The utilization of spitz-related nomenclature in the histological interpretation of cutaneous melanocytic lesions by practicing pathologists: results from the M-Path study

Impact of Next-generation Sequencing on Interobserver Agreement and Diagnosis of Spitzoid Neoplasms

Atypical Spitzoid melanocytic tumors are diagnostically challenging. Many studies have suggested various genomic markers to improve classification and prognostication. We aimed to assess whether next-generation sequencing studies using the Tempus xO assay assessing mutations in 1711 cancer-related genes and performing whole transcriptome mRNA sequencing for structural alterations could improve diagnostic agreement and accuracy in assessing neoplasms with Spitzoid histologic features. Twenty expert pathologists were asked to review 70 consultation level cases with Spitzoid features, once with limited clinical information and again with additional genomic information. There was an improvement in overall agreement with additional genomic information. Most significantly, there was increase in agreement of the diagnosis of conventional melanoma from moderate (κ=0.470, SE=0.0105) to substantial (κ=0.645, SE=0.0143) as measured by an average Cohen κ. Clinical follow-up was available in all 70 cases which substantiated that the improved agreement was clinically significant. Among 3 patients with distant metastatic disease, there was a highly significant increase in diagnostic recognition of the cases as conventional melanoma with genomics (P<0.005). In one case, none of 20 pathologists recognized a tumor with BRAF and TERT promoter mutations associated with fatal outcome as a conventional melanoma when only limited clinical information was provided, whereas 60% of pathologists correctly diagnosed this case when genomic information was also available. There was also a significant improvement in agreement of which lesions should be classified in the Spitz category/WHO Pathway from an average Cohen κ of 0.360 (SE=0.00921) to 0.607 (SE=0.0232) with genomics.

Pediatric melanoma in the Hispanic population: An analysis of institutional and national data

BACKGROUND/OBJECTIVES

Pediatric melanoma is rare and remains poorly characterized, especially in racial/ethnic minorities of whom Hispanics are the largest and fastest growing in the United States. The health care burden of melanoma in Hispanics, who often present with more advanced disease, is rising and has even been called an early epidemic in California. We sought to document key clinicopathologic features of melanoma in Hispanic pediatric patients and to compare these parameters to pediatric non-Hispanic whites (NHWs) under the a priori hypothesis that Spitzoid melanomas occur in greater proportions in Hispanics.

METHODS

Single-institution cross-sectional study of pediatric melanoma cases (age < 20 years) with Hispanic stratification and comparison with matched Surveillance, Epidemiology, and End Results (SEER) data from the same time frame (1988-2016).

RESULTS

Of our 61 institutional cases of pediatric melanoma, Hispanics (11), compared with NHWs (40), presented significantly younger (11.7 years, 95% CI: 2.77-8.00 years; P = .001), with lower limb predominance (46%; P < .05), mostly Spitzoid melanomas (82%; P < .05), and thicker tumors (2.34 mm, CI: 0.26-2.19 mm; P < .05). Similarly, SEER data (2499 cases) showed greater proportions of childhood/pre-pubertal adolescent melanomas (<15 years), lower limb involvement, Spitzoid subtype (36.5% vs 22.5% in NHWs; P = .001), and advanced (regional/distant) disease stages in Hispanics (212) compared with NHWs (2197).

CONCLUSIONS

Pediatric melanomas may present differently in Hispanics, and heightened awareness/lower threshold to biopsy high-risk Spitzoid tumors on the lower limb may be warranted. Further investigations are needed to aid prevention and early detection in a vulnerable minority population less likely to seek outpatient dermatology specialty care.

[Reed nevus and cutaneous melanoma in children: an immunohistochemical study]

Certain difficulties arise in the differential diagnosis between Reed nevus that is common in children and adolescents and cutaneous melanoma that is extremely rare in patients of this age group. In addition to the classical histological examination, an immunohistochemical test for marker proteins is carried out to improve the accuracy of the diagnosis of pigmented skin neoplasms.

OBJECTIVE

To evaluate the suitability of a set of proteins (cyclin D1, p16^INK4a, and HLA class I antigens) in the differential diagnosis of Reed nevus and cutaneous melanoma in children and adolescents.

