Tumor mitotic rate is an independent predictor of survival for nonmetastatic melanoma

The Prognostic Value of Proliferative Activity in Cutaneous Melanoma: A Pilot Study Evaluating the Mitotic Rate and Ki67 Index to Predict Patient Outcomes

Proliferative activity in cutaneous melanomas can be appreciated both histopathologically by counting mitotic figures and immunohistochemically through the Ki67 index, but the prognostic value of each method is still a matter of debate. In this context, we performed a retrospective study on 33 patients diagnosed with cutaneous melanomas between 2013 and 2018 in order to evaluate progression-free survival and overall survival. Multivariate Cox proportional hazards regression was performed by considering both clinical histopathological and immunohistochemical features. The mitotic rate was significantly independently associated with both outcomes, while the Ki67 index was not an independent prognostic factor. However, the Ki67 predictive accuracy could be improved by establishing both a cut-off value and a standardized protocol for evaluating its expression. Until these desiderata are met, the mitotic rate remains superior to the Ki67 index for predicting prognosis in cutaneous melanomas, as also has the advantage of being easily interpreted in a standard histopathological examination regardless of the pathologist's experience and with no further financial expenses. Importantly, this is one of very few articles that has shown perineural invasion to be an independent prognostic factor for both progression-free survival and overall survival in cutaneous melanomas. As a consequence, this parameter should become a mandatory feature in the histopathological evaluation of cutaneous melanomas as it can improve the identification of patients who are at high risk for disease progression.

Could the mitotic count improve personalized prognosis in melanoma patients?

A number of studies have indicated that the mitotic rate may be a predictive factor for poor prognosis in melanoma patients. The aim of this study was to investigate whether the mitotic rate is associated with other prognostic clinical and anatomopathological characteristics. After adjusting for other anatomopathological characteristics, we then verified the prognostic value of the number of mitoses, determining in which population subgroup this variable may have greater prognostic significance on 3-year mortality. The Veneto Cancer Registry (Registro Tumori del Veneto-RTV), a high-resolution population-based dataset covering the regional population of approximately 4.9 million residents, served as the clinical data source for the analysis. Inclusion criteria included all incident cases of invasive cutaneous malignant melanoma recorded in the RTV in 2015 (1,050 cases) and 2017 (1,205 cases) for which the number of mitoses was available. Mitotic classes were represented by Kaplan-Meier curves for short-term overall survival. Cox regression calculated hazard ratios in multivariable models to evaluate the independent prognostic role of different mitotic rate cut-offs. The results indicate that the mitotic rate is associated with other survival prognostic factors: the variables comprising the TNM stage (e.g., tumor thickness, ulceration, lymph node status and presence of metastasis) and the characteristics that are not included in the TNM stage (e.g., age, site of tumor, type of morphology, growth pattern and TIL). Moreover, this study demonstrated that, even after adjusting for these prognostic factors, mitoses per mm2 are associated with higher mortality, particularly in T2 patients. In conclusion, these findings revealed the need to include the mitotic rate in the histological diagnosis because it correlates with the prognosis as an independent factor. The mitotic rate can be used to develop a personalized medicine approach in the treatment and follow-up monitoring of melanoma patients.

Scalp Melanoma: A High-Risk Subset of Cutaneous Head and Neck Melanomas with Distinctive Clinicopathological Features

Scalp melanomas (SM) have been previously associated with poor overall and melanoma-specific survival rates. The aim of this study was to describe and compare the clinicopathological characteristics and survival outcomes of SM and non-scalp cutaneous head and neck melanoma (CHNM). An observational multi-center retrospective study was designed based on patients with CHNM followed in two tertiary care hospitals. A hundred and fifty-two patients had CHNM, of which 35 (23%) had SM. In comparison with non-scalp CHNM, SM were more frequently superficial spreading and nodular subtypes, had a thicker Breslow index median (2.1 mm vs. 0.85 mm), and a higher tumor mitotic rate (3 vs. 1 mitosis/mm2) (p < 0.05). SM had a higher risk of recurrence and a higher risk of melanoma-specific death (p < 0.05). In the multivariate analysis, scalp location was the only prognostic factor for recurrence, and tumor mitotic rate was the only prognostic factor for melanoma-specific survival. We encourage routinely examining the scalp in all patients, especially those with chronic sun damage.

