Observer variation in the measurement of Breslow depth and Clark's level in thin cutaneous malignant melanoma

Histological interpretation of spitzoid tumours: an extensive machine learning-based concordance analysis for improving decision making

The histopathological classification of melanocytic tumours with spitzoid features remains a challenging task. We confront the complexities involved in the histological classification of these tumours by proposing machine learning (ML) algorithms that objectively categorise the most relevant features in order of importance. The data set comprises 122 tumours (39 benign, 44 atypical and 39 malignant) from four different countries. BRAF and NRAS mutation status was evaluated in 51. Analysis of variance score was performed to rank 22 clinicopathological variables. The Gaussian naive Bayes algorithm achieved in distinguishing Spitz naevus from malignant spitzoid tumours with an accuracy of 0.95 and kappa score of 0.87, utilising the 12 most important variables. For benign versus non-benign Spitz tumours, the test reached a kappa score of 0.88 using the 13 highest-scored features. Furthermore, for the atypical Spitz tumours (AST) versus Spitz melanoma comparison, the logistic regression algorithm achieved a kappa value of 0.66 and an accuracy rate of 0.85. When the three categories were compared most AST were classified as melanoma, because of the similarities on histological features between the two groups. Our results show promise in supporting the histological classification of these tumours in clinical practice, and provide valuable insight into the use of ML to improve the accuracy and objectivity of this process while minimising interobserver variability. These proposed algorithms represent a potential solution to the lack of a clear threshold for the Spitz/spitzoid tumour classification, and its high accuracy supports its usefulness as a helpful tool to improve diagnostic decision-making.

Skin Melanoma Detection in Microscopic Images Using HMM-Based Asymmetric Analysis and Expectation Maximization

Melanoma is one of the deadliest types of skin cancer with increasing incidence. The most definitive diagnosis method is the histopathological examination of the tissue sample. In this paper, a melanoma detection algorithm is proposed based on decision-level fusion and a Hidden Markov Model (HMM), whose parameters are optimized using Expectation Maximization (EM) and asymmetric analysis. The texture heterogeneity of the samples is determined using asymmetric analysis. A fusion-based HMM classifier trained using EM is introduced. For this purpose, a novel texture feature is extracted based on two local binary patterns, namely local difference pattern (LDP) and statistical histogram features of the microscopic image. Extensive experiments demonstrate that the proposed melanoma detection algorithm yields a total error of less than 0.04%.

Histopathologic synoptic reporting of invasive melanoma: How reliable are the data?

BACKGROUND

Synoptic reporting is recommended by many guideline committees to encourage the thorough histologic documentation necessary for optimal management of patients with melanoma.

METHODS

One hundred fifty-one pathologists from 40 US states interpreted 41 invasive melanoma cases. For each synoptic reporting factor, the authors identified cases with "complete agreement" (all participants recorded the same value) versus any disagreement. Pairwise agreement was calculated for each case as the proportion of pairs of responses that agreed, where paired responses were generated by the comparison of each reviewer's response with all others.

RESULTS

There was complete agreement among all reviewers for 22 of the 41 cases (54%) on Breslow thickness dichotomized at 0.8 mm, with pairwise agreement ranging from 49% to 100% across the 41 cases. There was complete agreement for "no ulceration" in 24 of the 41 cases (59%), with pairwise agreement ranging from 42% to 100%. Tumor transected at base had complete agreement for 26 of the 41 cases (63%), with pairwise agreement ranging from 31% to 100%. Mitotic rate, categorized as 0/mm² , 1/mm² , or 2/mm² , had complete agreement for 17 of the 41 cases (41%), with pairwise agreement ranging from 36% to 100%. Regression saw complete agreement for 14 of 41 cases (34%), with pairwise agreement ranging from 40% to 100%. Lymphovascular invasion, perineural invasion, and microscopic satellites were rarely reported as present. Respectively, these prognostic factors had complete agreement for 32 (78%), 37 (90%), and 18 (44%) of the 41 cases, and the ranges of pairwise agreement were 47% to 100%, 70% to 100%, and 53% to 100%, respectively.

CONCLUSIONS

These findings alert pathologists and clinicians to the problem of interobserver variability in recording critical prognostic factors.

LAY SUMMARY

This study addresses variability in the assessment and reporting of critical characteristics of invasive melanomas that are used by clinicians to guide patient care. The authors characterize the diagnostic variability among pathologists and their reporting methods in light of recently updated national guidelines. Results demonstrate considerable variability in the diagnostic reporting of melanoma with regard to the following: Breslow thickness, mitotic rate, ulceration, regression, and microscopic satellites. This work serves to alert pathologists and clinicians to the existence of variability in reporting these prognostic factors.

Five-year survival in patients with nodular and superficial spreading melanomas in the US population

BACKGROUND

Although superficial spreading melanomas (SSM) are diagnosed as thinner lesions, nodular melanomas (NM) have a more rapid growth rate and are biologically more aggressive compared with other histologic subtypes.

OBJECTIVE

To determine the difference in 5-year relative survival in patients with NM and SSM at the same Breslow depth and TNM stage.

METHODS

A population-based cross-sectional analysis compared the 5-year relative survival of patients with NM and SSM using data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER)∗Stat software (version 8.2.1-8.3.5). Chi-square tests compared the proportions, and Kaplan-Meier method with Z-score compared 5-year relative survival.

RESULTS

For patients receiving a diagnosis between 2004 and 2009, 5-year relative survival was lower in NM compared with SSM (53.7% vs 87.3%; Z score, -41.35; P < .001). Similarly, for patients receiving a diagnosis between 2010 and 2015, 5-year relative survival was lower in NM compared with SSM (61.5% vs 89.7%; Z score, -2.7078; P < .01). Subgroup analyses showed inferior survival in NM in T1b, and survival differences remained significant after excluding patients with nodal or distant metastases.

CONCLUSIONS

Five-year relative survival is worse in NM compared with SSM especially in T1b, T2a, and T2b melanomas. Melanoma subtype should be taken into consideration when making treatment recommendations.

Discordance in Diagnosis of Melanocytic Lesions and Its Impact on Clinical Management

CONTEXT.—

Accurate diagnosis of melanocytic lesions is fundamental for appropriate clinical management.

