Lymphatic invasion predicts aggressive behavior in melanocytic tumors of uncertain malignant potential (MELTUMP)

Ambiguous melanocytic lesions: A retrospective cohort study of incidence and outcome of melanocytic tumor of uncertain malignant potential (MELTUMP) and superficial atypical melanocytic proliferation of uncertain significance (SAMPUS) in the Netherlands

BACKGROUND

Melanocytic tumor of uncertain malignant potential (MELTUMP) and superficial atypical melanocytic proliferation of uncertain significance (SAMPUS) are descriptive and provisional terms for melanocytic tumors with ambiguous histopathological features that are not easily classified as either benign or malignant.

OBJECTIVE

To investigate the incidence and clinical outcome of MELTUMP and SAMPUS in the Netherlands.

METHODS

In this retrospective cohort study, we reviewed all diagnoses of MELTUMP and SAMPUS from the Dutch Nationwide Pathology Databank from 1991 to October 1, 2021. Clinical outcome was studied for cases diagnosed until October 1, 2018.

RESULTS

A total of 1685 MELTUMP and 1957 SAMPUS were identified with an annual incidence of 150 to 300 cases. Metastatic behavior was seen in 0.7% of all initially diagnosed MELTUMP. All SAMPUS remained free of metastases.

LIMITATIONS

Reassessment of pathology slides and confirmation of clonality between primary and metastatic lesions remained outside the scope of this study.

CONCLUSION

Despite the 'uncertainty' in the nomenclature, our results demonstrate a low malignant potential for MELTUMP and no malignant potential for SAMPUS. We emphasize the importance of consultation for ambiguous melanocytic lesions and to limit the MELTUMP/SAMPUS terminology to legitimately uncertain or unclassifiable cases.

Molecular characterization of biphenotypic epithelioid and plexiform melanoma with deep penetrating nevus-like features

Tumor heterogeneity is a relevant hallmark of melanoma due to the high mutation burden and immunogenicity commonly encountered. Heterogeneity at the histologic level frequently corresponds to heterogeneity at the molecular level. A better understanding of this feature of malignancy can help refine the development of predictive biomarkers and to define more effective targeted therapies. Here, we describe a case of melanoma displaying a dual phenotype: a DPN-like/plexiform portion in conjunction with a conventional epithelioid morphology. Molecular studies revealed shared BRAF and PTEN mutations in both components but a CTNNB1 mutation was exclusively found in the DPN-like area of the tumor, consistent with the distinct morphology observed. There was considerable heterogeneity in sequence variants identified in the two regions. Gene expression analysis highlighted differentially regulated genes between the two histologies, including a relevant cluster of genes in the receptor tyrosine kinase (RTK) family and related signaling pathways upregulated in the DPN-like/plexiform area.

Interpretation of the Complex Melanoma Pathology Report

An ambiguous pathologic report can present a clinical dilemma to the treating surgeon. We describe lesions ranging from the potentially benign to the likely malignant. Correctly identifying features associated with higher-risk lesions has proven challenging given the overall good prognosis and low rate of events. An appropriate treatment plan generally requires discussion between the surgeon and an experienced dermatopathologist. When clinically indicated, additional testing may be used to further support or refute a diagnosis of melanoma. The indications for these techniques, the data to support their use, and the strengths and weakness of each are reviewed.

Hyperspectral and multispectral imaging in digital and computational pathology: a systematic review [Invited]

Hyperspectral imaging (HSI) and multispectral imaging (MSI) technologies have the potential to transform the fields of digital and computational pathology. Traditional digitized histopathological slides are imaged with RGB imaging. Utilizing HSI/MSI, spectral information across wavelengths within and beyond the visual range can complement spatial information for the creation of computer-aided diagnostic tools for both stained and unstained histological specimens. In this systematic review, we summarize the methods and uses of HSI/MSI for staining and color correction, immunohistochemistry, autofluorescence, and histopathological diagnostic research. Studies include hematology, breast cancer, head and neck cancer, skin cancer, and diseases of central nervous, gastrointestinal, and genitourinary systems. The use of HSI/MSI suggest an improvement in the detection of diseases and clinical practice compared with traditional RGB analysis, and brings new opportunities in histological analysis of samples, such as digital staining or alleviating the inter-laboratory variability of digitized samples. Nevertheless, the number of studies in this field is currently limited, and more research is needed to confirm the advantages of this technology compared to conventional imagery.

