PRKC Fusion Melanocytic Tumors, a Subgroup of Melanocytic Tumors More Closely Aligned to Blue Nevi Than to PRKAR1A-inactivated Pigmented Epithelioid Melanocytomas.

Tumors morphologically classified as pigmented epithelioid melanocytomas (PEMs) are genomically diverse, with the 2 most common genomic subtypes being PRKC fusions or PRKAR1A inactivating mutations. PRKC fusions activate the Gαq/11 pathway similar to blue nevi. Conversely, inactivating mutations in PRKAR1A activate the Gαs pathway. We hypothesize that PRKC fusions have greater genomic overlap with blue nevi compared with PRKAR1A-inactivated PEMs. We characterized the clinical and morphologic features of 21 PRKC and PRKACB fusion melanocytic tumors and compared this to PRKAR1A mutated PEMs. To test our hypothesis regarding greater genomic overlap between PRKC fusions and blue nevi relative to PRKAR1A mutated PEMs, we performed a principal component analysis (PCA) using mRNA expression data. Lastly, we performed a meta-analysis focusing on the outcome data of PRKC fusions. PRKC fusions occur at a younger median age than PRKAR1A mutated PEMs (16 vs. 27). Histologically, PRKC fusions have solid aggregates of epithelioid melanocytes not typical of PRKAR1A mutated PEMs. The PCA plot showed no overlap between the PRKC fusion group and the PRKAR1A-mutated PEMs. There was a significant overlap between PRKC fusions and blue nevi. A meta-analysis of PRKC fusion cases in the literature suggests melanoma is uncommon, but the loss of BAP-1 nuclear expression may be associated with an adverse prognosis as in tumors from the blue nevus family. PRKC fusion melanocytic tumors have greater genomic overlap with blue nevi compared with PRKAR1A mutated PEMs. We recommend categorizing benign PRKC fusion melanocytic tumors as blue fusion nevi/tumors.

Atopic Dermatitis Across Shades of Skin.

Atopic dermatitis (AD) is a chronic, heterogeneous inflammatory skin disease that is associated with immense patient burden globally. There is increasing appreciation of disparities among patients identified as having skin of color (SOC), which often refers to patients of non-White race or non-European ancestry, but can broadly include individuals from a number of different racial, ethnic, ancestral, and skin pigmentation groups based on definition. In this narrative review, we discuss key terminology as it relates to AD across shades of skin, including modern definitions of 'race', 'ethnicity', and 'SOC'. We then synthesize the current literature describing disparities in AD prevalence, disease recognition, and burden alongside current data regarding genetic and immunologic findings across SOC populations. In the context of these findings, we highlight key concomitant social determinants of health, including environmental factors, socioeconomic status, and access to care, for which race often serves as a proxy for true biological and genetic differences. Finally, we discuss future efforts to shift to a more inclusive understanding of AD to encompass all shades of skin, to ensure equitable representation of diverse populations in high impact research, and intensify efforts to address the critical upstream factors driving observed disparities.

Capturing the Diversity of Dermatology-What's in a Name?

As research related to skin of color (SOC) in dermatology continues to grow, it is increasingly important to precisely define terminology. The terms 'SOC', 'race', and 'ethnicity' are frequently used to analyze differences in dermatologic disease onset, severity, and outcomes. These terms are used interchangeably, are ill-defined across research studies, and frequently conflate biologic and socially constructed categories. SOC has been thought to represent differing degrees of pigment or melanin in the skin, however skin pigment is quite variable among races and ethnicities. Furthermore, certain individuals with less skin pigment may socially consider themselves to be SOC, while the inverse is also true. Fitzpatrick skin phototype classifications in SOC dermatology, while commonly used as an objective measure of diversity, also present with numerous limitations and inaccuracies. We seek to highlight strengths and weaknesses of the current terminology used in SOC dermatology and recommend a more holistic understanding of reported differences, including a framework reflective of upstream socioeconomic, environmental, and historical factors that may be most relevant to reported associations.

Distinct genomic features in a retrospective cohort of mucosal, acral, and vulvovaginal melanomas.

