Clinical significance of BRAF V600E mutational status in capsular nevi of sentinel lymph nodes in patients with primary cutaneous melanoma

Sentinel lymph node assessment in melanoma: current state and future directions

Assessment of sentinel lymph node status is an important step in the evaluation of patients with melanoma for both prognosis and therapeutic management. Pathologists have an important role in this evaluation. The methodologies have varied over time, from the evaluation of dimensions of metastatic burden to determination of the location of the tumour deposits within the lymph node to precise cell counting. However, no single method of sentinel lymph node tumour burden measurement can currently be used as a sole independent predictor of prognosis. The management approach to sentinel lymph node-positive patients has also evolved over time, with a more conservative approach recently recognised for selected cases. This review gives an overview of past and current status in the field with a glimpse into future directions based on prior experiences and clinical trials.

HMB45/PRAME, a Novel Double Staining for the Diagnosis of Melanocytic Neoplasms: Technical Aspects, Results, and Comparison With Other Commercially Available Staining (PRAME and Melan A/PRAME)

PRAME (PReferentially expressed Antigen in MElanoma) is a tumor-associated antigen that was recently found to be expressed by malignant melanocytic lesions but not by benign ones, thus resulting useful in this diagnostic field. PRAME could also be expressed by some normal tissues and nonmelanocytic tumors, suggesting as caution should be adopted to use PRAME as a "pan-melanoma" marker for the differential diagnosis with other malignant tumors. Until now, PRAME expression was exclusively investigated through single staining with a monoclonal antibody targeting PRAME and with double staining for Melan A/PRAME found to be useful in specific diagnostic sets. Herein, we studied the expression of PRAME in 40 melanocytic lesions and 23 nonmelanocytic ones using PRAME, Melan A/PRAME, and novel double staining for HMB45/PRAME. Although our results need to be validated, they support the adoption of HMB45/PRAME, alone or in combination with PRAME and Melan A/PRAME, as a helpful marker in the diagnosis of melanocytic neoplasms with a high concordance rate between primary melanoma and corresponding metastases.

Comparison of mutation profiles in primary melanomas and corresponding nodal naevi using next-generation sequencing

BACKGROUND

Nodal naevi (NN) represent aggregates of melanocytes within peripheral lymph nodes. NN are relatively often found in patients with malignant melanoma (MM), and may mimic metastatic disease.

AIM

To study mutation profiles in MM and NN to find out whether NN descend from a primary MM.

METHODS

Next-generation sequencing was performed on formalin-fixed paraffin-embedded tissue of 26 pairs of primary MM and corresponding NN detected by sentinel lymph node biopsy, and 29 MM-characteristic genes were investigated.

RESULTS

In this study, 90% of mutations were detected exclusively in either MM or NN, but not both, in the same patient; the percentage of identical NN and MM mutations in the same individual was only 10%. The most frequently discovered shared mutations were a C>G substitution in the CDKN2A gene and in-frame deletion in ARID1A. Oncogenic driver mutations were frequently observed in MM but only rarely in NN. About three-quarters of mutations in both MM and NN were characterized by C>T or G>A substitutions. The detected rate of ultraviolet (UV)-related C>T base changes was comparably high in both primary MM (35%) and NN (32%).

CONCLUSIONS

Based on our data, it seems that NN descend from previously UV-exposed BRAF wildtype cutaneous melanocytes, rather than from primary MM or arrested progenitor cells.

Three Types of Nodal Melanocytic Nevi in Sentinel Lymph Nodes of Patients With Melanoma: Pitfalls, Immunohistochemistry, and a Review of the Literature

The presence or absence of metastasis in sentinel lymph nodes often drives melanoma staging, prognosis, and treatment. However, distinguishing between metastatic melanoma cells and clusters of benign melanocytic nevus cells is not always straightforward. When morphologic hematoxylin and eosin interpretation alone is not sufficient, additional hematoxylin and eosin sections and immunohistochemical (IHC) studies may be beneficial. This review and small cases series of 3 diagnostically challenging melanocytic sentinel lymph node cases highlights the IHC approach to evaluate intraparenchymal nodal melanocytic nevi, coexistent metastatic melanoma with adjacent melanocytic nevi cells, and nodal blue nevi. In challenging cases, cytological morphology of the melanocytes, location within the lymph node, and IHC studies may assist in diagnosis. If these tools yield conflicting results, expert opinion is recommended.

Phosphodiesterase Type 5 Inhibitors and Risk of Skin Cancers in Men: A Meta-Analysis and Trial Sequential Analysis Involving 7,479,852 Subjects

Purpose

We conducted a systematic review and meta-analysis to quantify the association between phosphodiesterase type 5 inhibitors (PDE5Is) use and skin cancers and we also examined whether down-expression of the PDE5A gene was related to worse prognosis for malignant melanoma (MM) patients.

Materials and Methods

The PubMed, Cochrane Library, Web of Science, EMBASE, and ClinicalTrails.gov databases were searched. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the association between PDE5Is use and risk of skin cancers. Cumulative meta-analysis and trial sequential analysis (TSA) were also conducted. Survival outcomes were analyzed online.