Histopathologic abundance of pigmentation correlates with disease-specific survival in malignant melanoma but is not independent of current AJCC pT stage

The increasing number of melanoma patients makes it necessary to develop best possible strategies for prognosis assessment in order to recommend appropriate therapy and follow-up. The prognostic significance of tumor cell pigmentation has not been fully elucidated. Hematoxylin and eosin (H&E)-stained sections of 775 melanomas diagnosed between 2012 and 2015 were independently assessed for melanin pigment abundance by two investigators, and the impact on melanoma-specific survival was calculated. Unpigmented melanomas (n = 99) had a melanoma-specific survival of 67.7%, melanomas with moderate pigmentation (n = 384) had a melanoma-specific survival of 85.9%, and strongly pigmented melanomas (n = 292) had a melanoma-specific survival of 91.4% (p < .001). In an analysis of melanoma-specific survival adjusted for pT stage and pigmentation, we found a nonsignificant impact of pigmentation abundance with a hazard ratio of 1.277 (p = .74). The study presented here provides evidence in a German cohort that patients with pigmented melanomas have a more favorable prognosis than those diagnosed with nonpigmented melanomas. Moreover, the abundance of pigmentation already seems to provide a first prognostic estimate. However, it does not appear to provide significant additional value for prognostic assessment according to the AJCC 2017 pT classification.

Association of Excision Margin Size With Local Recurrence and Survival in Patients With T1a Melanoma at Critical Structures

Importance

Melanoma guidelines recommend surgical excision with 10-mm margins for T1 melanoma. However, this procedure may be problematic at sites close to critical structures such as the scalp, face, external genitalia, acral, periumbilical, and perineal areas.

Objective

To compare outcomes of wide (10-mm margins) vs narrow (5-mm margins) excision in patients with T1a melanoma near critical structures.

Design, Setting, and Participants

This cohort study was a retrospective comparison of 1341 consecutive patients aged 18 years or older from the National Cancer Institute of Milan, Italy, diagnosed between 2001 and 2020 with T1a cutaneous melanoma close to critical structures who accepted wide excision vs narrow excision.

Exposures

Local recurrence and melanoma-specific mortality (MSM) rates with 5-mm vs 10-mm excision margins.

Main Outcomes and Measures

The primary aim of the study was to ascertain whether a narrower (5-mm) vs wider (10-mm) excision margin was associated with local recurrence and MSM. The secondary aim was to compare the need for reconstructive surgery in the groups defined by excision margin width. Between April 28 and August 7, 2022, associations were assessed by weighted Cox and Fine-Gray univariable and multivariable models.

Results

A total of 1179 patients met the inclusion criteria (median [IQR] age, 50.0 [39.5-63.0] years; female, 610 [51.7%]; male, 569 [49.3%]). Six hundred twenty-six patients (53.1%) received a wide excision (434 [69.3%] with linear repair and 192 [30.7%] with flap or graft reconstruction) and 553 (46.9%) received a narrow excision (491 [88.8%] with linear repair and 62 [11.2%] with flap or graft reconstruction). The weighted 10-year MSM was 1.8% (95% CI, 0.8%-4.2%) in the wide group and 4.2% (95% CI, 2.2%-7.9%) in the narrow group; the weighted 10-year local recurrence rate was 5.7% (95% CI, 3.9%-8.3%) in the wide group and 6.7% (95% CI, 4.7%-9.5%) in the narrow group. Breslow thickness greater than 0.4 mm (subdistribution hazard ratio [sHR] for 0.6 vs 0.4 mm, 2.42; 95% CI, 1.59-3.68; P < .001) and mitotic rate greater than 1/mm2 (sHR for a single increment, 3.35; 95% CI, 2.59-4.32; P < .001) were associated with worse MSM. Multivariable analysis showed that acral lentiginous melanoma, lentigo maligna melanoma, and increasing Breslow thickness were associated with a higher incidence of local recurrence.

