Influence of regression, its extent and tumor-infiltrating lymphocytes on sentinel node status, relapse, and survival in a 10-year retrospective study of melanoma patients

This case-control study seeks to investigate the influence of histological findings, specifically regression, its extent and tumor-infiltrating lymphocyte (TILs), on result of sentinel lymph node (SLN) biopsy, 5-year melanoma-specific survival (MSS), and relapse-free survival (RFS). We included all patients with cutaneous melanoma who underwent SLN biopsy at the Melanoma Center of the University of Brescia, following the Italian Association of Medical Oncology National guidelines from January 2008 to August 2018. Regression and its extent (<75 or ≥75%) and the presence of TILs were reevaluated by a trained dermatopathologist, adhering to the 2017 College of American Pathologists Cancer Protocol for Skin Melanoma. These patients were followed up for 5 years. Our study uncovered significant associations between regression and male sex ( P  < 0.05), melanoma location on the trunk, upper limbs, and back ( P  = 0.001), ulceration ( P  < 0.05), lower Breslow thickness ( P  = 0.001), and the presence of lymphocytic infiltration (both brisk and nonbrisk) ( P  < 0.001). Regression and its extent, however, did not appear to affect SLN positivity ( P  = 0.315). Similarly, our data did not reveal a correlation between TILs and result of SLN biopsy ( P  = 0.256). When analyzing MSS and RFS in relation to the presence or absence of regression and TILs, no statistically significant differences were observed, thus precluding the need for logistic regression and Kaplan-Meier curve analysis. This study's findings underscore that regression and TILs do not appear to exert an influence on sentinel lymph node status,, MSS, or RFS in our cohort of patients.

Association of miR-146a-5p and miR-21-5p with Prognostic Features in Melanomas

BACKGROUND

Cutaneous melanoma (CM) is one of the most lethal tumors among skin cancers and its incidence is rising worldwide. Recent data support the role of microRNAs (miRNAs) in melanoma carcinogenesis and their potential use as disease biomarkers.

METHODS

We quantified the expression of miR-146a-5p and miR-21-5p in 170 formalin-fixed paraffin embedded (FFPE) samples of CM, namely 116 superficial spreading melanoma (SSM), 26 nodular melanoma (NM), and 28 lentigo maligna melanoma (LMM). We correlated miRNA expression with specific histopathologic features including Breslow thickness (BT), histological subtype, ulceration and regression status, and mitotic index.

RESULTS

miR-146a-5p and miR-21-5p were significantly higher in NM compared to SSM and LMM. The positive correlation between miR-146a-5p and miR-21-5p expression and BT was confirmed for both miRNAs in SSM. Considering the ulceration status, we assessed that individual miR-21-5p expression was significantly higher in ulcerated CMs. The increased combined expression of the two miRNAs was strongly associated with ulceration (p = 0.0093) and higher mitotic rate (≥1/mm2) (p = 0.0005). We demonstrated that the combination of two-miRNA expression and prognostic features (BT and ulceration) can better differentiate cutaneous melanoma prognostic groups, considering overall survival and time-to-relapse clinical outcomes. Specifically, miRNA expression can further stratify prognostic groups among patients with BT ≥ 0.8 mm but without ulceration. Our findings provide further insights into the characterization of CM with specific prognostic features. The graphical abstract was created with BioRender.com.

Histopathologic regression in patients with primary cutaneous melanoma undergoing sentinel lymph node biopsy is associated with favorable survival and, after metastasis, with improved progression-free survival on immune checkpoint inhibitor therapy: A single-institutional cohort study

BACKGROUND

Histopathologic regression of cutaneous melanoma is considered a favorable prognostic factor, but its significance in clinical practice remains controversial.

OBJECTIVE

To investigate the prognostic importance of regression in patients with primary cutaneous melanoma undergoing sentinel lymph node (SLN) biopsy and to assess its significance in patients progressing to an unresectable stage requiring systemic therapy.

METHODS

We retrospectively reviewed patients with newly diagnosed melanoma undergoing SLN biopsy between 2010 and 2015 and available information on histopathologic regression (n = 1179). Survival data and associations of clinical variables with SLN status were assessed.