Deep Penetrating Nevus and Borderline-Deep Penetrating Nevus: A Literature Review

Deep penetrating nevi (DPN) are rare melanocytic nevi, which can exhibit atypical histological features hampering the differentiation from malignant melanoma. DPN are considered benign melanocytic lesions, but rare spread to lymph nodes and unfavorable clinical outcomes associated with borderline/atypical DPN (B-DPN) has been reported. Since no guidelines are available for DPN and B-DPN, we aimed to review the literature on DPN and B-DPN to assess the management and prognosis. We screened 3,513 references from EMBASE, Scopus and Medline databases, and included 15 studies with a total of 355 DPN patients and 48 B-DPN patients. Therapeutic interventions ranged from simple excision to wide excisions and sentinel lymph node biopsy (SLNB), with block lymph node dissection in some positive SLNB cases. Follow-up periods ranged from 3 months to 23 years during which a total of five recurrences, two in DPN and three in B-DPN group, and three metastases, in B-DPN group, were reported. While some of the included studies comprised clinical and histopathological correlation, few included genetic assessment. The present review highlights the need for prospective cohort studies applying composite measures to identify effective regimens of diagnostic workup and treatment in DPN and B-DPN.

Stromal inflammatory cells are associated with poorer prognosis in primary cutaneous melanoma

We observed that non-tumor-infiltrating inflammatory cells are often present in the stroma of melanoma. The role of these stromal inflammatory cells (SIC) in cancer has not been studied. We evaluated the prognostic significance of SIC in 299 patients with vertical growth phase primary melanomas with at least 10 years of clinical follow-up. Lymphatic density and lymphatic invasion in the areas with SIC was quantified. The prognostic significance of these factors was evaluated using univariable and multivariable Cox models for melanoma-specific death and the time to first recurrence. Of the 299 melanomas, 161 exhibited areas with SIC. Percentages of vertical growth phase tumor-infiltrating lymphocytes and radial growth phase regression were significantly higher in cases with SIC compared to those without SIC (P = .005); lymphatic invasion was also detected more frequently in cases with SIC (P = .001). Lymphatic density in SIC areas was higher than that in other areas of the melanomas. Patients with SIC had poorer clinical outcome. Vascular endothelial growth factor-C (VEGFC) staining in a subset of these melanoma patients showed that VEGFC expression in the stromal macrophages was associated with lymphatic invasion in SIC areas. In conclusion, SIC in melanoma is associated with poorer prognosis, and the prognostic effect is partially mediated through induction of lymphangiogenesis with increased lymphatic invasion.

Atypical Melanocytic Proliferations: A Review of the Literature

BACKGROUND

Ambiguous histopathologic diagnoses represent a challenge for clinicians because of a lack of definitive diagnosis and related uncertainty about management.

OBJECTIVE

To review the literature on atypical melanocytic proliferations and detail synonymous terms, epidemiology, diagnostic work-up, histopathology, treatment, and prognosis.

METHODS

Databases from PubMed and Web of Science were searched for articles related to atypical melanocytic proliferations.

RESULTS

Intraepidermal melanocytic proliferations with features worrisome for possible melanoma in situ (MIS) are generally excised as for MIS. Reported rates of upstaging of such cases to invasive melanoma on review of the excision are very low. Because invasion, lymph node spread, and metastasis can occur in atypical melanocytic lesions with a thick intradermal component, these are often treated as for malignant melanoma.

