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BRCA1-associated protein 1 (BAP-1) is a deubiquitylase that functions as a tumor suppressor, regulating multiple cellular processes including cell cycle control, differentiation, cell death, and DNA repair. BAP-1-inactivated melanocytic tumors (BIMTs) have recently been described and are characterized by epithelioid cytomorphology, are often clonal in appearance, and typically do not recur or show malignant transformation on follow-up.To describe the histopathologic and molecular characterization of five cases of BAP-1-inactivated cutaneous malignant melanomas.The archives at two separate institutions were retrospectively searched for tumors classified as melanoma with loss of BAP-1 via immunohistochemistry. Five cases were identified. These cases were classified as malignant melanoma based on cytomorphology, immunohistochemistry, and ancillary molecular testing. The clinical demographics were recorded, along with the histomorphologic features of each case. Genomic analysis for all cases was performed via OncoScan.The five reviewed cases consisted of two females and three males ranging from 67 to 74 years in age. Molecular characterization of each case was performed using OncoScan. Microarray assay showed that there was a complete deletion of 3p in all cases, BRAF V600E mutation in two cases, NRAS missense variant in one case, and loss of 9p in three cases. All cases showed malignant copy number alterations.Herein we describe five cases of BAP-1-inactivated melanomas confirmed by histomorphology and immunohistochemistry, all of which show malignant copy number profiles including loss of 3p. In addition, we provide a case of a likely BIMT showing progression to BAP-1-inactivated melanoma on a 16-year follow-up.

BACKGROUND Cutaneous involvement by classic Hodgkin lymphoma (CHL) is an extraordinarily rare phenomenon in the current era. To date, no single large case series of cutaneous involvement by Hodgkin lymphoma has ever been reported in the literature. METHODS A comprehensive search for cases designated "skin" and "Hodgkin" was performed at different institutions between 1990 and 2020. Twenty-five cases were identified, and each case was independently reviewed by at least three board-certified dermatopathologists and/or hematopathologists. RESULTS All cases represented examples of systemic CHL with secondary skin dissemination. A single lesion, usually a tumor, nodule or infiltrative plaque was observed in 56% of cases and multiple lesions were present in 28% of cases. Most patients (86%-12/14) had a diagnosis of stage IV disease at first diagnosis. The interval between the clinical (first) diagnosis of HL and the development of skin lesions ranged between 6 and 108 months (average 33.75 months). Comprehensive histopathologic evaluation of these cases (at the initial diagnosis) revealed a diagnosis of classic HL not otherwise specified (NOS) in 60% of cases (15/25), nodular sclerosis type in 24% (6/25), mixed cellularity in 12% (3/25), and lymphocyte depleted in 4% (1/25). CONCLUSIONS We provide documentation of a large series of CHL with secondary skin involvement in association with CHL with additional clinical, morphologic, and immunophenotypic features.

Malignant peripheral nerve sheath tumor (MPNST) occurs either sporadically, in patients with neurofibromatosis type 1 (NF1), or following therapeutic radiation therapy; MPNST often arises from a peripheral nerve or a pre-existing neurofibroma.1,2 In addition to mutations in NF1 and CDKN2A, MPNST frequently harbors inactivating mutations in SUZ12 or EED, resulting in PRC2 (polycomb repressive complex 2) dysfunction and loss of histone H3 lysine 27 trimethylation (H3K27me3), most often seen in high-grade sporadic and radiation-associated tumors.2-4 Although the diagnosis of MPNST can be challenging, especially when there is neither a history of NF1 nor a clearly identifiable origin from a pre-existing neurofibroma, it can usually be recognized on the basis of the classic histological features, in conjunction with H3K27me3 loss by immunohistochemistry.