BACKGROUND: Compared with sun-exposed melanomas, less is known regarding the pathogenesis of sun-protected melanomas. Sun-protected melanomas share many epidemiologic factors, but their genetic heterogeneity is not well studied. OBJECTIVE: We investigated the genomic profile of acral, mucosal, and vulvovaginal melanomas. We hypothesize that mucosal melanomas, recognized for their uniquely aggressive clinical behavior, have distinct genomic features. METHODS: We performed whole transcriptome messenger RNA and DNA (1711 genes) sequencing, messenger RNA expression profiling, tumor mutational burden, ultraviolet signature, and copy number variants analysis on 29 volar/digital acral, 7 mucosal, and 6 vulvovaginal melanomas. RESULTS: There was significant genetic heterogeneity, particularly in acral melanomas, with 36% having BRAF alterations, whereas other melanomas had none (P = .0159). Nonzero ultraviolet signatures were more frequent in acral melanomas, suggesting greater ultraviolet involvement. Mucosal melanomas formed a distinct group with increased expression of cell cycle and proliferation genes. Various targetable aberrations were identified, such as AURKA and ERBB2, in mucosal and acral melanomas, respectively. LIMITATIONS: The sample size was a small. CONCLUSION: There is significant genetic heterogeneity among sun-protected melanomas. Mucosal melanomas have upregulation in cell cycle and proliferation genes, which may explain their aggressive behavior. Ultraviolet radiation plays some role in a subset of acral but not other melanomas.

Long-term retinal vasculature abnormalities following intravitreal bevacizumab for retinopathy of prematurity.

PURPOSE: To report long-term fluorescein angiography (FA) findings in consecutive patients with type 1 retinopathy of prematurity (ROP) treated with intravitreal bevacizumab (IVB), whose ROP seemed to have resolved clinically. METHODS: Data were retrospectively collected for all patients with IVB-treated type 1 ROP who underwent an exam under anesthesia (EUA) and FA at 60 weeks post-gestational age (PGA) or older at a tertiary medical center between 2011 and 2020. FA results were reviewed for pathological vascular findings. RESULTS: Twenty-nine eyes of 16 patients were included. Mean gestational age and birth weight were 25.3 ± 1.5 weeks and 762.2 ± 189.8 g, respectively. The mean age at the time of EUA and FA was 23.4 ± 15.8 months. All eyes had a peripheral avascular zone and irregular peripheral branching. Vascular loops were seen in 27 eyes (93.1%) and vascular bulbs and anastomoses in 16 eyes each (55.2%). Additional abnormal findings included leakage (10 eyes, 34.5%), vessels crossing the fovea (5 eyes, 17.2%), tortuous arteries and veins (9 eyes, 31%, and 5 eyes, 17.2%, respectively), and neovascularization (2 eyes, 6.9%). When comparing patients who were less than or greater than 70 weeks PGA at follow-up, FA findings in the group with shorter follow-up were significant for more anastomoses and vascular bulbs (p = 0.002 and p = 0.024, respectively) and trended towards more leakage (45.5% vs. 27.8%, p = 0.331). CONCLUSION: The vast majority of IVB-treated type 1 ROP eyes suffered from vascular pathologies long after treatment. There may be long-term progression in the vascularization process of the retina in some cases.

A Series of RET Fusion Spitz Neoplasms With Plaque-Like Silhouette and Dyscohesive Nesting of Epithelioid Melanocytes.

ABSTRACT: Two distinct studies have shown that RET fusions are found in 3%-4% of Spitz neoplasms. RET fusions have been well described in papillary thyroid cancer, non-small-cell lung cancer, breast cancer, and soft-tissue mesenchymal tumors as well as some other neoplasms. However, there are no comprehensive descriptions to date of the characteristic morphologic, clinical, or genomic findings in RET fusion Spitz neoplasms. In this study, we identified 5 cases of RET fusion Spitz neoplasms. These tumors showed characteristic morphologic features which included plaque-like silhouette and monotonous epithelioid cytology with expansile and dyscohesive nesting. Four of 5 patients including 1 diagnosed as Spitz melanoma had clinical follow-up all of which was uneventful. Furthermore, we describe the genomic sequences in 4 of these cases, 2 of which have previously described KIF5B-RET fusion and 2 of which had a novel LMNA-RET fusion. We believe this report significantly contributes to our current knowledge regarding Spitz neoplasms and describes characteristics features which can help with recognition of the RET subgroup of Spitz.