CONCLUSION

Because the diagnosis dictates treatment, it is incumbent to establish a diagnosis as definitive as possible, obtaining second or third opinions and using ancillary studies when appropriate. When the diagnosis remains uncertain, it is difficult to provide guidelines for treatment. Clinical care decisions for patients with an uncertain diagnosis are best done on a case-by-case basis weighing probabilities of adverse outcomes against potential benefits and risks from various treatment options.

Lymphatic invasion predicts sentinel lymph node metastasis and adverse outcome in primary cutaneous melanoma

BACKGROUND

Sentinel lymph node (SLN) metastasis is a powerful predictor of survival in primary cutaneous melanoma. Lymphatic invasion (LI) may correlate with increased risk of SLN metastasis. Intralymphatic metastases, often difficult to detect on hematoxylin and eosin (H&E) stained sections, are readily identified with dual immunohistochemistry for melanocytic and lymphatic markers.

METHODS

We used dual S100/D240 immunohistochemistry to detect LI in 125 melanomas from patients who underwent SLN biopsy and correlated LI with melanoma staging parameters and disease status.

RESULTS

Dual immunohistochemistry allowed for the identification of LI in 33 cases (26%), compared to only 2% on H&E stained sections. Melanomas with LI showed greater thickness, higher mitotic rate and more frequent ulceration. Eleven of 33 cases with LI (33%) and 10 of 92 cases without LI (11%) were associated with a positive SLN (P = .006). More patients without LI were disease-free at last follow-up (80%) than patients with LI (50%; P = .002); LI was significantly associated with decreased progression-free survival.

CONCLUSION

The detection of LI is improved by dual immunohistochemistry and predicts SLN metastasis. The presence of LI may impact therapeutic planning in melanoma, such as the decision to perform a SLN biopsy.

Lymphatic invasion and angiotropism in primary cutaneous melanoma

Access of melanoma cells to the cutaneous vasculature either via lymphatic invasion or angiotropism is a proposed mechanism for metastasis. Lymphatic invasion is believed to be a mechanism by which melanoma cells can disseminate to regional lymph nodes and to distant sites and may be predictive of adverse outcomes. Although it can be detected on hematoxylin- and eosin-stained sections, sensitivity is markedly improved by immunohistochemistry for lymphatic endothelial cells. Multiple studies have reported a significant association between the presence of lymphatic invasion and sentinel lymph node metastasis and survival. More recently, extravascular migratory metastasis has been suggested as another means by which melanoma cells can spread. Angiotropism, the histopathologic correlate of extravascular migratory metastasis, has also been associated with melanoma metastasis and disease recurrence. Although lymphatic invasion and angiotropism are not currently part of routine melanoma reporting, the detection of these attributes using ancillary immunohistochemical stains may be useful in therapeutic planning for patients with melanoma.

Variation among pathologists' treatment suggestions for melanocytic lesions: A survey of pathologists

BACKGROUND

The extent of variability in treatment suggestions for melanocytic lesions made by pathologists is unknown.

OBJECTIVE

We investigated how often pathologists rendered suggestions, reasons for providing suggestions, and concordance with national guidelines.

METHODS

We conducted a cross-sectional survey of pathologists. Data included physician characteristics, experience, and treatment recommendation practices.

RESULTS

Of 301 pathologists, 207 (69%) from 10 states (California, Connecticut, Hawaii, Iowa, Kentucky, Louisiana, New Jersey, New Mexico, Utah, and Washington) enrolled. In all, 15% and 7% reported never and always including suggestions, respectively. Reasons for offering suggestions included improved care (79%), clarification (68%), and legal liability (39%). Reasons for not offering suggestions included referring physician preference (48%), lack of clinical information (44%), and expertise (29%). Training and caseload were associated with offering suggestions (P < .05). Physician suggestions were most consistent for mild/moderate dysplastic nevi and melanoma. For melanoma in situ, 18 (9%) and 32 (15%) pathologists made suggestions that undertreated or overtreated lesions based on National Comprehensive Cancer Network (NCCN) guidelines, respectively. For invasive melanoma, 14 (7%) pathologists made treatment suggestions that undertreated lesions based on NCCN guidelines.