Results

After pooling all 8 eligible studies comprising 7,479,852 subjects, we found that PDE5Is use was significantly associated with slightly increased risk of developing MM (OR: 1.13, 95% CI: 1.05 to 1.21, I²=67.1%), basal cell carcinoma (OR: 1.16, 95% CI: 1.13 to 1.19, I²=49.6%), and squamous cell carcinoma (OR: 1.07, 95% CI: 1.01 to 1.13, I²=0.0%). Totally, PDE5Is increased the risk of developing skin cancers (OR: 1.13, 95% CI: 1.09 to 1.17, I²=70.8%). TSA results showed that the sample size was enough to reach a positive conclusion.

Conclusions

The use of PDE5Is may be slightly associated with increased risk of developing skin cancers. There should be a balance between drug benefits and potential safety issues. However, the pooled results should be considered tentative until confounding factors such as sun exposure and lifestyle are well-controlled in further studies.

Clinical significance of SLN benign capsular nevi in patients with melanoma

BACKGROUND

Benign capsular nevi (BCN) are not infrequent in sentinel lymph nodes (SLN) of patients with melanoma. Their prognostic significance is unknown and the literature is limited. This study evaluated the clinical significance of incidentally found BCN in these patients.

METHODS

A multi-institutional retrospective review of patients undergoing SLN biopsy for cutaneous melanoma between 2000 and 2016. Patients were divided into the following groups: (a) negative SLN and no BCN, (b) negative SLN and presence of BCN, (c) positive SLN seen only on immunohistochemistry (IHC), and (d) positive SLN via hematoxylin and eosin (H&E). Outcomes measured were overall survival and any recurrence.

RESULTS

A total of 1253 patients were identified (group 1 = 978, group 2 = 56, group 3 = 32, and group 4 = 187). Fifty-seven percent were male and the mean age was 59.3 years. BCN was identified in 77 patients (6.2%), of which the majority was in the node-negative group (72%). Multivariable analysis showed that BCN was associated with lower recurrence rates, though not statistically significant (hazard ratio [HR] = 0.5; P = .06). IHC- and H&E-positive SLNs were associated with a higher risk of recurrence (HR = 2.4; P = .02 and 2.0, P < .0001, respectively).

CONCLUSION

Patients with BCN and negative SLN had lower recurrence rates than patients with negative SLN and no BCN. Our data suggest a possible protective effect against recurrence.

Metastases risk in thin cutaneous melanoma: prognostic value of clinical-pathologic characteristics and mutation profile

Background

A high percentage of patients with thin melanoma (TM), defined as lesions with Breslow thickness ≤1 mm, presents excellent long-term survival, however, some patients develop metastases. Existing prognostic factors cannot reliably differentiate TM patients at risk for metastases.

Objective

We aimed at characterizing the clinical-pathologic and mutation profile of metastatic and not-metastatic TM in order to distinguish lesions at risk of metastases.

Methods

Clinical-pathologic characteristics were recorded for the TM cases analyzed. We used a Next Generation Sequencing (NGS) multi-gene panel to characterize TM for multiple somatic mutations.

Results

A statistically significant association emerged between the presence of metastases and Breslow thickness ≥0.6 mm (p=0.003). None of TM with lymph-node involvement had Breslow thickness <0.6 mm. Somatic mutations were identified in 19 of 21 TM analyzed (90.5%). No mutations were observed in two not-metastatic cases with the lowest Breslow thickness (≤0.4 mm), whereas mutations in more than one gene were detected in one metastatic case with the highest Breslow thickness (1.00 mm).

Conclusion

Our study indicates Breslow thickness ≥0.6 mm as a valid prognostic factor to distinguish TM at risk for metastases.

Use of phosphodiesterase type 5 inhibitors and risk of melanoma: a meta-analysis of observational studies

Background

Phosphodiesterase type 5 inhibitor (PE5i) administration may stimulate the proliferation and survival of melanocytes. However, discrepancies remain regarding the association between PDE5i use and melanoma risk in observational studies in humans.

Aim

To evaluate the association between PDE5i use and melanoma in a meta-analysis.

Materials and methods

Studies were identified by searching the PubMed and Embase databases. A random-effects model was applied to synthesize the data. A stratified study was performed to evaluate the influence of study characteristics on outcomes.

Results

Four prospective cohort studies and three case–control studies with 1,534,615 male participants and 16,053 melanoma cases were incorporated. Patients who received a PDE5i had a significantly increased risk for melanoma (adjusted risk ratio [RR] =1.12, 95% CI =1.03–1.33, P=0.008) with moderate heterogeneity (I²=54%). Cohort studies (adjusted RR =1.22, 95% CI =1.02–1.46, P=0.03) largely contributed to this result rather than case–control studies. Subsequent stratified analyses revealed that sildenafil was associated with an increased risk of melanoma (adjusted RR =1.26, 95% CI =1.07–1.50, P=0.007), but tadalafil and vardenafil were not. Also, PDE5i use was associated with a significantly increased risk of in situ melanoma (adjusted RR =1.31, 95% CI =1.01–1.69, P=0.04), but not of localized or nonlocalized melanoma.

Conclusion

PDE5i use may be associated with a significantly increased risk for melanoma in men. However, further research is needed to determine whether the association is causative.