MATERIAL AND METHODS

Three samples of pigmented skin neoplasms were taken during surgical treatment in patients at the Blokhin National Medical Research Center of Oncology: two samples of Reed nevus (from a 9-year-old girl and a 15-year-old boy) and a sample of cutaneous melanoma that had developed in an 8-year-old boy. The materials were presented by paraffin blocks. Immunohistochemical staining was performed using antibodies against cyclin D1, p16^INK4a, and HLA class I antigens.

RESULTS

Differences were found between nevus and melanoma in the expression of all three markers. Thus, the nuclear expression of cyclin D1, a proliferation activator, occurred in some cells in the nevus samples and in the vast majority of cells in the melanoma samples. The nuclear expression of the cell cycle inhibitor p16^INK4a was dramatically reduced in melanoma compared to nevus. HLA class I antigens were detected on the surface of individual nevus cells, but were completely absent on the membranes and in the cytoplasm of melanoma cells, which could promote the evasion of this tumor from the body's immunological supervision.

CONCLUSION

Immunohistochemical test for the proteins cyclin D1, p16^INK4a, and HLA class 1 antigens is a promising approach to differentially diagnosing between Reed nevus and cutaneous melanoma in children and adolescents.

Pediatric Melanoma-Diagnosis, Management, and Anticipated Outcomes

Melanoma is the most common skin cancer in children, often presenting in an atypical fashion. The incidence of melanoma in children has been declining. The mainstay of therapy is surgical resection. Sentinel lymph node biopsy often is indicated to guide therapy and determine prognosis. Completion lymph node dissection is recommended in selective cases after positive sentinel lymph node biopsy. Those with advanced disease receive adjuvant systemic treatment. Because children are excluded from melanoma clinical trials, management is based on pediatric retrospective data and adult clinical trials. This review focuses on epidemiology, presentation, surgical management, adjuvant therapy, and outcomes of pediatric melanoma.

What's new in pediatric melanoma: An update from the APSA cancer committee

BACKGROUND/PURPOSE

Melanoma is the most common skin cancer in children and often presents in an atypical fashion when compared to adults. The purpose of this review is to present an update on the epidemiology, surgical and medical management and prevention strategies in pediatric melanoma.

METHODS

A comprehensive review of the current literature on the epidemiology, surgical and medical management and prevention of adult and pediatric melanoma was performed by the authors and the results of this review are summarized in the manuscript.

RESULTS

Most recently, the incidence of melanoma in children has been declining, possibly owing to increased awareness and sun exposure prevention. The mainstay of therapy is surgical resection, often with sentinel lymph node biopsy. A positive sentinel node has prognostic value; however, completion node dissection is no longer recommended in the absence of clinically or radiographically positive nodes. Those with advanced disease also receive adjuvant systemic therapy using increasingly targeted immunologic therapies.

CONCLUSIONS

Sentinel lymph node positive patients no longer require completion lymph node dissection and instead may be followed by ultrasound. However, it is important to note that children have been excluded from most melanoma clinical trials to date, and therefore, recommendations for management are based on existing pediatric retrospective data and extrapolation from adult studies.

LEVEL OF EVIDENCE

IV.

Ciliation Index Is a Useful Diagnostic Tool in Challenging Spitzoid Melanocytic Neoplasms

The loss of primary cilia on melanocytes is a useful biomarker for the distinction of melanoma from conventional melanocytic nevi. It is unknown whether ciliation status is beneficial for diagnosing spitzoid tumors-a subclass of melanomas that present inherently ambiguous histology and are challenging to classify. We evaluated the Ciliation Index (CI) in 68 cases of spitzoid tumors ranging from Spitz nevi and atypical Spitz tumors to spitzoid melanoma. We found a significant decrease in CI within the spitzoid melanoma group when compared with either the Spitz nevi or atypical Spitz tumors groups. In addition, we used a machine-learning-based algorithm to determine the value of CI when considered in combination with other histopathologic and molecular features commonly used for diagnosis. We found that a low CI was consistently ranked as a top predictive feature in the diagnosis of malignancy. Predictive models trained on only the top four predictive features (CI, asymmetry, hyperchromatism, and cytologic atypia) outperformed standard histologic assessment in an independent validation cohort of 56 additional cases. The results provide an alternative approach to evaluate diagnostically challenging melanocytic lesions, and further support the use of CI as an ancillary diagnostic test.