RESULTS

Patients with regressive melanoma showed favorable relapse-free (hazard ratio [HR], 0.52; P = .00013), distant metastasis-free (HR, 0.56; P = .0020), and melanoma-specific survival (HR, 0.35; P = .00053). Regression was associated with negative SLN (odds ratio, 0.48; P = .0077). In patients who progressed to an unresectable stage, regression was associated with favorable progression-free survival under immune checkpoint inhibition (HR, 0.43; P = .031) but not under targeted therapy (HR, 1.14; P = .73) or chemotherapy (HR, 3.65; P = .0095).

LIMITATIONS

Retrospective, single-institutional design.

CONCLUSIONS

Regression of cutaneous melanoma is associated with improved prognosis in patients eligible for SLN biopsy as well as in patients with unresectable disease receiving systemic therapy with immune checkpoint inhibitors.

Acute regression of a melanocytic neoplasm

Immune-mediated regression of melanocytic neoplasms is predominantly lymphocytic, driven by CD8+ anti-tumoral T-cells and, rarely, natural killer cells. Histopathologic features of regression include effacement of the epidermis, replacement of tumor cells by a fibrotic stroma, varying degrees of chronic inflammation (usually lymphocytes) and melanophages, as well as vascular ectasia and angioplasia. The understanding of regression and the complex immune response in melanoma has led to the development of targeted immunotherapy in melanoma. Here, we report a case of near-complete regression of a melanocytic neoplasm associated with neutrophilic and eosinophilic inflammation, suggesting a non-traditional pathway of regression that has yet to be explored.

Multiple Primary Melanomas: Retrospective Review in a Tertiary Care Hospital

Multiple primary melanomas (MPM) refer to the occurrence of more than one synchronous or metachronous melanoma in the same individual. The aim of this study was to identify the frequency of MPM and describe the clinical and histopathologic characteristics of patients with MPM. An observational single-center retrospective study was designed based on a cohort of melanoma patients followed in a tertiary care hospital. Fifty-eight (8.9%) patients developed MPM. Most patients were men (65.5%) and the median age at the time of diagnosis of the first melanoma was 71 years old. The median time of diagnosis of the second melanoma from the first melanoma was 10.9 months, and 77.6% of second melanomas were diagnosed within the first 5 years. In total, 29 (50%) and 28 (48.3%) first and second melanomas were located in the trunk, respectively. Concordance of anatomic site between primary and subsequent melanoma was found in 46.6% of the patients. Proportion of in situ melanomas was increasingly higher in subsequent melanomas (from 36.21% of first melanomas to 100% of fifth melanomas). An increasing rate of melanomas with histological regression was observed within subsequent melanomas (from 60.3% of first melanomas to 80% of third melanomas). Our results support the importance of careful long-term follow-up with total body examination in melanoma patients.

Sentinel Lymph Node Biopsy vs. Observation in Thin Melanoma: A Multicenter Propensity Score Matching Study

The therapeutic value of sentinel lymph node biopsy (SLNB) in thin melanoma remains controversial. The aim of this study is to determine the role of SLNB in the survival of thin melanomas (≤1 mm). A multicenter retrospective observational study was designed. A propensity score matching was performed to compare patients who underwent SLNB vs. observation. A multivariate Cox regression was used. A total of 1438 patients were matched by propensity score. There were no significant differences in melanoma-specific survival (MSS) between the SLNB and observation groups. Predictors of MSS in the multivariate model were age, tumor thickness, ulceration, and interferon treatment. Results were similar for disease-free survival and overall survival. The 5- and 10-year MSS rates for SLN-negative and -positive patients were 98.5% vs. 77.3% (p < 0.001) and 97.3% vs. 68.7% (p < 0.001), respectively. SLNB does not improve MSS in patients with thin melanoma. It also had no impact on DSF or OS. However, a considerable difference in MSS, DFS, and OS between SLN-positive and -negative patients exists, confirming its value as a prognostic procedure and therefore we recommend discussing the option of SLNB with patients.

Malignant melanoma of parotid glands from a neglected lesion: A case report

Observing a metastatic malignant melanoma and its primary lesion at the same time is rare. The histopathological detection of any unusual pigmented lesion is critical.

A Retrospective, Observational Analysis of Tumor Infiltrating Lymphocytes and Tumor Regression in Melanoma

BACKGROUND

Tumor infiltrating lymphocytes (TILs) and regression are thought to be distinct markers of the immune response to melanoma.

OBJECTIVE

This study sought to analyze the relationship of TIL grade and presence of regression to each other and to other prognostic histopathologic and clinical values in melanoma.