Incorporation of dermoscopy improves inter-observer agreement among dermatopathologists in histologic assessment of melanocytic neoplasms.

Histopathologic assessment of melanocytic neoplasms is the current gold standard of diagnosis. However, there are well recognized limitations including inter-observer diagnostic discordance. This study aimed to determine if integrating dermoscopy with histopathology of melanocytic neoplasms impacts diagnosis and improves inter-observer agreement. We conducted a prospective cohort study in a pigmented lesion clinic. Consecutive melanocytic lesions were identified for biopsy based on atypical gross or dermoscopic features. Standardized immunohistochemistry and levels were ordered on each specimen. The cases were randomized. Three dermatopathologists blinded to the clinical impression assessed each lesion. The cases were then re-randomized and re-assessed with addition of gross clinical and dermoscopic images. Inter-rater reliability (IRR) using Fleiss' kappa statistic revealed an increase from 0.447 without to 0.496 with dermoscopy amongst all dermatopathologists. The kappa increased from 0.495 before to 0.511 with dermoscopy in separating high-grade atypia or melanoma from moderate atypia or less. In 16 of 136 cases, at least 2 of 3 dermatopathologists favored a diagnosis of melanoma only after dermoscopy. In total, the consensus grade of atypia changed in 24.3% (33/ 136) of cases thereby representing changes to excisional margins and patient follow up. This study is limited by the cohort size. Dermoscopy significantly impacts diagnosis and improves identification of early melanomas in high risk populations and improves inter-observer agreement.

Clinical, morphologic, and genomic findings in ROS1 fusion Spitz neoplasms.

The presence of a characteristic chimeric fusion as the initiating genomic event is one defining feature of Spitz neoplasms. Characterization of specific subtypes of Spitz neoplasms allows for better recognition facilitating diagnosis. Data on clinical outcomes of the specific tumor types may help in predicting behavior. In this study we present the largest series to date on ROS1 fusion Spitz neoplasms. We present the clinical, morphologic, and genomic features of 17 cases. We compared the morphologic features of these 17 cases to a cohort of 99 other non-ROS1 Spitz neoplasms to assess for features that may have high specificity for ROS1 fusions. These tumors consisted of ten Spitz nevi and seven Spitz tumors. None of the cases met criteria for a diagnosis of Spitz melanoma. Morphologically, the ROS1 fusion tumors of this series were characterized by a plaque-like or nodular silhouette, often densely cellular intraepidermal melanocyte proliferation, frequent pagetosis, tendency toward spindle cell cytomorphology, low grade nuclear atypia, and floating nests with occasional transepidermal elimination. However, there was a significant range in microscopic appearances, including two cases with morphologic features of a desmoplastic Spitz nevus. Different binding partners to ROS1 were identified with PWWP2A and TPM3 being the most common. No case had a recurrence or metastasis. Our findings document that most ROS1 fusion Spitz neoplasms have some typical characteristic microscopic features, while a small proportion will have features overlapping with other genomic subtypes of Spitz neoplasms. Preliminary evidence suggests that they tend to be indolent or low grade neoplasms.

BRAF fusion Spitz neoplasms; clinical morphological, and genomic findings in six cases.

BACKGROUND: Fusions involving the BRAF gene are responsible for 5% of Spitz neoplasms. To better characterize them, we report the clinical, morphological, and genomic findings of six BRAF fusion Spitz tumors. METHODS: The morphological, clinical, and molecular findings of six BRAF fusion Spitz neoplasms assessed by next generation sequencing (NGS) were compared to a control set of Spitz without BRAF fusions. RESULTS: BRAF fusion Spitz tumors had frequent predominance of epithelioid morphology (4/6 cases), frequent high-grade nuclear atypia and pleomorphism (5/6 cases), and a frequent desmoplastic base (3/6 cases). Five of six cases were diagnosed as atypical Spitz tumor and one as Spitz nevus. All cases had uneventful clinical follow-up. There were five different fusion partners, with CLIP2 being the most frequent. Secondary pathogenic mutations were frequent and chromosomal copy number changes were seen in three of six cases by an NGS platform. CONCLUSIONS: BRAF fusions Spitz usually have epithelioid morphology, high-grade nuclear atypia, and desmoplasia. Chromosomal copy number changes are not infrequent. While our cases had uneventful follow-up, a meta-analysis of the literature suggests that among the fusion subtypes associated with Spitz tumors, they are among the subgroups more likely to develop distant metastasis.