Conclusions and Relevance

The study's findings suggest that local excision with 5-mm margins for T1a melanoma may not be associated with an increased risk of local recurrence. Breslow thickness greater than 0.4 mm, mitotic rate greater than 1/mm2, and acral lentiginous melanoma and lentigo maligna melanoma subtypes were associated with a higher risk of recurrence. These findings may be useful for future melanoma treatment guidelines.

Per- and polyfluoroalkyl substances (PFAS) exposure in melanoma patients: a retrospective study on prognosis and histological features

Per- and polyfluoroalkyl substances (PFAS) are endocrine disrupting chemicals which could be associated with cancer development, such as kidney and testicular cancers, pancreatic and hepatocellular carcinoma and thyroid tumor. Available scientific literature offers no information on the role of PFAS in melanoma development/progression. Since 1965, a massive environmental contamination by PFAS has occurred in northeastern Italy. This study compared histopathology and prognosis between melanoma patients exposed (n = 194) and unexposed (n = 488) to PFAS. All patients were diagnosed and/or treated for melanoma at the Veneto Oncological Institute and the University Hospital of Padua (Italy) in 1998-2014. Patients were categorized in exposed or unexposed groups according to their home address and the geographical classification of municipalities affected by PFAS contamination as provided by Veneto Government in 2018. Presence of mitoses was found in 70.5% of exposed patients and 58.7% of unexposed patients (p = 0.005). Median follow-up was 90 months (IQR 59-136). 5-year overall survival was 83.7% in exposed patients and 88.0% in unexposed patients (p = 0.20); 5-year disease-specific survival was 88.0% in exposed patients and 90.9% in unexposed patients (p = 0.50); 5-year disease-free survival was 83.8% in exposed patients and 87.3% in unexposed patients (p = 0.20). Adjusting for imbalanced characteristics at baseline (presence of mitoses), survival was not statistically different between exposed and unexposed patients (overall survival: HR 1.10, 95% CI 0.77 to 1.58, p = 0.57; disease-specific survival: HR 0.99, 95% CI 0.62 to 1.59, p = 0.99; disease-free survival: HR 1.10, 95% CI 0.74 to 1.64, p = 0.62). Although the magnitude of PFAS exposure was not quantifiable, our findings suggested that exposure to PFAS was associated with higher level of mitosis in melanoma patients, but this did not translate into a survival difference. Further studies are required to investigate this relationship and all effects of PFAS on prognosis.

Ulceration vs Mitosis in Cutaneous Melanoma: which is Superior for Predicting Prognosis Across Clinical Stages?

Ulceration and high mitosis are considered among the major unfavorable prognostic factors in the survival of cutaneous melanoma patients. The aim of this study was to investigate the clinical significance of these parameters and to compare them to see which one is superior to predicting prognosis across all clinical stages of melanoma. A total of 1,074 melanomas were analyzed retrospectively. Tumor ulceration was found to be limited to the local stage for predicting survival, whereas, mitosis maintained its prognostic strength for predicting survival across all clinical stages. Furthermore, no survival differences were observed between ulceration and mitosis across clinical stages.

Development of an Image Analysis-Based Prognosis Score Using Google's Teachable Machine in Melanoma

BACKGROUND

The increasing number of melanoma patients makes it necessary to establish new strategies for prognosis assessment to ensure follow-up care. Deep-learning-based image analysis of primary melanoma could be a future component of risk stratification.

OBJECTIVES

To develop a risk score for overall survival based on image analysis through artificial intelligence (AI) and validate it in a test cohort.