MATERIALS AND METHODS

A retrospective analysis was conducted using patients diagnosed with melanoma between 2013 and 2019 whose complete histopathologic reports were available.

RESULTS

Regression was seen in 48.9%, 30.1% and 37.9% of patients with brisk, non-brisk, and absent TILs respectively (P=0.019). Melanoma tumors with brisk TILs were found to have a lower Breslow thickness than those with non-brisk or absent (P= 0.001). Tumors with regression were also found to have lower Breslow thickness (P<0.001). Neither TIL grade nor regression were protective of nodal metastasis or associated with improved survival.

CONCLUSION

Brisk TILs have a positive association with thinner tumors and the presence of tumor regression relative to non-brisk or absent TILs. This may suggest a more robust immune response in tumors with brisk TILs. Further exploration of the interplay between TIL grade, lymphocyte cell subtype and lymphocyte density may help explain this finding.

Reporting regression in primary cutaneous melanoma. Part 1: history, histological criteria and pathogenesis

Regression is an important histopathological parameter reported for the diagnosis of primary cutaneous melanoma. Histological regression is defined by The College of American Pathologists as the replacement of tumour cells by lymphocytic inflammation, with attenuation of the epidermis, and nonlaminated dermal fibrosis with inflammatory cells, melanophagocytosis and telangiectasia. Histological regression may be reported as absent versus present and, if present, as complete, partial or segmental. The stages of histological regression are early, intermediate and late, depending on the extent of histological inflammation and fibrosis. Regression occurs when the host's immune system attacks primary melanocytic tumour cells via tumour-infiltrating lymphocytes, resulting in fibrosis. The immunological mechanisms driving complete, partial and segmental regression may vary. In this first part of this two-part review, we review the history, histological criteria and pathogenesis of regression in primary cutaneous melanoma, while in Part 2 we will review the effect of histological regression on prognosis, evaluation and management.

Is it Necessary to Perform Sentinel Lymph Node Biopsy in Thin Melanoma? A Retrospective Single Center Analysis

Sentinel lymph node biopsy (SLNB) is a standard procedure for regional lymph node staging and still has the most important prognostic value for the outcome of patients with thin melanoma. In addition to ulceration, SLNB had to be considered even for a single mitotic figure in thin (<1 mm) melanoma according to AJCC7th guideline, therefore, a retrospective review was conducted involving 403 pT1 melanoma patients. Among them, 152 patients suffered from pT1b ulcerated or mitotic rate ≥ 1/ mm2 melanomas according to the AJCC7th staging system. SLNB was performed in 78 cases, of which nine (11.5%) showed SLN positivity. From them, interestingly, we found a relatively high positive sentinel rate (6/78-8%) in the case of thin primary melanomas ˂0.8 mm. Moreover, the presence of regression increased the probability of sentinel positivity by 5.796 fold. After reassessing pT stage based on the new AJCC8th, 37 pT1b cases were reordered into pT1a category. There was no significant relation between other characteristics examined (age, gender, Breslow, Clark level, and mitosis index) and sentinel node positivity. Based on our data, we suggest that mitotic rate alone is not a sufficiently powerful predictor of SLN status in thin melanomas. If strict histopathological definition criteria are applied, regression might be an additional adverse feature that aids in identifying T1 patients most likely to be SLN-positive. After reassessing of pT1b cases according to AJCC8th regression proved to be independent prognostic factor on sentinel lymph node positivity. Our results propose that sentinel lymph node biopsy might also be considered at patients with regressive thin (˂0.8 mm) melanomas.

Functional heterogeneity of lymphocytic patterns in primary melanoma dissected through single-cell multiplexing

In melanoma, the lymphocytic infiltrate is a prognostic parameter classified morphologically into 'brisk', 'non-brisk' and 'absent' entailing a functional association that has never been proved. Recently, it has been shown that lymphocytic populations can be very heterogeneous, and that anti-PD-1 immunotherapy supports activated T cells. Here, we characterize the immune landscape in primary melanoma by high-dimensional single-cell multiplex analysis in tissue sections (MILAN technique) followed by image analysis, RT-PCR and shotgun proteomics. We observed that the brisk and non-brisk patterns are heterogeneous functional categories that can be further sub-classified into active, transitional or exhausted. The classification of primary melanomas based on the functional paradigm also shows correlation with spontaneous regression, and an improved prognostic value when compared to that of the brisk classification. Finally, the main inflammatory cell subpopulations that are present in the microenvironment associated with activation and exhaustion and their spatial relationships are described using neighbourhood analysis.

