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.

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.

[Clinicopathological features and prognosis of ALK-positive Spitz tumors].

Objective: To investigate the clinicopathologic features and prognosis of ALK-positive Spitz tumors. Methods: Thirteen patients with ALK-positive Spitz tumors diagnosed at Shanghai Cancer Center, Fudan University from October 2016 to December 2017 were collected. All cases were routinely evaluated histopathological features in HE staining and detected ALK protein expression by immunohistochemistry. The ALK fusions of 7 cases were confirmed by fluorescence in situ hybridization (FISH).Follow-up data was collected. Results: The age of patients including 2 males and 11 females ranged from 4 to 47 years (mean 25 years). 12 patients were diagnosed with atypical Spitz tumors and 1 patient was diagnosed with Spitz nevus. Clinically, most lesions presented as papules or nodules, while a few lesions presented as plaques. Histologically, most tumors were exophytic (9/13). More than half of the tumors were amelanotic and the junctional component was mainly composed of melanocytic nests. Kamino bodies were not found. The bases of the tumors were mainly wedge-shaped (5/13) and flat (7/13). Eight tumors displayed mixed cell types, while 5 tumors were composed of only spindle cells. All the tumors showed a plexiform and/or intersecting fascicular growth pattern, and perineural extension was observed in 3 tumors. ALK immunohistochemistry showed diffuse and intense cytoplasmic staining in 13 cases, and 7 of them were detected by FISH to confirm the presence of ALK fusions. All patients were followed up for 7 to 21 months (median=12), with no recurrence or lymph node dissemination. Conclusions: Spitz tumors with ALK fusions have their special histopathologic features.ALK fusions mainly occur in Spitz nevi and atypical Spitz tumors. The follow-up data of the existing literatures and our research indicates that the prognosis of ALK-positive Spitz tumors may be good.

Outcomes of atypical spitz tumors with chromosomal copy number aberrations and conventional melanomas in children.

Death due to melanoma in childhood (up to 20 y of age) is a rare event, with an average of 18 cases reported annually in the United States. In this study we evaluated 2 subgroups of high-risk melanocytic neoplasms in childhood, specifically atypical Spitz tumors (ASTs) with chromosomal copy number changes and conventional melanomas. We analyzed the clinical, histologic, and molecular features of all cases and performed the Fisher exact test, logistic regression, and multivariate analysis to evaluate features associated with aggressive clinical behavior in these cases. Among the ASTs, all of which had 1 or more chromosomal copy number aberrations, the presence of homozygous 9p21 deletions and a positive sentinel lymph node were each found to be correlated with tumor extension beyond the sentinel lymph node, with P-values of 0.046 and 0.01, respectively. Two patients with ASTs that had homozygous 9p21 deletions developed brain metastasis, one of whom died of disease. Among the 21 conventional melanomas, 3 patients developed distant metastasis and died of disease. Chromosomal copy number aberrations evaluated by fluorescence in situ hybridization were present in the majority of the cases (16/18). Among conventional melanomas, we did not identify any clinical, histologic, or molecular features associated with aggressive behavior. The presence of 8q24 gains was seen almost exclusively in 6 amelanotic small cell melanomas in children of whom 1 died of disease. Characteristic chromosomal copy number aberrations may occur in specific subtypes of melanocytic neoplasms in children and may help with the classification and prognostication of these rare tumors.

Sentinel lymph node biopsy in atypical Spitz nevi: is it useful?

AIMS: The aim of this study was to evaluate the incidence of lymph node metastases in patients with atypical Spitz nevi (ASN) after sentinel lymph node biopsy (SLNB) and during follow-up, and to assess the diagnostic value of the surgical procedure. METHODS: At the National Cancer Institute of Naples, Italy, 40 patients with ASN underwent SLNB between 2003 and 2011. Medical records were reviewed and all slides of the primary tumours were retrieved, rendered separately, and assessed by four experienced dermatopathologists from two different academic institutions. Each member of the review panel assessed slides separately without recourse to medical notes and blinded to each others' diagnosis. All patients were treated with wide local excision and SLN biopsy according to the standard procedure. All cases were followed up to assess outcomes. RESULTS: The original diagnosis of ASN was confirmed in all 40 cases. No sentinel node positivity was recorded, and no patients developed nodal involvement during a median follow-up of 46 months (range 16-103). All patients were alive and without evidence of locoregional or distant relapse at time of review. CONCLUSIONS: In our experience, ASN were not associated with metastatic potential. Surgical staging procedures are not justified and careful clinical surveillance is adequate.

Melanocytic tumors of uncertain malignant potential: results of a tutorial held at the XXIX Symposium of the International Society of Dermatopathology in Graz, October 2008.

Several reports demonstrated the difficulties and lack of agreement in the histopathologic diagnosis of particular melanocytic tumors (atypical Spitz tumors, atypical blue nevi, deep penetrating nevi). These lesions are often referred to as "melanocytic tumors of uncertain malignant potential" (MELTUMP). We studied a large number of such tumors to find out whether repeatable histopathologic criteria for distinction of benign from malignant cases exist. Fifty-seven cases of MELTUMP were classified within 3 groups according to behavior as follows: (a) favorable (no evidence of metastatic disease after a follow-up of > or = 5 y), (b) unfavorable (tumor-related death and/or large metastatic deposits in the lymph nodes and/or visceral metastases), (c) borderline (small nodal deposits of tumor cells < or = 0.2 mm). There were no significant differences in tumor thickness and presence or absence of ulceration between the different groups. The only 3 histopathologic criteria that were statistically different between the groups of favorable and unfavorable cases were presence of mitoses, mitoses near the base, and an inflammatory reaction, all of them found more frequently in cases with unfavorable behavior. The major outcome of this study of a series of "MELTUMPs" suggests as a preliminary observation that these lesions as a group exist and that they may be biologically different from conventional melanoma and benign melanocytic nevi. The terminology remains highly controversial, reflecting the uncertainty in classification and interpretation of these atypical melanocytic tumors.

Influence of age on survival in childhood spitzoid melanomas.

BACKGROUND: Melanoma occurring during childhood and adolescence is rare. Although a few limited studies suggest that the prognosis of childhood melanomas is similar to those in adults, and is dependent on the initial stage of the tumor, there is controversy with respect to the biologic behavior of childhood melanomas. Spitzoid melanoma is a subtype of melanoma with distinct clinical and histopathologic features. The prognosis of spitzoid melanoma in children, despite metastasis, has been suggested to be better than that observed in adults; however, this assertion remains controversial. Whereas a number of spitzoid melanomas with regional lymph node metastasis with no further progression have been reported, cases leading to widespread metastasis and fatal outcomes are also well documented. METHODS: A retrospective review of the literature was conducted between 1949 and 2006. A total of 82 cases of spitzoid melanoma with regional and/or widespread metastasis that occurred in children, 17 years of age and under, were selected for the analysis. RESULTS: The 5-year survival rate in children diagnosed with metastatic spitzoid melanomas between 0 and 10 years of age was 88% compared with 49% in those between 11 and 17 years of age. CONCLUSIONS: The findings support the notion that younger age (< or =10) may be associated with longer survival in children with metastatic spitzoid melanomas.