Intraepidermal epidermotropic metastatic melanoma: a clinical and histopathological mimicker of melanoma in situ occurring in multiplicity

Metastasis to hypopharynx from epidermotropic metastatic malignant melanoma

Previous reports proposed the concept and criteria of epidermotropic metastatic malignant melanoma (EMMM): (a) dermal involvement equal to or broader than the epidermal involvement, (b) atypical melanocytes within the dermis, (c) thinning of the epidermis, (d) widening of the papillary dermis with an epithelial collarette, and (e) vascular invasion of atypical melanocytes. However, it remains unclear whether EMMM also involves the mucosal epithelium. In this case, the patient was diagnosed with EMMM based on the histopathological findings of the patient's multiple skin lesions and clinical course. The patient also developed metastasis to the hypopharynx. Although histopathological findings of the lesion suggested the possibility of melanoma in situ, as the lesion included atypical melanocytes in the mucosal epithelium, the clinical course supported the diagnosis of hypopharyngeal metastasis from EMMM. This case suggests that EMMM may have epitheliotropic features not only in the skin but also in the mucosa.

Metastasis to the stomach: a systematic review

Background: This study reviews the literature on gastric metastases (GM) in terms of diagnosis, treatment, and outcomes. The goal of this study was to provide clinicians with a reliable and beneficial source to understand gastric metastases arising from various primary tumors and to present the growing literature in an easily accessible form. Methods: Articles published in English language from implementation of MEDLINE and Cochrane databases until May 2022 were considered for the systematic review. Articles other than English language, letters to the editor, posters, and clinical images were excluded. Hematogenous and lymphogenic metastases were included whereas direct tumoral invasion and seeding were excluded. Articles and abstracts were analyzed and last selection was done after cross-referencing and by use of defined eligibility criteria. Results: In total 1,521 publications were identified and 170 articles were finally included totaling 186 patients with GM. The median age of patients was 62 years. Gynecologic cancer was the most common cancer type causing GM (67 patients), followed by lung cancer (33 patients), renal cancer (20 patients), and melanoma (19 patients). One of the main treatment methods performed for metastasis was resection surgery (n=62), sometimes combined with chemotherapy (ChT) or immunotherapy. ChT was the other most used treatment method (n=78). Also, immunotherapy was amongst the most preferred treatment options after surgery and ChT (n=10). Conclusions: As 172 case reports were screened in the systematic review from different journals, heterogeneity was inevitable. Some articles missed important information such as complete follow-up or clinical information. Moreover, since all of the included articles were case reports quality assessment could not be performed. Among 172 case reports reviewed, resection surgery was performed the most and was sometimes combined with ChT and immunotherapy. Further research about what type of treatment has the best outcomes for patients with gastric metastases is needed.

Metastatic Melanoma to a Neurofibroma

ABSTRACT

We present an extraordinary case of metastatic cutaneous melanoma to a pre-existing neurofibroma in a 75-year-old man with a history of primary invasive melanoma in an anatomically close vicinity. Histological examination of the metastatic melanoma showed a well-circumscribed intradermal nodule of frankly malignant epithelioid melanocytes without an intraepidermal component, surrounded and sharply demarcated from a diffuse spindle cell proliferation with morphological features of a neurofibroma. The spindle cell component showed bland cytologic features, with no mitotic activity or lymphocytic inflammation and no features of malignancy. By immunohistochemistry, both components expressed S100, while HMB45 positivity and complete loss of p16 were only observed in the epithelioid cells. The morphologically distinct areas were analyzed by fluorescent in situ hybridization, which demonstrated an abnormal profile (gain of RREB1 and homozygous loss of CDKN2A) in the epithelioid nodule; however, no abnormalities were detected in the spindle cell component. Next-generation sequencing showed somatic NRAS and PTEN mutations in the melanoma cells only. The overall molecular findings supported the immunomorphological diagnosis of metastatic melanoma within a neurofibroma over the potential differential diagnosis of melanoma with a neurofibroma-like spindle/desmoplastic component.

The 2018 World Health Organization Classification of Cutaneous, Mucosal, and Uveal Melanoma: Detailed Analysis of 9 Distinct Subtypes Defined by Their Evolutionary Pathway

CONTEXT.—

There have been major advances in the understanding of melanoma since the last revision of the World Health Organization (WHO) classification in 2006.