OBJECTIVE.—

To evaluate the degree of discordance, if any, between histopathologic diagnoses of melanocytic lesions at referring institutions and at a tertiary referral cancer center and the potential impact of such discordance on clinical management.

DESIGN.—

We retrospectively identified all patients referred to our comprehensive cancer center for evaluation of a melanocytic lesion from January 2010 to January 2011. For each patient, the histopathologic diagnosis from the referring institution was compared with the histopathologic diagnosis from a dermatopathologist at our center. Discordances were classified as major if they resulted in a change in clinical management and minor if they did not.

RESULTS.—

A total of 1521 cases were included. The concordance rates were 72.2% (52 of 72) for dysplastic nevus, 75.0% (15 of 20) for all other types of nevi, 91.1% (143 of 157) for melanoma in situ, 96.1% (758 of 789) for invasive melanoma, and 99.6% (478 of 480) for metastatic melanoma. Major discordances were found in 20.2% of cases (307 of 1521), and minor discordances were found in 48.8% of cases (742 of 1521). Compared with the guideline-based treatment recommendation based on the referring-institution diagnosis, the guideline-based treatment recommendation based on the cancer center diagnosis was more extensive in 5.9% (89 of 1521) of patients and less extensive in 5.0% (76 of 1521) of patients.

CONCLUSIONS.—

Our findings underscore the importance of secondary histopathologic review of melanocytic lesions by expert dermatopathologists because significant changes in the diagnosis, tumor classification, and/or staging may be identified; thus, resulting in critical changes in recommendations for clinical management.

Incorporation of dermoscopy improves inter-observer agreement among dermatopathologists in histologic assessment of melanocytic neoplasms

Histopathologic assessment of melanocytic neoplasms is the current gold standard of diagnosis. However, there are well recognized limitations including inter-observer diagnostic discordance. This study aimed to determine if integrating dermoscopy with histopathology of melanocytic neoplasms impacts diagnosis and improves inter-observer agreement. We conducted a prospective cohort study in a pigmented lesion clinic. Consecutive melanocytic lesions were identified for biopsy based on atypical gross or dermoscopic features. Standardized immunohistochemistry and levels were ordered on each specimen. The cases were randomized. Three dermatopathologists blinded to the clinical impression assessed each lesion. The cases were then re-randomized and re-assessed with addition of gross clinical and dermoscopic images. Inter-rater reliability (IRR) using Fleiss' kappa statistic revealed an increase from 0.447 without to 0.496 with dermoscopy amongst all dermatopathologists. The kappa increased from 0.495 before to 0.511 with dermoscopy in separating high-grade atypia or melanoma from moderate atypia or less. In 16 of 136 cases, at least 2 of 3 dermatopathologists favored a diagnosis of melanoma only after dermoscopy. In total, the consensus grade of atypia changed in 24.3% (33/ 136) of cases thereby representing changes to excisional margins and patient follow up. This study is limited by the cohort size. Dermoscopy significantly impacts diagnosis and improves identification of early melanomas in high risk populations and improves inter-observer agreement.

Pathologists' agreement on treatment suggestions for melanocytic skin lesions

BACKGROUND

Although treatment guidelines exist for melanoma in situ and invasive melanoma, guidelines for other melanocytic skin lesions do not exist.

OBJECTIVE

To examine pathologists' treatment suggestions for a broad spectrum of melanocytic skin lesions and compare them with existing guidelines.

METHODS

Pathologists (N = 187) completed a survey and then provided diagnoses and treatment suggestions for 240 melanocytic skin lesions. Physician characteristics associated with treatment suggestions were evaluated with multivariable modeling.

RESULTS

Treatment suggestions were concordant with National Comprehensive Cancer Network guidelines for the majority of cases interpreted as melanoma in situ (73%) and invasive melanoma (86%). Greater variability of treatment suggestions was seen for other lesion types without existing treatment guidelines. Characteristics associated with provision of treatment suggestions discordant with National Comprehensive Cancer Network guidelines were low caseloads (invasive melanoma), lack of fellowship training or board certification (melanoma in situ), and more than 10 years of experience (invasive melanoma and melanoma in situ).

LIMITATIONS

Pathologists could not perform immunohistochemical staining or other diagnostic tests; only 1 glass side was provided per biopsy case.

CONCLUSIONS

Pathologists' treatment suggestions vary significantly for melanocytic lesions, with lower variability for lesion types with national guidelines. Results suggest the need for standardization of treatment guidelines for all melanocytic lesion types.

Current state of melanoma diagnosis and treatment

Melanoma is the deadliest form of skin cancer. In the early stages, melanoma can be treated successfully with surgery alone and survival rates are high, but after metastasis survival rates drop significantly. Therefore, early and correct diagnosis is key for ensuring patients have the best possible prognosis. Melanoma misdiagnosis accounts for more pathology and dermatology malpractice claims than any cancer other than breast cancer, as an early misdiagnosis can significantly reduce a patient’s chances of survival. As far as treatment for metastatic melanoma goes, there have been several new drugs developed over the last 10 years that have greatly improved the prognosis of patients with metastatic melanoma, however, a majority of patients do not show a lasting response to these treatments. Thus, new biomarkers and drug targets are needed to improve the accuracy of melanoma diagnosis and treatment. This article will discuss the major advancements of melanoma diagnosis and treatment from antiquity to the present day.

Pathological review of primary cutaneous malignant melanoma by a specialist skin cancer multidisciplinary team improves patient care in the UK

AIMS

The National Institute for Health and Care Excellence advocated the development of specialist skin cancer multidisciplinary teams (SSMDTs) for the management of higher risk invasive skin cancers in the UK. The interobserver variability in the histopathological assessment of primary cutaneous malignant melanoma (PCMM) is well recognised.

METHODS

We evaluated the discordance rates in the assessment of the histopathological criteria of PCMM based on the eighth American Joint Committee on Cancer (AJCC) melanoma staging system and subsequent change in prognosis and management following pathology review by an SSMDT.

