound cholesterol reducing agent methyl-β-cyclodextrin. This methodology yielded statistically significant CH(2)-stretch ratio differences between the individual cell lines, normal and tumorous, of both epithelial kidney and melanocyte origin. Measurement results of normal epithelial kidney cells exposed to methyl-β-cyclodextrin indicate that an increase in the CH(2)-stretch ratio arises when there is a decrease in, or redistribution of, the membrane stabilizing agent cholesterol. This study proves that the proposed cell type discrimination method, based on the CH(2)-symmetric to CH(2)-antisymmetric stretch ratio, allows the discrimination between normal and tumor cells. In addition, the method shows high potential for improvement of staging of suspicious tissues.

Comparative diagnostic accuracy in virtual dermatopathology

BACKGROUND

Virtual microscopy can be used to teach histology and pathology and for in-training and certification examinations. A few online consultation websites already utilize virtual microscopy, thereby expanding the role of telemedicine in dermatopathology. There are, however, relatively few studies comparing the diagnostic accuracy and acceptability of virtual slides compared to traditional glass slides.

METHODS

Ten Nordic dermatopathologists and pathologists were given a randomized combination of 20 virtual and glass slides and asked to identify the diagnoses. They were then asked to give their impressions about the virtual images. Descriptive data analysis and comparison of groups using Fisher's exact test were performed.

OBJECTIVE

To compare the diagnostic ability of dermatopathologists and pathologists in two image formats: the traditional (glass) microscopic slides, and whole mount digitized images, and to elucidate their assessment of virtual microscopy in dermatopathology.

RESULTS

Dermatopathologists and pathologists performed similarly in diagnosing dermatopathological disorders using virtual slides vs. glass slides, virtual 0.85 and glass 0.81, P=0.286. The order of administration of virtual or glass slides did not affect the percentage of questions answered correctly. Seven of nine participants completing the questionnaire, felt virtual microscopy is useful for both learning and testing.

CONCLUSION

There was no significant difference in the participants' diagnostic ability using virtual slides compared with glass slides. Most participants agreed that virtual microscopy is a useful tool for learning and testing.

Histopathological characterization of primary cutaneous melanoma using infrared microimaging: a proof-of-concept study

BACKGROUND

The diagnosis of malignant melanoma is based upon the histological evaluation of the lesion. As such, the morphological interpretation relies on the expertise of a dermatopathologist. Infrared microimaging is emerging as a new powerful tool to investigate tissue biochemistry. Infrared spectra probe the biochemical constitution of the sample and are real tissue-specific spectroscopic fingerprints.

OBJECTIVES

To assess the potential of infrared microimaging to aid in the analysis of tissue sections from primary cutaneous melanomas.

METHODS

Ten samples of melanoma sections from the main histological subtypes were investigated using infrared microimaging combined with multivariate statistical analyses.

RESULTS

This methodology yielded highly contrasted colour-coded images that permitted to highlight tissue architecture without any staining. It was possible to discriminate tumour areas from normal epidermis automatically, and intratumoral heterogeneity as revealed by our approach was correlated with the aggressiveness of the tumour.

CONCLUSIONS

This proof-of-concept study shows that infrared microimaging could help in the diagnosis of primary cutaneous melanoma.

Pigmented lesion pathology: what you should expect from your pathologist, and what your pathologist should expect from you

The first part of this review examines the reliability of histologic diagnosis in pigmented lesions, as measured by concordance studies and medicolegal analysis. It emphasizes the role of clinicians in maximizing that reliability, by providing adequate clinical descriptions, using appropriate biopsy technique, and critically interpreting pathology reports. It identifies those entities that are especially problematic, either because they cannot be reliably recognized by the histopathologist or because their histology is a poor guide to their biologic behavior. The second part of the review is a guide to some of the more difficult and controversial pigmented lesions, including dysplastic nevus, spitzoid nevi and melanomas, cellular blue nevus, animal-type melanoma, and deep penetrating nevus.

Cytopathologic diagnoses of fine-needle aspirations from endoscopic ultrasound of the mediastinum

BACKGROUND

Endoscopic ultrasound-guided fine-needle aspiration biopsy through the esophagus (EUS-FNA) or the bronchial tree (endobronchial ultrasound guided transbronchial needle aspiration [EBUS-TBNA]) may be used to obtain specimens from mediastinal structures. The accuracy of this procedure has been well documented. However, no studies have studied the reproducibility of the pathologic assessment of the aspirated material.

METHODS

A total of 102 slides from EUS-FNA or EBUS-TBNA were assessed 2 times by 4 pathologists who classified each slide to 1 of 5 diagnostic categories and judged if the aspirate came from a lymph node. Between the 2 rounds the criteria to be used in the assessment of the slides were reviewed in a limited education session. The 4 observers had at least 15 years of pathology experience, but their experience in EUS-FNA and/or EBUS-TBNA varied from almost none to more than 10 years. The kappa statistic was applied for the analysis of reproducibility.

RESULTS

The reproducibility of the diagnoses in the first round was good to excellent (kappa, 0.52-0.89). The teaching session led to a significant improvement of the reproducibility between the least and the most experienced observers (kappa ranges of 0.52-0.55 in the first round improved to 0.65-0.71 in the second round).

CONCLUSIONS

The reproducibility of the diagnosis on EBUS-TBNA and EUS-FNA is excellent among pathologists experienced with these types of samples. Pathologists who are generally experienced but have little experience with EBUS-TBNA and EUS-FNA show a steep learning curve. From a pathologic point of view, EBUS-TBNA and EUS-FNA are feasible, but only experienced pathologists should do the assessments.