Integrating Next-Generation Sequencing with Morphology Improves Prognostic and Biologic Classification of Spitz Neoplasms

The newest World Health Organization classification of skin tumors suggests the elimination of cases with BRAF and NRAS mutations from the categories of Spitz tumors (ST) and Spitz melanoma (SM). The objective of this study is to better characterize the genomics of Spitz neoplasms and assess whether the integration of genomic data with morphologic diagnosis improves classification and prognostication. We performed DNA and RNA sequencing on 80 STs, 26 SMs, and 22 melanomas with Spitzoid features (MSF). Next-generation sequencing data were used to reclassify tumors by moving BRAF and/or NRAS mutated cases to MSF. In total, 81% of STs harbored kinase fusions and/or truncations. Of SMs, 77% had fusions and/or truncations with eight involving MAP3K8. Previously unreported fusions identified were MYO5A-FGFR1, MYO5A-ERBB4, and PRKDC-CTNNB1. The majority of MSFs (84%) had BRAF, NRAS, or NF1 mutations, and 62% had TERT promoter mutations. Only after reclassification, the following was observed: (i) mRNA expression showed distinct clustering of MSF, (ii) six of seven cases with recurrence and all distant metastases were of MSFs, (iii) recurrence-free survival was worse in MSF than in the ST and SM groups (P = 0.0073); and (iv) classification incorporating genomic data was highly predictive of recurrence (OR 13.20, P = 0.0197). The majority of STs and SMs have kinase fusions as primary initiating genomic events. The elimination of BRAF and/or NRAS mutated neoplasms from these categories results in the improved classification and prognostication of melanocytic neoplasms with Spitzoid cytomorphology.

Genomic Landscape of Spitzoid Neoplasms Impacting Patient Management

Spitzoid neoplasms are a distinct group of melanocytic proliferations characterized by epithelioid and/ or spindle shaped melanocytes. Intermediate forms that share features of both benign Spitz nevi (SN) and Spitz melanoma, i.e., malignant Spitz tumor (MST) represent a diagnostically and clinically challenging group of melanocytic lesions. A multitude of descriptive diagnostic terms exist for these ambiguous lesions with atypical Spitz tumor (AST) or Spitz tumor of uncertain malignant potential (STUMP) just naming two of them. This diagnostic gray zone creates confusion and high insecurity in clinicians and in patients. Biological behavior and clinical course of this intermediate group still remains largely unknown, often leading to difficulties with uncertainties in clinical management and prognosis. Consequently, a better stratification of Spitzoid neoplasms in benign and malignant forms is required thereby keeping the diagnostic group of AST/STUMP as small as possible. Ancillary diagnostic techniques such as immunohistochemistry, comparative genomic hybridization, fluorescence in situ hybridization, next generation sequencing, micro RNA and mRNA analysis as well as mass spectrometry imaging offer new opportunities for the distinct diagnosis, thereby allowing the best clinical management of Spitzoid neoplasms. This review gives an overview on these additional diagnostic techniques and the recent developments in the field of molecular genetic alterations in Spitzoid neoplasms. We also discuss how the recent findings might facilitate the diagnosis and stratification of atypical Spitzoid neoplasms and how these findings will impact the diagnostic work up as well as patient management. We suggest a stepwise implementation of ancillary diagnostic techniques thereby integrating immunohistochemistry and molecular pathology findings in the diagnosis of challenging ambiguous Spitzoid neoplasms. Finally, we will give an outlook on pending future research objectives in the field of Spitzoid melanocytic lesions.

Influence of variability in assessment of Breslow thickness, mitotic rate and ulceration among US pathologists interpreting invasive melanoma, for the purpose of AJCC staging

BACKGROUND

Melanoma staging has depended on depth of invasion (Breslow thickness, BT), mitotic rate (MR) and ulceration. In anticipation of the AJCC's eighth edition, variability in pathologists' assessment of these factors and consequently in tumor staging was assessed.