LIMITATIONS

Treatment suggestions were self-reported.

CONCLUSIONS

Pathologists made recommendations ranging in consistency. These findings may inform efforts to reduce treatment variability and optimize patterns of care delivery for patients.

Multiple Gastrointestinal Polyps in Patients Treated with BRAF Inhibitors

PURPOSE

BRAF inhibitors (BRAFi) extend survival in BRAF-mutant melanoma but can promote the growth of Ras-mutant neoplasms. This study determined if gastrointestinal polyps found in BRAFi-treated patients harbored Ras mutations.

EXPERIMENTAL DESIGN

Colonic and gastric polyps were identified and resected from BRAFi-treated melanoma patients. Next-generation sequencing (NGS) was performed on polyps. The ability of BRAFi to promote polyp formation was functionally characterized in Apc Min(+/-) mice. MAPK and β-catenin pathway activity was assessed by immunohistochemistry in mouse and human polyps.

RESULTS

Fourteen patients treated with BRAFi underwent endoscopy to assess for polyps. Seven out of 7 patients >40 years of age and treated for >2 years were found to have colonic tubular adenomas with 4 out of the 7 patients having 5 or more polyps. One patient presented with bleeding from hyperplastic gastric polyps that recurred 6 months after BRAFi rechallenge. NGS performed on polyps found no mutations in MAPK pathway genes, but found APC mutations in all tubular adenomas. A significant increase in the number of polyps was observed in BRAFi-treated compared with control-treated Apc Min(+/-) mice (20.8 ± 9.2 vs 12.8 ± 0.1; P = 0.016). No polyps were observed in BRAFi-treated wild-type mice.

CONCLUSIONS

BRAFi may increase the risk of developing hyperplastic gastric polyps and colonic adenomatous polyps. Due to the risk of gastrointestinal bleeding and the possibility of malignant transformation, further studies are needed to determine whether or not endoscopic surveillance should be recommended for patients treated with BRAFi.

Melanocytic tumour with unknown malignant potential--a Danish study of 67 patients

The aim of our single clinical centre study was to evaluate the risk of local metastases, lymph node metastases and distant metastases in patients diagnosed with melanocytic tumour with unknown malignant potential (MELTUMP). Furthermore, we evaluated several histologic tumour characteristics as potential predictive factors. From 1 January 1999 to 30 June 2011, a total of 67 consecutive patients were diagnosed with MELTUMP in our hospital. In this study, all the pathology slides were reviewed by the same independent expert dermatopathologist. All data were retrieved from patient charts. Four patients (6%) had regional nodal dissemination at the time of the diagnosis. Furthermore, one patient (1%) developed regional spread during follow-up and another patient (1%) died from distant metastases 1 year after diagnosis. We found no predictive factors with regard to histologic tumour characteristics. Our study confirms the low malignant potential of MELTUMP. We found a low risk of nodal metastasis and mortality from distant metastasis during follow-up. We recommend that all patients diagnosed with MELTUMP should be treated according to the guidelines for invasive melanoma.

Multispectral Imaging

The field of anatomic pathology has changed significantly over the last decades and, as a result of the technological developments in molecular pathology and genetics, has had increasing pressures put on it to become quantitative and to provide more information about protein expression on a cellular level in tissue sections. Multispectral imaging (MSI) has a long history as an advanced imaging modality and has been used for over a decade now in pathology to improve quantitative accuracy, enable the analysis of multicolor immunohistochemistry, and drastically reduce the impact of contrast-robbing tissue autofluorescence common in formalin-fixed, paraffin-embedded tissues. When combined with advanced software for the automated segmentation of different tissue morphologies (eg, tumor vs stroma) and cellular and subcellular segmentation, MSI can enable the per-cell quantitation of many markers simultaneously. This article covers the role that MSI has played in anatomic pathology in the analysis of formalin-fixed, paraffin-embedded tissue sections, discusses the technological aspects of why MSI has been adopted, and provides a review of the literature of the application of MSI in anatomic pathology.