RESULTS

353 cases of PCMM were referred to our SSMDT between April 2015 and May 2016. Cases in which there was a discrepancy in one or more histological parameters following expert review were collected retrospectively. Of 341 eligible cases, there were 94 (27.6%) in which there was an alteration in any parameter. There was interobserver agreement in final diagnosis in 96.8%, Breslow thickness in 86.8%, ulceration in 98.2%, microsatellites in 98.5%, tumour mitotic rate in 88.9%, histological subtype in 92.4%, growth phase in 98.5%, angiolymphatic invasion in 97.7%, perineural invasion in 98.8%, regression in 95.3% and tumour-infiltrating lymphocytes in 95.0%. A corresponding change in AJCC stage occurred in 23 cases (6.7%), with a resulting change in clinical management in 10 cases (2.9%).

CONCLUSIONS

Disagreements in the pathological assessment of PCMM can have significant clinical implications for a small number of patients. Our findings highlight the value of the SSMDT for high-quality care of patients with melanoma in the UK.

Inter-observer variation in the histopathology reports of head and neck melanoma; a comparison between the seventh and eighth edition of the AJCC staging system

BACKGROUND

TNM staging of melanoma has recently been altered by the introduction of the 8th edition of the AJCC Cancer Staging manual. The purpose of this study is to analyze the inter-observer variation of histopathology reports and its effect on recommended treatment policy.

METHODS

We retrospectively analyzed 296 cases, diagnosed as primary cutaneous head and neck melanoma (2005-2016), referred to the Netherlands Cancer Institute (NCI) for treatment after prior diagnosis in another hospital (non-NCI). All reports were analyzed for patients demographics, tumor characteristics and histopathologic features.

RESULTS

In 53% and 40% of the cases, the histopathologic parameters were discordant, according to AJCC 7th and 8th edition, respectively. This indicated a perfect inter-observer agreement for the measurement of Breslow thickness (Intraclass correlation coefficient (ICC) = 0.981) and a substantial agreement for subtype (kappa statistic (κ) = 0.648) and ulceration (κ = 0.802), while only moderate for dermal mitotic activity (κ = 0.472). After NCI review, recommended treatment policies were changed in 13% and 11% of the patients when applying TNM 7 and TNM 8, respectively. Scheduling sentinel lymph node biopsy (SLNB) changed in 14 (5%) and 10 (3%) cases when using TNM 7 and TNM 8, respectively.

CONCLUSION

Review by a NCI pathologist of histopathologic parameters of primary cutaneous head and neck melanoma led to significant changes in treatment decision. Introduction of the AJCC 8th edition led to slightly less discordances between NCI and non-NCI reports and consequently smaller impact on treatment planning. Expert review remains indicated when a SLNB is considered for additional staging in selected cases.

Concordance and Reproducibility of Melanoma Staging According to the 7th vs 8th Edition of the AJCC Cancer Staging Manual

IMPORTANCE

The recently updated American Joint Committee on Cancer (AJCC) classification of cancer staging, the AJCC Cancer Staging Manual, 8th edition (AJCC 8), includes revisions to definitions of T1a vs T1b or greater. The Melanoma Pathology Study database affords a comparison,of pathologists' concordance and reproducibility in the microstaging of melanoma according to both the existing 7th edition (AJCC 7) and the new AJCC 8.

OBJECTIVE

To compare AJCC 7 and AJCC 8 to examine whether changes to the definitions of T1a and T1b or greater are associated with changes in concordance and reproducibility.

DESIGN SETTING AND PARTICIPANTS

In this diagnostic study conducted as part of the national Melanoma Pathology Study across US states, 187 pathologists interpreting melanocytic skin lesions in practice completed 4342 independent case interpretations of 116 invasive melanoma cases. A consensus reference diagnosis and participating pathologists' interpretations were classified into the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis class IV (T1a) or class V ( T1b) using both the AJCC 7 and AJCC 8 criteria.

MAIN OUTCOMES AND MEASURES

Concordance with consensus reference diagnosis, interobserver reproducibility, and intraobserver reproducibility.

RESULTS

For T1a diagnoses, participating pathologists' concordance with the consensus reference diagnosis increased from 44% (95% CI, 41%-48%) to 54% (95% CI, 51%-57%) using AJCC 7 and AJCC 8 criteria, respectively. The concordance for cases of T1b or greater increased from 72% (95% CI, 69%-75%) to 78% (95% CI, 75%-80%). Intraobserver reproducibility of diagnoses also improved, increasing from 59% (95% CI, 56%-63%) to 64% (95% CI, 62%-67%) for T1a invasive melanoma, and from 74% (95% CI, 71%-76%) to 77% (95% CI, 74%-79%) for T1b or greater invasive melanoma cases.

CONCLUSIONS AND RELEVANCE

Melanoma staging in AJCC 8 shows greater reproducibility and higher concordance with a reference standard. Improved classification of invasive melanoma can be expected after implementation of AJCC 8, suggesting a positive impact on patients. However, despite improvement, concordance and reproducibility remain low.

Pathologists' diagnosis of invasive melanoma and melanocytic proliferations: observer accuracy and reproducibility study

Objective To quantify the accuracy and reproducibility of pathologists' diagnoses of melanocytic skin lesions.Design Observer accuracy and reproducibility study.Setting 10 US states.Participants Skin biopsy cases (n=240), grouped into sets of 36 or 48. Pathologists from 10 US states were randomized to independently interpret the same set on two occasions (phases 1 and 2), at least eight months apart.Main outcome measures Pathologists' interpretations were condensed into five classes: I (eg, nevus or mild atypia); II (eg, moderate atypia); III (eg, severe atypia or melanoma in situ); IV (eg, pathologic stage T1a (pT1a) early invasive melanoma); and V (eg, ≥pT1b invasive melanoma). Reproducibility was assessed by intraobserver and interobserver concordance rates, and accuracy by concordance with three reference diagnoses.Results In phase 1, 187 pathologists completed 8976 independent case interpretations resulting in an average of 10 (SD 4) different diagnostic terms applied to each case. Among pathologists interpreting the same cases in both phases, when pathologists diagnosed a case as class I or class V during phase 1, they gave the same diagnosis in phase 2 for the majority of cases (class I 76.7%; class V 82.6%). However, the intraobserver reproducibility was lower for cases interpreted as class II (35.2%), class III (59.5%), and class IV (63.2%). Average interobserver concordance rates were lower, but with similar trends. Accuracy using a consensus diagnosis of experienced pathologists as reference varied by class: I, 92% (95% confidence interval 90% to 94%); II, 25% (22% to 28%); III, 40% (37% to 44%); IV, 43% (39% to 46%); and V, 72% (69% to 75%). It is estimated that at a population level, 82.8% (81.0% to 84.5%) of melanocytic skin biopsy diagnoses would have their diagnosis verified if reviewed by a consensus reference panel of experienced pathologists, with 8.0% (6.2% to 9.9%) of cases overinterpreted by the initial pathologist and 9.2% (8.8% to 9.6%) underinterpreted.Conclusion Diagnoses spanning moderately dysplastic nevi to early stage invasive melanoma were neither reproducible nor accurate in this large study of pathologists in the USA. Efforts to improve clinical practice should include using a standardized classification system, acknowledging uncertainty in pathology reports, and developing tools such as molecular markers to support pathologists' visual assessments.