METHODS

One-hundred and fifteen cases of invasive melanoma, established by a consensus panel, were assessed by 187 pathologists. Variation was studied in BT, the detection of mitotic figures, and ulceration. The sources of this variation and its effect on tumor staging are considered.

RESULTS

On average, participant assessments closely approached consensus BT. Greater variation was identified in the classification of mitogenicity, which (like ulceration) upstages a T1 melanoma from T1a to T1b in the seventh but not eighth edition. In cases with a T1a diagnosis by the consensus panel, 15.6% of participants identified one or more mitotic figures (indicative of a false positive); and in cases diagnosed asT1b by the consensus panel, 32.0% of participants failed to find mitotic figures (false negative).

CONCLUSION

Variability in the staging of T1 melanoma among pathologists when using the AJCC seventh edition criteria is closely related to the detection of mitotic figures, with BT playing a less prominent role. Decreased variability is expected after implementation of the eighth edition.

Common and not so Common Melanocytic Lesions in Children and Adolescents

The acquired melanocytic nevus is the most common lesion encountered by pediatric pathologists and dermatopathologists in their daily practice. In most cases, there are few difficulties in histopathologic diagnosis. However, it is the acquired melanocytic lesion known as the Spitz nevus, with its intrinsic atypical features which becomes the challenge since it exists along a histopathologic and biologic continuum from the atypical Spitz tumor to spitzoid melanoma. The frustration with some of these spitzoid lesions is that even the "experts" cannot agree as to the differentiation of one from the other even at the level of molecular genetics. Other melanocytic lesions are discussed including the congenital melanocytic nevus with its proliferative nodule(s) and melanoma as the ultimate complication. Although uncommon, cutaneous melanoma in the first 2 decades is emerging as a clinical problem especially in young women in the second decade of life. These are ultraviolet-associated neoplasms whose histopathologic and prognostic features are identical to the adult experience. Considerable progress has been made over the past 15 to 20 years in our understanding of cutaneous melanocytic lesions, but gaps still exist in the important group of spitzoid lesions. It can also be anticipated that more cutaneous melanomas in children will be seen in the future based upon epidemiologic studies.

Pathology and genomics of pediatric melanoma: A critical reexamination and new insights

The clinicopathologic features of pediatric melanoma are distinct from those of the adult counterpart. For example, most childhood melanomas exhibit a uniquely favorable biologic behavior, save for those arising in large/giant congenital nevi. Recent studies suggest that the characteristically favorable biologic behavior of childhood melanoma may be related to extreme telomere shortening and dysfunction in the cancer cells. Herein, we review the genomic profiles that have been defined for the different subtypes of pediatric melanoma and particularly emphasize the potential prognostic value of telomerase reverse transcriptase alterations for these tumors.

Pediatric melanoma: incidence, treatment, and prognosis

The purpose of this review is to outline recent advancements in diagnosis, treatment, and prevention of pediatric melanoma. Despite the recent decline in incidence, it continues to be the deadliest form of skin cancer in children and adolescents. Pediatric melanoma presents differently from adult melanoma; thus, the traditional asymmetry, border irregularity, color variegation, diameter >6 mm, and evolution (ABCDE) criteria have been modified to include features unique to pediatric melanoma (amelanotic, bleeding/bump, color uniformity, de novo/any diameter, evolution of mole). Surgical and medical management of pediatric melanoma continues to derive guidelines from adult melanoma treatment. However, more drug trials are being conducted to determine the specific impact of drug combinations on pediatric patients. Alongside medical and surgical treatment, prevention is a central component of battling the incidence, as ultraviolet (UV)-related mutations play a central role in the vast majority of pediatric melanoma cases. Aggressive prevention measures targeting sun safety and tanning bed usage have shown positive sun-safety behavior trends, as well as the potential to decrease melanomas that manifest later in life. As research into the field of pediatric melanoma continues to expand, a prevention paradigm needs to continue on a community-wide level.