METHODS

Hematoxylin and eosin (H&E) stained sections of 831 melanomas, diagnosed from 2012-2015 were photographed and used to perform deep-learning-based group classification. For this purpose, the freely available software of Google's teachable machine was used. Five hundred patient sections were used as the training cohort, and 331 sections served as the test cohort.

RESULTS

Using Google's Teachable Machine, a prognosis score for overall survival could be developed that achieved a statistically significant prognosis estimate with an AUC of 0.694 in a ROC analysis based solely on image sections of approximately 250 × 250 µm. The prognosis group "low-risk" (n = 230) showed an overall survival rate of 93%, whereas the prognosis group "high-risk" (n = 101) showed an overall survival rate of 77.2%.

CONCLUSIONS

The study supports the possibility of using deep learning-based classification systems for risk stratification in melanoma. The AI assessment used in this study provides a significant risk estimate in melanoma, but it does not considerably improve the existing risk classification based on the TNM classification.

Prognosis for Cutaneous Melanoma by Clinical and Pathological Profile: A Population-Based Study

Introduction

Among white people, the incidence of cutaneous malignant melanoma (CMM) has been increasing steadily for several decades. Meanwhile, there has also been a significant improvement in 5-year survival among patients with melanoma. This population-based cohort study investigates the five-year melanoma-specific survival (MSS) for all melanoma cases recorded in 2015 in the Veneto Tumor Registry (North-Est Italian Region), taking both demographic and clinical-pathological variables into consideration.

Methods

The cumulative melanoma-specific survival probabilities were calculated with the Kaplan-Meier method, applying different sociodemographic and clinical-pathological variables. Cox’s proportional hazards model was fitted to the data to assess the association between independent variables and MSS, and also overall survival (OS), calculating the hazard ratios (HR) relative to a reference condition, and adjusting for sex, age, site of tumor, histotype, melanoma ulceration, mitotic count, tumor-infiltrating lymphocytes (TIL), and stage at diagnosis.

Results

Compared with stage I melanoma, the risk of death was increased for stage II (HR 3.31, 95% CI: 0.94-11.76, p=0.064), almost ten times higher for stage III (HR 10.51, 95% CI: 3.16-35.02, p<0.001), and more than a hundred times higher for stage IV (HR 117.17, 95% CI: 25.30-542.62, p<0.001). Among the other variables included in the model, the presence of mitoses and histological subtype emerged as independent risk factors for death.

Conclusions

The multivariable analysis disclosed that older age, tumor site, histotype, mitotic count, and tumor stage were independently associated with a higher risk of death. Data on survival by clinical and morphological characteristics could be useful in modelling, planning, and managing the most appropriate treatment and follow-up for patients with CMM.

Different mitotic rates are associated with different prognostic factors, relapses, and survival rates in melanoma

BACKGROUND

Mitotic rate is one of the major prognostic factors in melanoma.

OBJECTIVE

To investigate the significance of mitotic rate and possible impacts of clinicopathological factors on the course of all staged melanoma patients.

METHODS

A total number of 970 melanoma patients were analyzed. Mitotic rates were grouped for analysis as follows: 0-1, 1.1-4.9, 5-9.9, and ≥10 mitoses/mm² .

RESULTS

Melanomas with higher mitotic rates were more likely to be associated with nodular histology (P = 0.0001), higher Clark level (P = 0.0001), thick Breslow depth (P = 0.0001), ulceration (P = 0.0001), vertical growth pattern (P = 0.0001), neurotropism (P = 0.04), lymphovascular invasion (P = 0.01), de novo melanoma (P = 0.0001), absence of tumor infiltrating lymphocytes (P = 0.02), advanced stage (P = 0.0001), and relapse (P = 0.0001). The 5-year overall survival (OS) rate of all patients was 68.7%, and it decreased significantly from 87% in melanomas with 0-1 mitoses/mm² to 65.2%, 56.6%, and 50.4% in melanomas with 1.1-4.9, 5-9.9, and ≥10 mitoses/mm² , respectively (P = 0.0001). Age (P = 0.04), gender (P = 0.03), histology (P = 0.0001), Clark level (P = 0.001), T-stage (P = 0.003), ulceration (0.006), node involvement (P = 0.0001), metastasis (P = 0.005), and relapse (P = 0.0001) were correlated with OS in 0-1 mitoses/mm² melanomas, whereas lymphovascular invasion (P = 0.0001), BRAF mutation (P = 0.01), metastasis (P = 0.0001), relapse (P = 0.0001), and relapse pattern (P = 0.005) were found significant for ≥10 mitoses/mm² melanomas.