Breslow Thickness Measurements of Melanomas Around American Joint Committee on Cancer Staging Cut-Off Points: Imprecision and Terminal Digit Bias Have Important Implications for Staging and Patient Management

BACKGROUND

Breslow thickness is the most important prognostic factor in patients with clinically localized primary cutaneous melanomas, and its accuracy has important implications for staging and management. A review of the Melanoma Institute Australia database and population-based data for the state of New South Wales, Australia, found an unexpectedly large number of melanomas reported as being exactly 1.0 mm thick. We sought to determine possible causes for this biologically implausible finding.

METHODS

The tumor thickness of 125 invasive cutaneous melanomas with a recorded Breslow thickness of 0.9-1.1 mm was remeasured and recorded by two pathologists.

RESULTS

Concordance of measurements between the two pathologists was high (intraclass correlation coefficient 0.816, 95 % CI 0.733-0.873). The original measurements showed clustering at 0.9, 1.0, and 1.1 mm, whereas the review measurements did not. The original measurements staged 84 cases (72 %) as T1 and 33 (28 %) as T2, while the reviewed measurements staged 58 cases (50 %) as T1 and 59 (50 %) as T2 (p < 0.001).

CONCLUSIONS

Our study demonstrated imprecision in Breslow thickness measurements and its significant impact on staging. Two potential sources of imprecision are failure to follow standardized thickness measurement guidelines and the phenomenon of terminal digit bias, not previously identified as a problem in this field. Educating pathologists about this phenomenon and the importance of utilizing ocular micrometers may improve the precision of melanoma thickness measurements around critical staging cut-off points. Clinicians must also be educated to appreciate that there is an inevitable margin of error with Breslow thickness measurements that should be considered when making management decisions.

Discordance of histopathologic parameters in cutaneous melanoma: Clinical implications

BACKGROUND

Histopathologic analysis remains the gold standard for the diagnosis of melanoma, however previous studies have shown a substantial rate of interobserver variability in the evaluation of melanocytic lesions.

OBJECTIVE

We sought to evaluate discordance in the histopathological diagnosis and microstaging parameters of melanoma and subsequent impact on clinical management.

METHODS

This was a retrospective review of 588 cases of cutaneous melanoma and melanoma in situ from January 2009 to December 2014 that were referred to Emory University Hospital, Atlanta, GA, for treatment. Per institutional policy, all outside melanoma biopsy specimens were reviewed internally. Outside and institutional reports were compared.

RESULTS

Disagreement between outside and internal reports resulted in a change in American Joint Committee on Cancer pathologic stage in 114/588 (19%) cases, resulting in a change in management based on National Comprehensive Cancer Network guidelines in 105/588 (18%) cases.

LIMITATIONS

Given the retrospective nature of data collection and the bias of a tertiary care referral center, cases in this study may not be representative of all melanoma diagnoses.

CONCLUSION

These findings confirm consistent subjectivity in the histopathologic interpretation of melanoma. This study emphasizes that a review of the primary biopsy specimen may lead to significant changes in tumor classification, resulting in meaningful changes in clinical management.

Reproducibility of AJCC staging parameters in primary cutaneous melanoma: an analysis of 4,924 cases

BACKGROUND

Pathology reports are of critical importance for conveying information to clinicians who must make important management decisions for their patients. This study sought to assess and compare the precision, reproducibility, and completeness of external pathology reports and pathology reports generated by central review of each case in a large cohort of primary cutaneous melanoma patients.

METHODS

Details of matched external pathology reports and corresponding review reports for 4,924 primary cutaneous invasive melanomas diagnosed and treated at Melanoma Institute Australia (MIA) between 2001 and 2011 were analyzed.

RESULTS

Interobserver agreement was excellent for American Joint Committee on Cancer (AJCC) T staging parameters: Breslow thickness (intraclass correlation coefficient [ICC] 0.984), mitotic rate (ICC 0.833), and ulceration (kappa statistic [κ] 0.823). All three of these important pathologic variables were included in 92.4 and 66.9% of review (MIA) and external (non-MIA) pathology reports, respectively. Completeness of MIA and non-MIA pathology reports for the three essential T-staging criteria increased significantly from 87.9 to 94.6% (χ(2) = 9.1, df = 1, P = 0.003) and from 53.2 to 74.3% (χ(2) = 35.0, df = 1, P < 0.001) over the 10-year study period. The AJCC N staging parameter of microsatellites was recorded in only 43% of non-MIA reports and demonstrated moderate concordance (κ = 0.560).

CONCLUSIONS

Reproducibility and completeness of pathology reports for many important histopathologic features have improved in recent years. Nevertheless, the documentation of microsatellites remained poor in external pathology reports. To enhance the usefulness of the pathology report for the provision of optimal melanoma patient care, continued efforts to encourage pathologists to document its key features appear warranted.

The MPATH-Dx reporting schema for melanocytic proliferations and melanoma

BACKGROUND

The histologic diagnosis of melanoma and nevi can be subject to discordance and errors, potentially leading to inappropriate treatment and harm. Diagnostic terminology is not standardized, creating confusion for providers and patients and challenges for investigators.

OBJECTIVE

We sought to describe the development of a pathology reporting form for more precise research on melanoma and a diagnostic-treatment mapping tool for improved patient care and consistency in treatment.

METHODS

Three dermatopathologists independently reviewed melanocytic lesions randomly selected from a dermatopathology database. Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-Dx) reporting schema evolved from iterative case review and form revision.