A retrospective cohort study of the diagnostic value of different subtypes of atypical pigment network on dermoscopy.

BACKGROUND: Atypical network encompasses several patterns. Few studies assess the sensitivity, specificity, and positive and negative predictive values of network subtypes. OBJECTIVE: We assessed the diagnostic value of atypical network subtypes and their histopathologic correlates in cutaneous melanocytic lesions. METHODS: A retrospective search (2014-2018) from a high-risk melanoma clinic for cases scored for atypical network with accompanying dermoscopic photographs yielded 120 lesions (15 melanoma; 30 severely, 38 moderately, and 32 mildly atypical nevi; 4 compound nevi; and 1 junctional nevus). A dermatopathologist blinded to diagnosis assessed dermoscopic and histologic features. Network abnormality correlates with histopathology and clinical diagnoses were assessed with sensitivity, specificity, positive and negative predictive values, and odds ratios. RESULTS: A multivariable model with shiny white streaks (odds ratio 3.02) and inverse network (OR 4.46) was most predictive of melanoma or severe atypia. Positive predictive value for melanoma or severe atypia in decreasing order was inverse network (73.9%), shiny white streaks (71.4%), loss of network (46%), branched streaks (29.4%), and thick brown lines (28.4%). LIMITATIONS: Cases were retrospectively found from a pigmented lesion clinic and evaluated by a single dermatopathologist. CONCLUSION: Shiny white streaks and inverse network are most predictive of melanoma or severe atypia and warrant biopsy if found on dermoscopy.

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.

Retrospective Cohort: Genomic Differences Between Pigmented Spindle Cell Nevi of Reed and Reed-Like Melanomas.

BACKGROUND: Some melanomas closely resemble pigmented spindle cell nevi (PSCN) of Reed histologically. The distinction of these entities is important for clinical management. A recent study showed most PSCN (78%) are fusion-driven, commonly involving NTRK3 (57%). Conversely, BRAF V600E mutations are not characteristic of PSCN but are frequent in melanoma. OBJECTIVE: In this study, we assessed clinical, histologic and genomic differences between PSCN of Reed and Reed-like melanomas (RLMs). METHODS: We performed BRAF V600E immunohistochemistry (IHC) for 18 PSCN and 20 RLM cases. All 23 benign PSCN cases previously underwent whole transcriptome and targeted DNA sequencing with a 1711 gene panel. RESULTS: We previously demonstrated the majority of PSCN (18 of 23) has chimeric fusions. Among PSCN without a chimeric fusion, BRAF mutations were common. Noncanonical BRAF mutations were identified in 2 of 5 nonfusion cases, and 1 case had a canonical BRAF mutation. Alternatively, 70% of RLM demonstrated a BRAF V600E mutation. RLM also occurred more frequently in older patients. LIMITATIONS: The overall sample size was small. CONCLUSIONS: In diagnostically challenging cases, ancillary IHC studies can assist in distinguishing PSCN from RLM. Our study suggests positive staining by IHC for BRAF V600E and older age strongly favors a diagnosis of RLM.

The role of gene fusions in melanocytic neoplasms.

Recent advances in next generation sequencing (NGS) have allowed for efficient whole transcriptome sequencing, leading to the identification of important kinase fusions as the primary driver in some melanocytic neoplasms. These fusions typically occur mutually exclusively of one another and other well-known initiating mutations such as BRAF, NRAS, NF1, KIT, and GNAQ. Fusions are found in over 50% of Spitz neoplasms, including ALK, BRAF, NTRK1, NTRK3, ROS1, MET, MAP3K8, and RET. Familiarity with the typical morphologic features of certain fusion-driven melanocytic neoplasms can help with classification, diagnosis, and identification of targeted molecular therapies in malignant cases. Spitz tumors with ALK, NTRK1, and NTRK3 fusions have characteristic morphologic features. BRAF and MAP3K8 fusions, in particular, tend to be epithelioid, high grade, and more frequent in Spitz melanoma than other fusion subtypes. Sporadic cases of pigmented epithelioid melanocytoma may have PRKCA fusions and sheets of monomorphic epithelioid melanocytes. Fusion events are also enriched among melanomas without the key mutations BRAF, NRAS, or NF1. Although NGS is the most reliable method to detect fusions, immunohistochemistry and fluorescence in situ hybridization are cost-effective alternatives in some cases. We describe recent discoveries regarding the role of kinase fusions in melanocytic neoplasms and their associated morphologies.