Current controversies in early-stage melanoma: Questions on incidence, screening, and histologic regression

In the first article in this continuing medical education series we review controversies and uncertainties relating to the epidemiology and initial diagnosis of localized cutaneous melanoma (ie, stage 0, I, or II). Many of these issues are unsettled because of conflicting evidence. Melanoma incidence appears to be increasing, yet its basis has not been fully explained. Despite the advantages of early detection, the US Preventive Services Task Force does not recommend skin screening for the general population. Occasionally, biopsy specimens of melanoma will show histologic regression, but the prognostic importance of this phenomenon is uncertain. Some practitioners recommend obtaining a sentinel lymph node biopsy specimen for thin melanomas showing regression, although this histologic finding is not part of the staging system for thin melanomas. Our goal is to provide the clinician who cares for patients with (or at risk for) melanoma with up-to-date contextual knowledge to appreciate the multiple sides of each controversy so that they will be better informed to discuss these issues with their patients and their families.

Vertical Growth Phase as a Prognostic Factor for Sentinel Lymph Node Positivity in Thin Melanomas: A Systematic Review and Meta-Analysis

BACKGROUND

The 2010 American Joint Committee on Cancer guidelines recommended consideration of sentinel lymph node biopsy for thin melanoma (Breslow thickness <1.0 mm) with aggressive pathologic features such as ulceration and/or high mitotic rate. The therapeutic benefit of biopsy-based treatment remains controversial. The authors conducted a meta-analysis to estimate the risk and outcomes of sentinel lymph node positivity in thin melanoma, and examined established and potential novel predictors of positivity.

METHODS

Three databases were searched by two independent reviewers for sentinel lymph node positivity in patients with thin melanoma. Study heterogeneity, publication bias, and quality were assessed. Data collected included age, sex, Breslow thickness, mitotic rate, ulceration, regression, Clark level, tumor-infiltrating lymphocytes, and vertical growth phase. Positivity was estimated using a random effects model. Association of positivity and clinicopathologic features was investigated using meta-regression.

RESULTS

Ninety-three studies were identified representing 35,276 patients with thin melanoma who underwent sentinel lymph node biopsy. Of these patients, 952 had a positive sentinel lymph node biopsy, for an event rate of 5.1 percent (95 percent CI, 4.1 to 6.3 percent). Significant associations were identified between positivity and Breslow thickness greater than 0.75 mm but less than 1.0 mm, mitotic rate, ulceration, and Clark level greater than IV. Seven studies reported on vertical growth phase, which was strongly associated with positivity (OR, 4.3; 95 percent CI, 2.5 to 7.7).

CONCLUSIONS

To date, this is the largest meta-analysis to examine predictors of sentinel lymph node biopsy positivity in patients with thin melanoma. Vertical growth phase had a strong association with biopsy positivity, providing support for its inclusion in standardized pathologic reporting.

Acquired disorders with depigmentation: A systematic approach to vitiliginoid conditions

Acquired disorders with depigmentation are commonly encountered by dermatologists and present with a wide differential diagnosis. Vitiligo, the most common disorder of acquired depigmentation, is characterized by well-defined depigmented macules and patches. Other conditions, such as chemical leukoderma, can present with similar findings, and are often easily mistaken for vitiligo. Key clinical features can help differentiate between acquired disorders of depigmentation. The first article in this continuing medical education series focuses on conditions with a vitiligo-like phenotype. Early recognition and adequate treatment of these conditions is critical in providing appropriate prognostication and treatment.

Use of Lymph Node Ultrasound Prior to Sentinel Lymph Node Biopsy in 384 Patients with Melanoma: A Cost-Effectiveness Analysis

BACKGROUND AND OBJECTIVES

Locoregional lymph node ultrasound is not typically included in guidelines as part of the staging process prior to sentinel lymph node biopsy (SLNB). The objective of the present study was to make a clinical and economic analysis of lymph node ultrasound prior to SLNB.

MATERIALS AND METHODS

We performed a retrospective study of 384 patients with clinical stage I-II primary melanoma who underwent locorregional lymph node ultrasound (with or without ultrasound-guided biopsy) prior to SLNB between 2004 and 2015. We evaluated the reliability and cost-effectiveness of the strategy.