RESULTS

Differences in diagnostic thresholds, interpretation, and nomenclature contributed to development of the MPATH-Dx histology reporting form, which groups lesions by similarities in histogenesis and degrees of atypia. Because preliminary results indicate greater agreement regarding suggested treatments than for specific diagnoses, the diverse terminologies of the MPATH-Dx histology reporting form were stratified by commonalities of treatments in the MPATH-Dx diagnostic-treatment mapping scheme.

LIMITATIONS

Without transformative advances in diagnostic paradigms, the interpretation of melanocytic lesions frequently remains subjective.

CONCLUSIONS

The MPATH-Dx diagnostic-treatment mapping scheme could diminish confusion for those receiving reports by categorizing diverse nomenclature into a hierarchy stratified by suggested management interventions.

Differences in tumor thickness between hematoxylin and eosin and Melan-A immunohistochemically stained primary cutaneous melanomas

Tumor thickness (Breslow thickness) represents the main prognostic factor in primary melanoma. Potential differences in melanoma tumor thickness measurements between conventional hematoxylin and eosin (H&E) and Melan-A immunohistochemical staining were evaluated. Ninety-nine excisional biopsies were included in the study. From each sample, 2 consecutive histological sections were stained with H&E and Melan-A, respectively. Tumor thickness was measured from both sections by 2 independent observers. In 59 biopsy specimens (59.6%), higher tumor thickness measurements were recorded in Melan-A-stained than in H&E-stained sections. In 42.4% of such cases (25 biopsies), the observed differences were ≥0.2 mm. After Melan-A evaluation, 33% of in situ melanoma cases were reclassified as invasive melanoma, with thickness measurements ranging from 0.15 to 0.35 mm. In 23 biopsies, identical values were recorded with both techniques, whereas in 17 cases, measurements obtained with H&E staining were slightly higher (from 0.01 to 0.18 mm) than those obtained with Melan-A staining. A high rate of interobserver agreement was noted, and significant intertechnique measurement differences were detected. Significant discrepancies (≥0.2 mm) in thickness measurements between the 2 techniques were mainly attributed to the presence of individual or small clusters of melanocytic cells in the papillary dermis. These melanocytic cells could be easily overlooked in H&E-stained sections, especially in sections showing dense lymphohistiocytic inflammatory infiltrates, numerous melanin-containing histiocytic cells in the upper dermis, or extensive fibrotic changes or regression phenomena. This study confirms the practical interest of immunohistochemical staining with Melan-A in evaluating primary melanoma and, specifically, in situ melanoma cases.

Useof anti-phosphohistone H3 immunohistochemistry to determine mitotic rate in thin melanoma

The seventh edition of the American Joint Committee on Cancer (AJCC) melanoma staging system, slated for release in 2010, will introduce mitotic rate (MR) as one of the primary criteria for staging thin melanoma (< or = 1.0 mm). Accurate counts are essential because the finding of a single mitotic figure (MF) will alter the staging and management of these patients. The traditional manner of counting of mitotic figures (MFs) using a X40 objective is time consuming and prone to inter- and intraobserver variability. We employed an antibody to phosphohistone H3 (pHH3, ser10) that labels MFs in all stages of mitosis, to evaluate mitotic counts at X20 in tissue sections from 30 melanoma patients with thin lesions 0.45 to 1.2 mm in depth, and compared results with routine hematoxylin and eosin (H&E) in a double-blind fashion. The mean MR was 1.63 by antipHH3, and 0.67 for H&E, representing a mean increase of 243%. The Spearman correlation coefficient for MR in H&E and anti-pHH3 sections was 0.88 (P < 0.0001). When melanomas were designated as "mitotically active," if the MR by anti-pHH3 was > or = 2 and > or = 1 by H&E, the correlation coefficient increased to 1.0. No thin melanomas were mitotically inactive on anti-pHH3 but active on H&E. Results indicate that anti-pHH3 is a useful immunostain for labeling melanocytes in mitosis. Subsequent studies will be needed confirm the accuracy of this staining technique, which has the potential to be used as a screening method for counting MFs before conventional H&E methodology in the microstaging of thin melanoma.

Pathology Review of Thin Melanoma and Melanoma in Situ in a Multidisciplinary Melanoma Clinic: Impact on Treatment Decisions

Purpose

Patients with thin melanoma (≤ 1.0 mm) and melanoma in situ (MIS) represent the majority of newly diagnosed melanoma. We estimated the impact of expert review of outside pathology material on the staging and thus treatment decisions affecting patients referred to a multidisciplinary clinic with early-stage melanoma.

Patients and Methods

We studied patients with a diagnosis of thin melanoma or MIS referred to H. Lee Moffitt Cancer Center from 2006 to 2009. After comparing the referring laboratory and in-house dermatopathologic interpretations, we calculated any differences in diagnosis and tumor staging and the potential impact of differences in diagnosis and staging on prognosis and surgical treatment using the National Comprehensive Cancer Network clinical guidelines.

Results

The overall pathologic discordance rate in diagnosis was 4% (15 of 420 patients; 95% CI, 2% to 6%). The overall change in tumor staging rate was 24% (97 of 405 patients; 95% CI, 20% to 28%). Pathology review led to changes in surgical excision margins in 12% of patients (52 of 420 patients; 95% CI, 9% to 16%) and in the decision about whether to perform a sentinel lymph node biopsy in 16% of patients (67 of 420 patients; 95% CI, 13% to 20%). Key pathologic factors, particularly mitotic rate, were frequently missing from outside pathology reports.

Conclusion

Our data suggest that review of thin melanoma or MIS by an expert dermatopathologist results in frequent, clinically meaningful alterations in diagnosis, staging, prognosis, and surgical treatment. Referral of these patients to a multidisciplinary melanoma clinic is appropriate, and management of such patients should include review of the biopsy whenever feasible.

Medical malpractice and cancer of the skin

BACKGROUND

A litigation crisis exists in this country, and it may be better understood through analysis of lawsuits. Verdict summary analysis has been used for this purpose.

METHODS

Ninety-nine jury verdict reviews from 1986 to 2001 were obtained from a computerized database. Reviews compiled data on defendants, plaintiffs, allegations of wrongdoing, cancer cell types, sites, outcomes, and case summaries. Data was entered into a spreadsheet for analysis.