CONCLUSION

Higher tumor mitotic rates associated with known histopathological and clinical poor prognostic factors were found to be significantly independent predictors of early relapse and unfavorable survival for cutaneous melanoma patients. Moreover, different prognostic variables were found to be affecting survivals in melanoma patients with lower and higher mitosis.

BRAFV600E Mutant Allele Frequency (MAF) Influences Melanoma Clinicopathologic Characteristics

BACKGROUND

Cutaneous melanoma shows high variability regarding clinicopathological presentation, evolution and prognosis.

METHODS

Next generation sequencing was performed to analyze hotspot mutations in different areas of primary melanomas (MMp) and their paired metastases. Clinicopathological features were evaluated depending on the degree of variation of the BRAFV600E mutant allele frequency (MAF) in MMp.

RESULTS

In our cohort of 14 superficial spreading, 10 nodular melanomas and 52 metastases, 17/24 (71%) melanomas had a BRAFV600E mutation and 5/24 (21%) had a NRASQ61 mutation. We observed a high variation of BRAFV600E MAF (H-BRAFV600E) in 7/17 (41%) MMp. The H-BRAFV600E MMp were all located on the trunk, had lower Breslow and mitotic indexes and predominantly, a first nodal metastasis. Regions with spindled tumor cells (Spin) and high lymphocytic infiltrate (HInf) were more frequent in the H-BRAFV600E patients (4/7; 57%), whereas regions with epithelial tumor cells (Epit) and low lymphocytic infiltrate (LInf) were predominant (6/10; 60%) and exclusive in the low BRAFV600E MAF variation tumors (L-BRAFV600E). The H-BRAFV600E/Spin/HInf MMp patients had better prognostic features and nodal first metastasis.

CONCLUSIONS

The H-BRAFV600E MMp were located on the trunk, had better prognostic characteristics, such as lower Breslow and mitotic indexes as well as high lymphocytic infiltrate.

Mitotic rate in node-positive stage III melanoma: it might be as important a prognostic factor as node number

BACKGROUND

Stage III melanoma is a heterogenous disease, and the number of tumor-involved lymph nodes is the most significantly unfavorable prognostic indicator for relapse and outcome. The aim of this study is to investigate the possible effects of the various clinicopathological factors on the course of node-positive stage III disease.

METHODS

A total of 389 node-positive stage III cutaneous melanomas were included in the study and analyzed retrospectively. All underwent pathological nodal staging by sentinel lymph node biopsy or elective lymph node dissection.

RESULTS

The group was male-dominant (59%) and the median age was 50 years. The largest group of patients was N1 (n = 221, 56.8%) followed by N2 (n = 105, 27.0%) and N3 (n = 63, 16.2%). N1 melanomas were less frequently associated with relapses than melanomas with multiple lymph node metastases (P = 0.05). The 5-year relapse-free survival rate was 37.9%. The melanomas with multiple lymph nodes metastases (P = 0.01), higher mitotic rate (P = 0.005) and ulceration (P = 0.02) had worse RFS. In the multivariate analysis only the significances of the N2-N3 stage (P = 0.016) and higher mitosis (P = 0.012) persisted. The severe lymph node metastasis (N2-N3) was associated with a higher mortality rate in comparison with the single nodal involvement (P = 0.05). The 5-year overall survival rate was 52.1%. Presence of relapse (P = 0.0001), higher mitotic rate (P = 0.03) and N2-N3 stage (P = 0.04) were inversely correlated with the overall survival. When relapse was included in the multivariate analysis, it was the only significant prognostic factor on survival (P = 0.0001), whereas mitosis became the only significant factor on survival with the exclusion of relapse from the multivariate analysis (P = 0.031).