RESULTS

Use of locorregional lymph node ultrasound avoided SLNB in 23 patients (6%). Ultrasound had a sensitivity of 46% and specificity of 76% for the detection of metastatic lymph nodes that were not clinically palpable. False negatives were significantly more common in patients aged over 60 years and in tumors with a thickness of less than 2mm. The staging process using SLNB and ultrasound with ultrasound-guided biopsy produced an increase of €16.30 in the unit price. Our cost-effectiveness analysis identified the staging protocol with ultrasound and SLNB as the dominant strategy, with a lower cost-effectiveness ratio than the alternative, consisting of SLNB alone (8,095.24 vs. €28,605.00).

CONCLUSIONS

Ultrasound with ultrasound-guided biopsy for the diagnostic staging of melanoma prior to SLNB is a useful and cost-effective tool. This procedure does not substitute SLNB, though it does allow to avoid SLNB in a not insignificant proportion of patients.

Regression in primary cutaneous melanoma: etiopathogenesis and clinical significance

Though not required currently for staging, regression is a histopathologic parameter typically reported upon diagnosis of an invasive primary cutaneous melanoma. The studies examining the prognostic significance of regression in patient outcome have yielded controversial findings; likely because the definition and assessment of regression have not been consistent, in addition to subjectivity of pathologists' interpretation. Regression is histologically characterized by variable decrease in the number of melanoma cells accompanied by the presence of a host response consisting of dermal fibrosis, inflammatory infiltrate, melanophages, ectatic blood vessels, epidermal attenuation, and/or apoptosis of keratinocytes or melanocytes; the relative extent of these features depends on the stage of the regression. However, the magnitudes to which these individual changes must be present to meet the threshold of histologic regression have not been well defined or agreed upon, and thus, the definition and classification of histologic regression in melanoma varies considerably among institutions and even among individual pathologists. In order to determine the clinical significance of histologic analysis of regression, there is a compelling need for a universal scheme to objectively define and assess histologic regression in primary cutaneous melanoma, so that the biologic and prognostic significance of this process may be completely understood.Laboratory Investigation advance online publication, 27 February 2017; doi:10.1038/labinvest.2017.8.

Tumor Thickness and Mitotic Rate Robustly Predict Melanoma-Specific Survival in Patients with Primary Vulvar Melanoma: A Retrospective Review of 100 Cases

Purpose: Primary vulvar melanoma (PVM) is the second most common vulvar malignancy. Despite their distinct anatomic site and unique molecular-genetic alterations, PVMs are staged according to the American Joint Committee on Cancer (AJCC) guidelines for primary cutaneous melanomas (PCM). However, whether parameters derived for PCM also apply to PVM remain a critical yet largely unexplored clinical question. The objective of this study was to determine the parameters predictive of survival in PVM.Experimental Design: We retrospectively reviewed 100 patients with PVM and determined associations between clinical and histopathologic parameters and disease-specific survival (DSS) and overall survival (OS).Results: Univariate Cox regression analysis demonstrated older age (>56 years), greater tumor thickness, higher dermal mitotic rate, ulceration, lymphovascular invasion, perineural invasion, microscopic satellitosis, and absence of precursor nevus associated with decreased OS. Furthermore, age, midline, and/or multifocal involvement, greater tumor thickness, higher dermal mitotic rate, ulceration, lack of regression, lymphovascular invasion, perineural invasion, and microscopic satellitosis associated with decreased DSS. Multivariate analysis demonstrated tumor thickness, dermal mitotic rate, lymphovascular invasion, microscopic satellitosis, and absence of precursor nevus independently predicted shorter OS. Only tumor thickness and increased dermal mitotic rate (≥2/mm²) independently predicted reduced DSS. In comparison with the AJCC T-category, a novel, bivariate T-category based only on tumor thickness and dermal mitotic rate robustly predicted OS and DSS in our patient cohort.Conclusions: In the largest single institutional study of PVM, we demonstrate a combination of tumor thickness and mitotic rate comprise a simple but robust T-category to direct staging and prognosis. Clin Cancer Res; 23(8); 2093-104. ©2016 AACR.