RESULTS

Failure to diagnose was alleged in 54%; of these, 48% alleged biopsies were inappropriately omitted. Allegations were highest for failure to diagnose in dermatologists and general practice physicians, for misdiagnosis in pathologists, and for complications in surgeons. Young patients and those with poor outcomes received more and larger awards. Trauma appears to have support for a role in causation of skin cancer in some courts.

CONCLUSIONS

The study of skin cancer suits may help develop risk management and prevention strategies.

Interobserver reproducibility of histopathologic prognostic variables in primary cutaneous melanomas

BACKGROUND

The prognosis for patients with localized primary cutaneous melanoma is known to depend principally on tumor thickness, and to a lesser extent on ulcerative state and Clark level. We have recently found in an analysis of 3661 patients that tumor mitotic rate (TMR) is also an important prognostic parameter, ranking second only to tumor thickness. However, few studies have assessed the accuracy and reproducibility with which these features of a melanoma are recorded by histopathologists.

AIM

To assess interobserver reproducibility of major pathologic prognostic parameters in cutaneous melanoma.

METHODS

Single hematoxylin and eosin-stained slides of 69 dermally invasive primary cutaneous melanomas were circulated among six pathologists with differing experience in the assessment of melanocytic tumors. The observers independently determined the tumor thickness, Clark level of invasion, ulcerative state, and TMR for each lesion. Intraclass correlation coefficients and kappa scores for multiple ratings per subject were calculated.

RESULTS

The intraclass correlation coefficients were 0.96 for tumor thickness and 0.76 for TMR. The kappa scores were 0.83 for ulcerative state and 0.60 for Clark level. These results indicated excellent agreement among the pathologists for measurements of tumor thickness, ulcerative state, and TMR and fair to good agreement for Clark level.

CONCLUSIONS

Appropriately trained and experienced histopathologists can assess prognostically important features of melanomas accurately and reproducibly. Given our recent finding of the significance of TMR in determining prognosis, it is important that this feature be assessed by a standardized method and documented for all primary cutaneous melanomas.

Prognostic factors

The American Joint Committee on Cancer has recently revised the staging system for melanoma. In this article, prognostic factors for melanoma are discussed in order of significance as outlined by the new staging system. In addition, other historically relevant prognostic factors are reviewed. The article concludes with a discussion of new technology, which may aid in the future staging of melanoma patients.

Inter-observer variation in the histopathological diagnosis of clinically suspicious pigmented skin lesions

When a biopsy is taken of a suspicious pigmented skin lesion, histological examination is expected to establish the definitive diagnosis. This study evaluated the inter-observer variation of 20 pathologists in the histological diagnosis of a randomly selected set of suspicious pigmented skin lesions (PSLs), by comparing their diagnoses to a reference diagnosis. Overall sensitivity for melanoma was 87%, ranging from 55% to 100% between the observers. Sensitivity was significantly lower for thin (Breslow thickness <1 mm) than for thick melanomas (83% versus 97%, p=0.005). Overall melanoma specificity was 94%, ranging from 83% to 100% between observers. Dysplastic naevus was the most important source of false-positive diagnoses, mainly in situ melanomas. Positive and negative predictive values in the given test set were 75% and 97%, respectively. In the case of melanoma, there was quite some variation in measured Breslow thickness. This would have led to a different therapeutic approach in 12% of the readings. Some of the variation seemed to be due to a different interpretation of the presence of a co-existent naevus. In 9% (3/35) of the readings, participants did not agree on the presence of ulceration. These results reflect a tendency to overdiagnose mainly thin melanomas in general histopathological practice. They also demonstrate variation in the assessment of major prognostic factors of melanoma.

Cytomorphometric parameters and the metastatic potential of cutaneous and uveal melanoma: a comparison with prognostic factors

The Mean of the Ten Largest Nuclei (MTLN1) is one of the most important prognostic factors in uveal malignant melanoma. This study was performed to investigate the applicability of nuclear and nucleolar measurements as a prognostic factor for cutaneous melanoma. A routine light microscope (Carl Zeiss: Axiophot EL-Einnsatz; #451888) at 640 times magnification with a Micrometer Eye Piece (Carl Zeiss: #444034) was used to evaluate the correlation of MTLN1 and Mean of Ten Largest Nuclei (MTLN) with the occurrence of metastasis in 58 primary cutaneous melanoma. For uveal melanoma, cytologic classification was used for comparison. Prognostic value was determined by univariate and multivariate linear regression analysis. MTLN1 was the only significant factor for uveal melanoma (p = 0.05). For cutaneous melanoma, all factors were significantly associated with disease progression. MTLN1 was the only one to remain significant (p + 0.027) in multivariate linear regression analysis. Nuclear and nucleolar morphometry are significant prognostic factors for uveal and cutaneous melanoma.

The velocity of ultrasound in human primary melanoma tissue - implications for the clinical use of high resolution sonography

BACKGROUND

Ultrasonography with 20 MHz frequency can be used to estimate tumour thickness preoperatively in malignant melanoma (MM) of the skin. The vertical invasion depth is the single most important prognostic factor for localised MM, and its preoperative knowledge would be very useful for the planning of surgical procedures. Since ultrasonographic distance measurements directly depend upon the tissue specific ultrasound velocity, we determined the ultrasound velocity in primary melanoma.

RESULTS

Ultrasound velocity was calculated from runtime differences of a 20 MHz ultrasound signal along a known distance either through water alone or through thick specimens of primary MM. The ultrasound velocities varied between 1553 m/s and 1588 m/s with a mean of 1564 m/s in four different MM specimens. The analysis of different parts of the specimens showed that the variation of the calculated velocities was larger between different specimens than within one individual specimen.

CONCLUSIONS

The ultrasound velocity in MM tissue may be slightly lower than normally assumed, thereby explaining a part of the overestimation usually found in sonographic measurement of melanoma invasion depth. Additionally, the variation of ultrasound velocity between individual tumours may contribute to the impairment of the correlation found between sonometry and Breslow's measurement of MM invasion depth. For practical reasons, a setting of 1580 m/s will be appropriate for ultrasonography of primary malignant melanoma.