CONCLUSION

In node-positive stage III melanoma, tumor mitotic rate might be just as significant a prognostic indicator as the metastatic lymph node number.

Sex-specific survival benefit in early skin melanoma based on 8th AJCC edition: an analysis of data from the Surveillance, Epidemiology, and End Results (SEER) database

Background

Females have been found to have a survival benefit over males in past studies. However, in early melanoma patients, this benefit occurred in only those aged >60 years. The 8th edition of the American Joint Committee on Cancer (AJCC) readjusted the melanoma staging system, specifically stage I. This study aims to verify whether the sex-specific benefit in females exists in different age groups according to the 8th edition of the staging system.

Methods

We collected the data of individuals diagnosed with skin melanoma between 2004 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database. Based on the 8th edition of the melanoma staging system, patients diagnosed with pathological stage T1a-T3a, N0 and M0 melanoma were enrolled.

Results

A total of 115,576 patients, including 62,938 male patients and 52,638 female patients, were enrolled in this study. The survival rates of males and females in each stage from IA–IIA were significantly different (P<0.001). In further analyses of each age group, it was found that the proportions of patients with stages IA, IB and IIA were significantly different in each age group. Cox analysis showed that females with stage IA in all age groups benefited significantly, but those in stage IB benefited only when they were aged >60 years. In stage IIA patients, there were significant differences between the <50 and 61–70 years age groups.

Conclusions

Based on data from the SEER database, we found that according to the 8th edition of the AJCC melanoma staging system, females had a higher survival rate than males, and this difference was significant in all age groups in the stage IA group but fluctuated with age in the stage IB and IIA groups.

Epidemiology and survival outcomes in stages II and III cutaneous melanoma: a systematic review

Aim

Management of cutaneous melanoma (CM) is continually evolving with adjuvant treatment of earlier stage disease. The aim of this review was to identify published epidemiological data for stages II-III CM.

Materials & methods

Systematic searches of Medline and Embase were conducted to identify literature reporting country/region-specific incidence, prevalence, survival or mortality outcomes in stage II and/or III CM. Screening was carried out by two independent reviewers.

Results & conclusion

Of 41 publications, 14 described incidence outcomes (incidence rates per stage were only reported for US and Swedish studies), 33 reported survival or mortality outcomes and none reported prevalence data. This review summarizes relevant data from published literature and highlights an overall paucity of epidemiological data in stages II and III CM.

Morphologic Forms and Classification of Dermal Mitotic Figure Density in Primary Cutaneous Melanoma: A Retrospective Study

New American Joint Committee on Cancer eighth edition staging parameters have removed mitotic rate as a stage T1 category criterion, but it remains embedded in the synopsis of primary cutaneous melanoma (CM). A paucity of data is available, characterizing atypical mitotic forms in CM. In this study, we classify the various morphologic forms of atypical mitoses, characterize mitotic figure density, and examine the correlation between atypical mitotic figures and Breslow depth. We performed a retrospective study of 185 thick (>0.8 mm) and thin (<0.8 mm) CM specimens. Metaphase mitotic figures represented the highest percentage of total mitotic figures in cases of thick melanoma (40%) and were the second most common in thin melanoma (18%). The average Breslow depth for melanoma harboring starburst mitoses was 2.85 mm, compared with the average Breslow depth of all thick melanoma cases, 1.88 mm. The average thickness of melanoma cases containing tripolar mitoses was 2.28 mm. Breslow depth correlated with the number of atypical mitotic figures in both thick and thin melanomas (the Pearson correlation test, r = +0.18, P < 0.01). Metaphase and prophase mitoses are a common finding in both thick and thin melanomas. Although atypical mitoses were indiscriminate, starburst and tripolar (ie, multipolar) mitoses were only inherent to cases of thick melanoma (stage T3). In sum, our study reveals a parallel relationship between the density of atypical mitotic figures and Breslow depth.