OBJECTIVE.—

To discuss development of the 9 distinct types of melanoma and distinguishing them by their epidemiology, clinical and histologic morphology, and genomic characteristics. Each melanoma subtype is placed at the end of an evolutionary pathway that is rooted in its respective precursor, wherever appropriate and feasible, based on currently known data. Each precursor has a variable risk of progression culminating in its fully evolved, invasive melanoma.

DATA SOURCES.—

This review is based on the "Melanocytic Tumours" section of the 4th edition of the WHO Classification of Skin Tumours, published in 2018.

CONCLUSIONS.—

Melanomas were divided into those etiologically related to sun exposure and those that are not, as determined by their mutational signatures, anatomic site, and epidemiology. Melanomas on the sun-exposed skin were further divided by the histopathologic degree of cumulative solar damage (CSD) of the surrounding skin, into low and high CSD, on the basis of degree of associated solar elastosis. Low-CSD melanomas include superficial spreading melanomas and high-CSD melanomas incorporate lentigo maligna and desmoplastic melanomas. The "nonsolar" category includes acral melanomas, some melanomas in congenital nevi, melanomas in blue nevi, Spitz melanomas, mucosal melanomas, and uveal melanomas. The general term melanocytoma is proposed to encompass "intermediate" tumors that have an increased (though still low) probability of disease progression to melanoma.

Dynamic Evolution of Clonal Composition and Neoantigen Landscape in Recurrent Metastatic Melanoma with a Rare Combination of Driver Mutations

In melanoma, initiating oncogenic mutations in BRAF or NRAS are detected in premalignant lesions that accumulate additional mutations and genomic instability as the tumor evolves to the metastatic state. Here we investigate evolution of clonal composition and neoantigen landscape in an atypical melanoma displaying recurrent cutaneous lesions over a 6-year period without development of extracutaneous metastases. Whole exome sequencing of four cutaneous lesions taken during the 6-year period identified a collection of single nucleotide variants and small insertions and deletions shared among all tumors, along with progressive selection of subclones displaying fewer single nucleotide variants. Later tumors also displayed lower neoantigen burden compared to early tumors, suggesting that clonal evolution was driven, at least in part, by counter selection of subclones with high neoantigen burdens. Among the selected mutations are a missense mutation in MAP2K1 (F53Y) and an inversion on chromosome 7 generating a AKAP9-BRAF fusion. The mutant proteins cooperatively activate the MAPK signaling pathway confirming they are potential driver mutations of this tumor. We therefore describe the long-term genetic evolution of cutaneous metastatic melanoma characterized by an unexpected phenotypic stability and neoantigen-driven clonal selection.

Morphological classification of melanoma metastasis with reflectance confocal microscopy

BACKGROUND

Cutaneous malignant melanoma metastases differential diagnosis is challenging, as clinical and dermoscopic features can simulate primary melanoma or other benign or malignant skin neoplasms, and in-vivo reflectance confocal microscopy could assist. Our aim was to identify specific reflectance confocal microscopy features for cutaneous malignant melanoma metastases, and epidermal and dermal involvement.

METHODS

A retrospective, multicentre observational study of lesions with proven cutaneous malignant melanoma metastases diagnosis between January 2005 and December 2016. Lesions were retrospectively assessed according to morphological features observed at reflectance confocal microscopy. Potential homogeneous subgroups of epidermal or dermal involvement were investigated with cluster analysis.

RESULTS

Cutaneous malignant melanoma metastases (51 lesions in 29 patients) exhibited different frequencies of features according to metastasis dermoscopy patterns. Lesions classified at dermoscopy with nevus-like globular and non-globular patterns were more likely to be epidermotropic, showing characteristics of epidermal and dermal involvement at reflectance confocal microscopy. Other dermoscopy pattern classifications were more likely to be dermotropic, showing characteristics od dermal involvement at reflectance confocal microscopy. Distinguishing features at reflectance confocal microscopy included irregular (78%) and altered (63%) epidermis, pagetoid infiltration (51%), disarranged junctional architecture (63%), non-edged papillae (76%), dense and sparse, and cerebriform nests in the upper dermis (74%), and vascularity (51%). Cluster analysis identified three groups, which were retrospectively correlated with histopathological diagnoses of dermotropic and epidermotropic diagnoses (P < 0.001). The third cluster represents lesions with deep dermis morphological changes, which were too deep for evaluation with reflectance confocal microscopy.

CONCLUSIONS

Specific reflectance confocal microscopy features of cutaneous malignant melanoma metastases for correct diagnosis, and subtype diagnosis, seem achievable in most cases where morphological alterations are located above the deep dermis.