Presence of histological regression as a prognostic factor in cutaneous melanoma patients

Regression is caused by a host immunological response primarily characterized by lymphocytic infiltration directed against melanoma cells. The prognostic significance of regression remains controversial in cutaneous melanoma patients. The aim of this study was to determine the clinical significance of the histological regression status in patients with cutaneous melanoma. A total of 664 patients with a pathologically confirmed cutaneous melanoma were enrolled into this study and were investigated retrospectively. The median age of the patients was 51 years, ranging in age from 16 to 104 years. The majority of them had lesions without regression (n=495; 74.5%) and others had lesions with regression (n=169; 25.5%). Melanoma patients with regression were more frequently males (60.1 vs 51.7%; P=0.038) and had axial localized lesions (67.5 vs 53.7%; P=0.002), superficial spreading histologic subtype (73.2 vs 49.1%; P=0.000), thin Breslow depth (<2 mm) (44.6 vs 33.5%; P=0.01), and the presence of tumor-infiltrating lymphocytes (74.4 vs 60.0%; P=0.001) than those without regression. However, regression was not significantly associated with age, Clark level, mitotic rate, ulceration, vertical growth phase, neurotropism, lymphovascular invasion, nor association with a pre-existing melanocytic nevus. Similarly, no significant correlations were found between regression and lymph node involvement, recurrence, nor metastasis of disease. Patients with, nodular pathology, advanced Clark invasion level (IV-V), thick Breslow depth (≥2 mm), high mitotic rate (>3/mm), ulceration, vertical growth phase, neurotropism, lymphovascular invasion, lymph node involvement, metastasis, and recurrence of disease, and male patients had poor prognostic variables for both relapse-free survival and overall survival. However, the presence of regression was not associated with relapse-free survival (P=0.093) nor overall survival (P=0.113) similar to other factors such as age, tumor localization, tumor-infiltrating lymphocytes, and association with a pre-existing melanocytic nevus. Similar insignificant P values were also observed in multivariate analyses (P=0.115 and 0.816, respectively). In conclusion, the presence of histological regression plays no prognostic role in nodal involvement nor survival in patients with cutaneous melanoma.

Regression in thin melanoma is associated with nodal recurrence after a negative sentinel node biopsy

Prognostic markers for nodal metastasis in thin melanoma patients are debated. We present a single institution study looking at factors predictive of nodal disease in thin melanoma patients. Retrospective review from 1997 to 2012 identified 252 patients with thin melanoma (≤1 mm) who underwent a sentinel lymph node biopsy (SLNB). Node‐positive patients included positive SLNB patients and negative SLNB patients who developed a nodal recurrence (false‐negative SLNB). Clinicopathologic characteristics were correlated with nodal status and outcome. Median follow‐up was 45.5 months. Twelve of 252 patients (4.8%) were node‐positive including six positive SLNB (2.4%) and six false‐negative SLNB (2.4%) patients. No clinicopathologic factors were significantly correlated with nodal disease. For the six false‐negative SLNB patients, median time to nodal recurrence was 37.5 months. Regression was seen in only 16% of cases, but the rate increased to 60% for false‐negative SLNB cases. Both age (odds ratio [OR]: 1.09, 95% CI: 1.01–1.17; P = 0.02) and regression (OR: 8.33, 95% CI: 1.34–52.63; P = 0.02) were significantly associated with nodal recurrence after a negative SLNB on univariable analysis. Nodal disease in thin melanoma patients was seen in 4.8% of cases. Although regression was not correlated with nodal metastasis, it was correlated with a false‐negative SLNB. Patients with thin melanoma and regression may need more intensive surveillance after a negative SLNB. Further study is needed to determine if the same immune mechanisms that result in regression in primary tumors also lead to regression in lymph nodes, which may decrease detection of melanoma nodal metastases.

Metastatic Malignant Melanoma of Parotid Gland with a Regressed Primary Tumor

Malignant melanoma of the parotid gland is often metastatic and mainly originates from malignant melanomas in the head and neck. Nevertheless, some malignant melanomas may metastasize and subsequently regress. Therefore, it may not be possible to observe a metastatic malignant melanoma and its primary melanoma simultaneously. The investigation of a patient's old photographs may help in the detection of preexisting and regressed pigmented lesions in the facial and neck regions.