A novel RNA sequencing-based prognostic nomogram to predict survival for patients with cutaneous melanoma: Clinical trial/experimental study

BACKGROUND

Plenty of evidence has suggested that long non-coding RNAs (lncRNAs) have played a vital part may act as prognostic biomarkers in a variety of cancers. The aim of this study was to screen survival-related lncRNAs and to construct a lncRNA-based prognostic model in patients with cutaneous melanoma (CM).

METHODS

We obtained lncRNAs expression profiles and clinicopathological data from the Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) databases. A lncRNA-based prognostic model was established in training set. The established prognostic model was evaluated, and validated in the validation set. Then, a prognostic nomogram combining the lncRNA-based risk score and clinicopathological characteristics was developed in training set, and assessed in the validation set. The accuracy of the model was evaluated by the discrimination and calibration plots.

RESULTS

A total of 212 lncRNAs were identified to be differentially expressed in CM. After univariate analysis, LASSO penalized regression analysis, and multivariate analysis, 3 lncRNAs were used to construct risk score model. The proposed risk score model could divide patients into high-risk and low-risk groups with significantly different survival in both training set and validation set. The ROC curve showed good performance in survival prediction in both sets. Furthermore, the nomogram for predicting 3-, 5-, and 10-year OS was established based on lncRNA-based risk score and clinicopathologic factors. The prognostic accuracy of the risk model was confirmed by the discrimination and calibration plots in both training set and validation set.

CONCLUSIONS

We established a novel three lncRNA-based risk score model and nomogram to predict overall survival of CM. The proposed nomogram may provide information for individualized treatment in CM patients.

Pathology of Melanoma

Melanoma is an aggressive malignancy arising from melanocytes in the skin and rarely in extracutaneous sites. The understanding of pathology of melanoma has evolved over the years, with the initial classifications based on the clinical and microscopic features to the current use of immunohistochemistry and genetic sequencing. The depth of invasion and lymph node metastasis are still the most important prognostic features of melanoma. Other important prognostic features include ulceration, lymphovascular invasion, mitosis, and tumor-infiltrating lymphocytes. This article reviews the pathology of melanoma and its precursor lesions, along with the recent advances in pathologic diagnosis of melanoma.

Mitotic rate as an important prognostic factor in cutaneous malignant melanoma

BACKGROUND

Recently, the quantification of mitoses in cutaneous melanoma has been discharged from the main prognostic variables of the TNM classification.

OBJECTIVE

To investigate the prognostic value of the presence of mitoses in primary cutaneous melanoma and to establish the number of mitoses per mm2 that may have prognostic significance.

METHODS

A retrospective observational study was performed on 141 patients treated for cutaneous melanoma, who were assessed by the same pathologist, and who had a minimum follow-up of 2 years. Clinical, epidemiological, histopathological and follow-up variables were gathered and compared with the number of mitoses to distinguish the significance of differences by means of univariate, multivariate, and survival analyses.

RESULTS

The cut-off level related to a better sensitivity and specificity was 1.50 mitoses per mm2. The presence of two or more mitoses/mm2 showed a better relationship with prognostic variables and both the overall and disease-free survival than the presence of 1 or more mitoses/mm2. This happens especially in melanomas thicker than 0.8 mm and it could affect the staging in cases with Breslow between 1 and 2 mm.

CONCLUSIONS

A mitotic rate of two or more mitoses per mm2 in cutaneous melanoma should be considered as a more accurate prognostic factor than one or more mitoses per mm2, particularly in tumors equal or greater than 0.8 mm in thickness.