Activating Structural Alterations in MAPK Genes Are Distinct Genetic Drivers in a Unique Subgroup Of Spitzoid Neoplasms.

Recent studies have described kinase fusions as the most common initiating genomic events in Spitzoid neoplasms. Each rearrangement generates a chimeric protein with constitutive activation of the tyrosine kinase domain, resulting in the development of a Spitzoid neoplasm. Identifying key initiating genomic events and drivers may assist in diagnosis, prognostication, and management. Retrospective, consecutive search of our database between 2009 and 2018 for Spitzoid neoplasms identified 86 cases. Whole transcriptome mRNA and DNA sequencing (1714 genes) detected 9% of cases (8/86) with structural rearrangements in MAPK genes other than BRAF and 47% (40/86) with kinase fusions previously described in Spitzoid neoplasms. We identified in-frame fusions of MAP3K8-DIPC2, MAP3K8-PCDH7, MAP3K8-UBL3, MAP3K8-SVIL (n=6), and ATP2A2-MAP3K3 (n=1) as well as a p.I103_K104 in-frame deletion of MAP2K1 (n=1), in the absence of well-recognized drivers of melanocytic neoplasia. Fluorescence in situ hybridization validated all cases (n=7) with available tissue. Cases occurred in younger patients (median age 18 y). Morphologically, cases were predominantly epithelioid (P=0.0032), often with some melanin pigment (P=0.0047), and high-grade nuclear atypia (P=0.012). A significant proportion were thought to be Spitzoid melanomas (3/8). Average follow-up time was 11 months. One MAP3K8-DIP2C Spitzoid melanoma involved 4/5 sentinel lymph nodes and led to a complete lymph node dissection with unremarkable follow-up at 9 months. One MAP3K8-DIPC2 atypical Spitz tumor raised concern for recurrence at 10 months and was reexcised. We present a distinct subtype of Spitzoid neoplasm characterized by structural alterations in MAPK genes, which are important to recognize given the potential for treatment with MAPK inhibitors in metastatic cases.

Distinct Genomic Patterns in Pigmented Epithelioid Melanocytoma: A Molecular and Histologic Analysis of 16 Cases.

Pigmented epithelioid melanocytoma (PEM) is considered an intermediate grade melanocytic lesion that is histologically indistinguishable from epithelioid blue nevi associated with Carney complex. PEM are characterized by an intradermal population of heavily pigmented epithelioid-shaped melanocytes along with some spindled and dendritic melanocytes with frequent melanophages. These melanocytic tumors occasionally involve regional lymph nodes but only rarely result in distant metastases. Recent studies have demonstrated a variable but limited number of specific genomic aberrations including protein kinase A regulatory subunit alpha (PRKAR1A), BRAF, GNAQ, and MAP2K1 mutations as well as protein kinase C alpha isoform (PRKCA) fusions. We performed an 8-year retrospective review of our database and identified 16 cases of PEM. Using targeted DNA sequencing and RNA-seq to assess 1714 cancer-related genes, we detected gene fusions involving PRKCA in 31% of cases (5/16) with 5' partners SCARB1(12q24) in 2 cases, CD63 (12q13) in 1 case, ATP2B4 (1q32) in 1 case, and MAP3K3 (17q23) in 1 case. Additional fusions were identified in TPR-NTRK1 (1/16), ALK (1/16), and MYO5A-NTRK3 (1/16). PRKCA fusion lesions tended to occur in younger-aged patients and histologic examination demonstrated sheets of monomorphic epithelioid-shaped melanocytes, moderate to high-grade nuclear atypia, and higher mitotic activity (P=0.037). Our gene panel also identified previously described mutations in PRKAR1A, GNAQ, MAP2K1, BRAF, NF1. To our knowledge, this is the largest and most comprehensive study of PEM integrating molecular data with histologic features that can be utilized in future studies for improved subclassification and prognostication of heavily pigmented melanocytic neoplasms.