BRAF and Epithelial-Mesenchymal Transition: Lessons From Papillary Thyroid Carcinoma and Primary Cutaneous Melanoma

The increased prevalence of BRAF mutations in thyroid carcinoma and primary cutaneous melanoma (PCM) hint that dysregulation of BRAF might contribute to the noted association between PCM and thyroid carcinoma. A recent study evaluating the rate of BRAFV600E mutations among patients who had been diagnosed with primary papillary thyroid carcinoma (PTC) and PCM showed that patients with either PCM or PTC were at an increased risk of developing the other as a second primary malignant neoplasm. Furthermore, the authors noted that samples from patients suffering from both malignancies exhibited a higher rate of incidence of the BRAFV600E mutation, compared with patients not suffering from both malignancies. These studies support the hypothesis that the pathogenesis of these 2 malignancies might share a conserved molecular pattern associated with dysregulation of the BRAF protein. One mechanism through which BRAF might contribute to PCM and thyroid carcinoma progression is through induction of epithelial-mesenchymal transition (EMT). Specifically, the Snail/E-cadherin axis has been demonstrated as a pathway dysregulated by BRAF, leading to EMT in both malignancies. Our analysis focuses on the results of these recent investigations, and through a review of select molecules relevant to EMT, looks to provide a context by which to better understand the relevance and role of stromal-parenchymal signaling and the BRAF mutation in the pathogenesis of PTC and PCM.

Sentinel Lymph Node Biopsy in Thin Cutaneous Melanoma: A Systematic Review and Meta-Analysis

BACKGROUND

Most patients with melanoma have a thin (≤1.00 mm) lesion. There is uncertainty as to which patients with thin melanoma should undergo sentinel lymph node (SN) biopsy. We sought to quantify the proportion of SN metastases in patients with thin melanoma and to determine the pooled effect of high-risk features of the primary lesion on SN positivity.

METHODS

Published literature between 1980 and 2015 was searched and critically appraised. Primary outcome was the proportion of SN metastases in patients with thin cutaneous melanoma. Secondary outcomes included the effect of high-risk pathological features of the primary lesion on the proportion of SN metastases. Summary measures were estimated by Mantel-Haenszel method using random effects meta-analyses.

RESULTS

Sixty studies (10,928 patients) met the criteria for inclusion. Pooled SN positivity was 4.5 % [95 % confidence interval (CI) 3.8-5.2 %]. Predictors of a positive SN were: thickness ≥0.75 mm [adjusted odds ratio (AOR) 1.90 (95 % CI 1.08-3.34); with a likelihood of SN metastases of 8.8 % (95 % CI 6.4-11.2 %)]; Clark level IV/V [AOR 2.24 (95 % CI 1.23-4.08); with a likelihood of 7.3 % (95 % CI 6.2-8.4 %)]; ≥1 mitoses/mm² [AOR 6.64 (95 % CI 2.77-15.88); pooled likelihood 8.8 % (95 % CI 6.2-11.4 %)]; and the presence of microsatellites [unadjusted OR 6.94 (95 % CI 2.13-22.60); likelihood 26.6 % (95 % CI 4.3-48.9 %)].

CONCLUSIONS

The pooled proportion of SN metastases in thin melanoma is 4.5 %. Thickness ≥0.75 mm, Clark level IV/V, mitoses, and microsatellites significantly increased the odds of SN positivity and should prompt strong consideration of SN biopsy.

Differential diagnosis of heavily pigmented melanocytic lesions: challenges and diagnostic approach

The differential diagnosis of heavily pigmented melanocytic neoplasms includes melanoma (especially animal type), melanosis of partially or completely regressed melanoma, blue naevus (BN), pigmented Spitzoid lesions, recurrent naevus, combined naevus, pigmented spindle cell naevus, epithelioid blue naevus of the Carney complex/pigmented epithelioid melanocytoma, deep penetrating naevus, hyperpigmented scar after surgery of melanoma in which there are also melanophages and hyperpigmentation due to the minocycline, a tattoo or a hyperpigmented scar. Pathologists face challenges when evaluating a pigmented lesion, especially in a small superficial biopsy, because it is difficult to access important histopathological features to differentiate benign versus malignant melanocytic lesions. The histological features that favour a diagnosis of melanoma include dimension (>6 mm), asymmetry, poor circumscription, irregular confluent nests, confluent lentiginous junctional melanocytic proliferation, lack of maturation with descent in the dermis, suprabasal pagetoid melanocytes, asymmetrical distribution of melanin pigment, cytological atypia, dermal mitotic figures, asymmetrical dermal lymphocytic infiltrate and necrosis.