Comprehensive histopathological comparison of epidermotropic/dermal metastatic melanoma and primary nodular melanoma

AIMS

Metastatic melanoma involving the epidermis and/or upper dermis may show significant histological overlap with primary cutaneous melanoma, especially the nodular subtype. Proper histopathological classification is crucial to appropriate staging and management, but is often challenging. The aim of this study was to identify helpful histopathological features for differentiating epidermotropic/dermal metastatic melanoma (EDMM) and primary nodular melanoma (PNM).

METHODS AND RESULTS

A cohort of EDMMs (n = 74) and PNMs (n = 75) was retrospectively reviewed for various histopathological features, and the data were compared between groups by the use of univariate analysis. Features significantly associated with EDMM included a tumour size of <2 mm, an absence of tumour-infiltrating lymphocytes and plasma cells, monomorphism, and involvement of adnexal epithelium. Features associated with PNM included a polypoid (exophytic) configuration, prominent tumour-infiltrating plasma cells (TIPs), a tumour size of >10 mm, ulceration, epidermal collarettes, a higher mitotic rate, necrosis, multiple phenotypes, significant pleomorphism, and lichenoid inflammation. In multivariate analysis, a logistic regression model including large tumour size, ulceration, prominent TIPs, lichenoid inflammation and epidermal collarettes was highly predictive of PNM. Six (8%) EDMMs from three patients showed an 'epidermal-only' or 'epidermal-predominant' pattern closely simulating in-situ or microinvasive melanoma. Two of these cases were tested by fluorescence in-situ hybridisation, which confirmed clonal relationships with their corresponding primary melanomas.

CONCLUSIONS

This is the first comprehensive histopathological comparison of EDMM and PNM. Recognition of the above histopathological associations should aid in the correct classification and staging of cutaneous melanoma. Epidermotropic metastatic melanomas may occasionally show an epidermal-only/epidermal-predominant pattern; accurate diagnosis requires prudent clinical correlation and, when necessary, ancillary molecular tests.

Multifocal BRAF(V600E)-Mutated Melanoma in situ on the Foot

Melanoma is an aggressive skin cancer that originates from melanocytes, and about one half of melanoma cases possess a BRAF mutation. Together with PD-L1 expression, the BRAF(V600E) mutation is one of the optimal therapeutic targets for the treatment of melanoma. In this report, we describe a case of multifocal melanoma in situ on the foot, which carried the p.V600E mutation in the BRAF gene. Interestingly, the spotted melanoma lesion is demarcated by normal skin, and in all spotted pigmented lesions, there were no signs of dermal invasion of melanoma cells or spontaneous regression. Our case presented atypical clinical features, which might correlate with the local mutations of BRAF gene and the immunological expression of PD-L1.

Dermoscopic patterns of melanoma metastases: interobserver consistency and accuracy for metastasis recognition

BACKGROUND

Cutaneous metastases of malignant melanoma (CMMM) can be confused with other skin lesions. Dermoscopy could be helpful in the differential diagnosis.

OBJECTIVES

To describe distinctive dermoscopic patterns that are reproducible and accurate in the identification of CMMM.

METHODS

A retrospective study of 146 dermoscopic images of CMMM from 42 patients attending a melanoma unit between 2002 and 2009 was performed. Firstly, two investigators established six dermoscopic patterns for CMMM. The correlation of 73 dermoscopic images with their distinctive patterns was assessed by four independent dermatologists to evaluate the reproducibility in the identification of the patterns. Finally, 163 dermoscopic images, including CMMM and nonmetastatic lesions, were evaluated by the same four dermatologists to calculate the accuracy of the patterns in the recognition of CMMM.

RESULTS

Five CMMM dermoscopic patterns had a good interobserver agreement (blue naevus-like, naevus-like, angioma-like, vascular and unspecific). When CMMM were classified according to these patterns, correlation between the investigators and the four dermatologists ranged from κ = 0.56 to κ = 0.7. In total, 71 CMMM, 16 angiomas, 22 blue naevi, 15 malignant melanomas, 11 seborrhoeic keratoses, 15 melanocytic naevi with a globular pattern and 13 pink lesions with a vascular pattern were evaluated according to the previously described CMMM dermoscopy patterns, showing an overall sensitivity of 67.9% (range 54.9-76%) and a specificity of 79.9% (range 68.5-93.5%) for the diagnosis of CMMM.

CONCLUSIONS

Five dermoscopic patterns of CMMM with good interobserver agreement obtained a high sensitivity and specificity in the diagnosis of metastasis, with the accuracy varying according to the experience of the observer.