Clinical and histologic features of level 2 cutaneous malignant melanoma associated with metastasis

BACKGROUND

Metastatic melanoma developing in patients with a level 2 primary cutaneous malignant melanoma (CMM) is rare but has been reported in studies with follow-up periods ranging up to 15 years. The objective of this study was to investigate level 2 CMM associated with metastasis in a population-based retrospective study.

METHODS

In this retrospective population-based study, all level 2 CMMs associated with metastases were identified in Western Australia during 1982-1989 and were followed up to the end of 1996.

RESULTS

Pathology reports of 2834 patients were examined. Of these, 1716 had a CMM of maximum tumor thickness 1 mm or less recorded on the pathology report. Of these, 67 had a metastatic melanoma reported on follow-up. Histologic review of these 67 cases under blind conditions identified 5 cases with a level 2 primary CMM followed by metastasis without another primary CMM. All these level 2 CMM showed established regression. Eight other patients were identified with a level 2 CMM, metastatic melanoma, and another primary CMM of at least level 3 invasion. These subsequent primaries occurred before the metastasis had been reported.

CONCLUSIONS

These findings suggest that metastasis from level 2 CMM without regression is very rare, if it occurs at all.

Accuracy of frozen section measurements for the determination of Breslow tumour thickness in primary malignant melanoma

AIMS

Microstaging of primary malignant melanoma (MM) and the width of surgical margins depend mainly on Breslow tumour thickness (BTT). The use of frozen section (FS) measurements of BTT has been doubted, and previous reports have shown conflicting results regarding the comparability to paraffin sections (PS). To look for significant differences of BTT due to freezing or paraffin embedding, we evaluated a larger series of melanocytic lesions as far as possible excluding other technical influences.

METHODS AND RESULTS

Paired 'mirror sections' of 112 melanocytic lesions (33 MM and 79 melanocytic naevi) were measured according to Breslow on single corresponding PS and FS of the same tumour specimen. Comparing measurements on FS and PS, we found very small differences of BTT on average and an almost equal distribution of BTT in the two sets of values with no statistically significant difference by applying the Wilcoxon signed rank test. Concerning the clinically most important 1 mm-threshold of BTT, 110 (98.2%) of the lesions gave equal measurements in FS and PS.

CONCLUSIONS

Frozen sections can be used for accurate measurements of Breslow tumour thickness. Consequently, intraoperative frozen section diagnosis of thick melanoma immediately followed by excision with wide surgical margins is possible in experienced centres.

Thin cutaneous malignant melanomas (< or =1.5 mm): identification of risk factors indicative of progression

BACKGROUND

Although thin cutaneous melanomas generally have a favorable prognosis, in some cases they may undergo progression. The current study was undertaken to identify variables that may predict a more aggressive clinical outcome in these patients. In addition to classic clinicopathologic features, the authors tested the prognostic impact of three new morphometric quantitative parameters: 1) tumor thickness plus regression thickness (T+R), 2) percentage of skin thickness infiltrated by tumor cells (T/S ratio), and 3) percentage of skin thickness infiltrated by tumor cells and regression ([T+R]/S ratio).

METHODS

The authors retrospectively evaluated 287 patients with invasive cutaneous melanoma < or = 1.5 mm in thickness. Disease free survival rates (Kaplan-Meier method) were compared by using the log rank test. A multivariate analysis (Cox proportional hazards model) was used to determine the independent effect of each variable on progression. Progression was defined as any documented cutaneous local and/or distant metastasis.

RESULTS

Thirty-two of the 287 patients (11.1%) underwent disease progression. The overall 5-year and 10-year disease free survival rates were 89.3% and 84.6%, respectively. In the univariate analysis, the following factors were found to be significant predictors of progression: male gender (P = 0.01), acral-lentiginous histotype (P = 0.02), tumor thickness (P = 0.005), T+R (P = 0.001), T/S ratio > or = 50% (P = 0.03), (T+R)/S ratio > or = 50% (P = 0.006), vertical growth phase (P = 0.04), and absence of inflammatory response (P < 0.0001). Conversely, age, site, and Clark's level did not affect the risk of recurrences and/or metastases significantly. In the multivariate analysis, only T+R (P = 0.009) and inflammatory response (P < 0.0001) were found to be independent predictors of progression. Five-year disease free survival rates according to presence versus absence of inflammatory response were 93.4% and 63.8%, respectively (P < 0.0001).

CONCLUSIONS

In the current study, peritumoral and intratumoral inflammatory infiltrate and T+R were found to be strong independent predictors of progression in thin cutaneous melanomas.

Malignant melanoma: prognostic indicators

The incidence of cutaneous malignant melanoma in the Caucasian population has continued to increase at an alarming rate and is expected to be 1 in 75 by the year 2000. Within the medical community, these trends have prompted an interest in factors that potentially influence the biologic activity of such lesions. Several clinical and pathologic variables have been identified that affect the progression and behavior of melanoma. On the basis of multivariate analysis, the most important factors for predicting survival in patients with stage I and II melanomas are tumor thickness, presence of ulceration, and anatomic site of the primary tumor (the prognosis is poorer with head and neck lesions than with extremity lesions). For patients with stage III melanomas, all the foregoing factors plus the extent of nodal disease are of prognostic importance. For patients with stage IV melanomas, the main prognostic factors are the number of metastatic lesions and the site of metastatic involvement (visceral lesions portend a poor outcome).

A nationwide survey of observer variation in the diagnosis of thin cutaneous malignant melanoma including the MIN terminology. CRC Melanoma Pathology Panel

AIM

To investigate observer variation in the diagnosis of thin cutaneous malignant melanoma and related lesions in a nationwide sample of histopathologists in the UK.

METHODS

Out of a random sample of 195 pathologists, 148 (76%) participated in two circulations, the first with 20 slides and the second with 25 slides. The results were compared with those for the Cancer Research Campaign (CRC) Melanoma Pathology Panel, consisting of seven histopathologists and one dermatopathologist, which had developed and evaluated diagnostic criteria.

RESULTS

In the first circulation, when no standardised diagnostic criteria were used, a fair level of agreement was achieved for an overall diagnosis using the categories benign naevi with no atypia, benign naevi with atypia and melanoma (Kappa = 0.45). This was low compared with the agreement of the panel who used agreed criteria (Kappa = 0.75). Moreover, participants in the nationwide survey were more likely to diagnose melanoma and less likely to diagnose benign naevi without atypia than the panel. In the second circulation, when diagnostic criteria and diagrams were used, there was a higher level of agreement for overall diagnosis using the categories benign, melanocytic intraepidermal neoplasia (MIN) with or without microinvasion and melanoma with vertical growth phase, and was the same as that achieved by the panel using the same criteria (Kappa = 0.68).

CONCLUSIONS

As the incidence rate of thin melanomas has been increasing in the UK, it is important that standardised diagnostic criteria are used to ensure accurate reporting of incidence and correct management of patients. The use of MIN and the vertical growth phase seemed to be generally acceptable.

Discordance in the histopathologic diagnosis of melanoma and melanocytic nevi between expert pathologists

The reliability of a diagnostic test depends on the reproducibility of the result. Many clinical diagnostic tests can be quantified with established ranges and standard deviations. Other tests are more subjective, such as those that depend on analysis of a visual image with an increased possibility of variance in the result. To study this variance, the authors analyzed the performance of expert pathologists in the interpretation of cutaneous melanocytic tumors. A panel of expert pathologists was convened to review anatomic pathology specimens from melanocytic tumors. Each pathologist submitted five specimens, from which 37 were selected for review. Only one slide was used for each case. All specimens were interpreted by each pathologist without consultation with each other. In addition to standard diagnostic terms, each specimen was designated as benign, malignant, or indeterminate. Statistical analysis was used to determine the degree of concordance. The combined kappa statistic for the eight observers and three possible outcomes (benign, malignant, or indeterminate) was 0.50. A kappa statistic of this magnitude, is defined as being moderate. In 62% of the specimens, there was unanimous agreement or only one discordant designation. Thirty-eight percent had two or more discordant interpretations. No single pathologist had a disproportionate number of discordant designations. This study mimics the consultation practice of anatomic pathology and shows the variability and discordance in diagnostic language and designation of biological behavior. The results suggest the criteria for the diagnosis of melanomas and melanocytic nevi need to be refined and more consistently applied.

Thin melanomas with unusual aggressive behavior: a report on nine cases. Melanoma Group of French Federation of Cancer Centers

BACKGROUND

The major factor influencing the prognosis of cutaneous malignant melanoma (MMs) is the maximum thickness of the tumor as measured by Breslow's method. However, it has been reported that thin melanomas, which should have an excellent prognosis, may have the potential to metastasize, some with an unusually rapid course.

OBJECTIVE

Our purpose was to examine prognostic indicators in relation to unusually rapid aggressive behavior in patients with thin MMs (<0.76mm).

METHODS

We describe nine cases of thin MM (<.76mm) that exhibited a recurrence or metastasis during a follow-up period ranging from 3 to 10 years, among computerized records of 1118 MMs treated in a multicenter epidemiologic study. The data obtained from these nine cases were compared with nonrecurring thin MM (149 cases) of the same cohort.

RESULTS

The particular aggressiveness of these thin melanomas was reflected by the short disease-free interval (3 years or less) in all ine patients. The recurring thin MM more frequently involved head and neck sites, occurred in male patients, and showed Clark's level III and IV.

CONCLUSION

Our review suggests that the head and neck area is particularly involved by unusually rapidly recurring thin MM. Possible explanations are the specific problems of surgical management and the greater sun exposure of this location.

Problems with registration of cutaneous malignant melanoma in England

The aim of the study was to assess the completeness and accuracy of cancer registration for cutaneous malignant melanoma. The study was conducted in seven health districts in England and one health board in Scotland from 1987 to 1989 with a total resident population of 3.6 million. Records from pigmented lesion clinics and pathology laboratories collected during the Cancer Research Campaign's health education programme to promote the early detection of melanoma were matched with cancer registrations from a total of five regional cancer registries. In England 74% out of a total of 642 cases of invasive malignant melanomas (ICD 172) and 44% out of a total of 155 in situ melanomas (ICD 232) had been registered compared with 96% and 100% respectively in Scotland. A significantly higher proportion of late-stage cases was found among registered than among non-registered cases in England (P < 0.001). In all registries the majority of superficial spreading in situ melanomas were miscoded as invasive cases. The annual incidence of invasive malignant melanoma in the English study areas was found to be seven per 100,000 in men and 11 per 100,000 in women, similar to that reported in Scotland. The registries are best at recording thick or late-stage melanomas. As the skin cancer target for Health of the Nation depends on monitoring trends in the incidence of malignant melanoma, future improved ascertainment of cases and changes in the type of cases being registered must be taken into account.

Observer variation in histological classification of cutaneous malignant melanoma

To evaluate the variations within and between observers in the interpretation of important histological prognostic factors, a series of 96 melanoma patients was randomly selected from a database of 1691 patients with cutaneous malignant melanoma. The stained sections were examined on two occasions by four experienced pathologists. Analysis by observed agreement and kappa statistics showed maximal tumour thickness to be the best reproducible variable, with ulceration the second best. Regression was the least reproducible, with level of invasion and type of melanoma in the mid range. Intra-observer variation was uniformly less than inter-observer variation for each variable. For tumour thickness a variance component analysis was done to quantify the variability further. The clinician should not base his choice of treatment entirely on the microscopic classification but take into consideration the clinical course and appearance of the tumour.

Inter-observer variability among pathologists' evaluation of malignant melanoma: effects upon an analytic study

This study examined whether inter-observer variability in rating tumor characteristics affected results of an investigation of surveillance bias and malignant melanoma at the Lawrence Livermore National Laboratory. The 20 cases from the Laboratory and their 36 non-Laboratory controls belonged to the same pre-paid health plan and were diagnosed with melanoma between 1970 and 1984. Tumors were independently and then jointly rated by three dermatopathologists blind to the subjects' Laboratory status. The mean difference between the reviewers and the consensus reading for tumor thickness was small, ranging from -0.06 mm (95% confidence interval [CI]--0.12, 0.00) to 0.00 mm (95% CI--0.07, 0.07). Agreement was much lower for histologic type (kappa = 0.48, 95% CI 0.37, 0.58). Because the inter-observer variability, the study's hypothesis was rejected by analyses based on data from the consensus reading and two reviewers, but not on data from the third reviewer. These findings suggest that epidemiologists using data subject to inter-observer variability may want to employ consensus instead of individual ratings.