It is becoming increasingly important to obtain detailed diagnostic information on small-volume tissue biopsies, such as core needle biopsies. This is particularly crucial in the workup and diagnosis of classic Hodgkin lymphoma (CHL) and other morphologically similar lymphomas such as T-cell/histiocyte-rich large B-cell lymphoma (THRLBL), where small-volume lymph node biopsies often represent the frontline tissue source, and the differential diagnosis includes a reactive process. Immunohistochemical markers could be helpful to differentiate CHL from reactive lymph node changes (RLN) in this setting. The use of programmed cell death-1 (PD-1) and its ligand (PD-L1) immunohistochemistry has historically focused on prognostic and therapeutic value when evaluating CHL. However, the present study seeks to determine the diagnostic utility of these markers in core needle biopsies of CHL (25), THRLBL (3), and RLN (31). The cases of CHL and THRLBL were previously diagnosed and confirmed with standard immunohistochemistry, allowing the utility of PD-1 and PD-L1 to be tested in this setting. Different PD-1 and PD-L1 expression patterns were observed between the reactive process of RLN and the malignant lymphomas (CHL and THRLBL). CHL cases overall showed the greatest expression of PD-L1 within the malignant Reed-Sternberg cell population, with 40% of CHL cases exhibiting50% PD-L1 expression. This degree of PD-L1 expression was not seen in the lymphocytic cell population of any RLN (P0.001). Conversely, CHL cases showed an overall lower expression of PD-1, as 96% of CHLs had5% PD-1 expression in Reed-Sternberg cells compared with only 10% expression within the lymphocytic population of RLN (P0.001). THRLBL cases followed a similar trend to CHL. These results demonstrate that upfront PD-1 and PD-L1 immunohistochemistry can aid in the diagnosis of CHL in small-volume tissue biopsies.

Scalp cooling is a widely used method to prevent chemotherapy-induced transient alopecia. Although the success rates in maintaining hair can be high, authors have expressed their concerns regarding the risk of scalp metastasis after scalp cooling. We report a case of breast cancer scalp metastasis in a patient submitted to scalp cooling for alopecia prevention and discuss the physiopathology, risks and benefits of this treatment for patients under this treatment.

The archetypal solitary fibrous tumor (SFT) features fibroblastic cells with varying cellularity without any particular architectural arrangement in a collagenous matrix, with staghorn vessels, CD34 and STAT6 expression, and NAB2::STAT6. To date, this fusion is thought to be specific for SFT. With more routine use of fusion gene panels, the histologic diversity of NAB2::STAT6-positive tumors is increasingly appreciated. Here we present four head and neck tumors harboring NAB2::STAT6 but exhibiting remarkably unusual morphologic features for SFT. All cases were pulled from the authors’ consultation files. Immunohistochemistry was performed, along with targeted RNA sequencing in all cases, plus DNA next-generation sequencing on two. The cases arose in the nasal cavity (n = 2), retromolar trigone (n = 1) and parapharynx (n = 1), in patients ranging from 39 to 54 (mean, 44). Both nasal cases were biphasic, with a variably cellular collagenized stroma that resembled SFT but also interspersed malignant epithelial and neuroepithelial nests. One of the nasal cases also exhibited overt rhabdomyoblastic differentiation within both components. The two non-nasal cases were comprised of plump, epithelioid cells that were diffusely positive for pan-cytokeratin. One of these cases had prominent cystic change lined by overtly squamous epithelium. STAT6 immunostaining was positive in all cases, although the epithelial/neuroepithelial nests in the sinonasal cases were negative. All cases were confirmed to harbor NAB2::STAT6 by RNA sequencing. The two sinonasal cases were also found to harbor oncogenic mutations. The presented cases highlight a much broader histologic diversity than previously known for neoplasms with NAB2::STAT6. The biphasic nasal cases closely resemble teratocarcinosarcoma, while the epithelioid, cytokeratin-positive cases could be conceptualized as “adamantinoma-like,” to borrow terminology already in use for Ewing sarcomas with complex epithelial differentiation. To identify similar cases, pathologists should have a low threshold for using STAT6 immunohistochemistry on any difficult-to-characterize head and neck tumor.

We report a case of a 4-year-old Brazilian boy, who presented with an erythematous and painful nodule involving the skin of his left arm. Immunohistochemistry was performed for S100, SOX10, CD34, desmin, SMA, HMB-45, CD1a, and CD163, and fluorescence in situ hybridization for EWSR1 gene rearrangement using a break-apart probe was completed. Immunohistochemistry showed bland spindle cells with "floret-like" appearance simulating a giant cell fibroblastoma; tumor cells were positive for S100 and SOX10; neoplastic cells were negative for CD34, desmin, SMA, HMB-45, CD1a, and CD163; and fluorescence in situ hybridization showed an EWSR1 gene rearrangement. We report the youngest known case of cutaneous involvement of clear cell carcinoma at the age of 4.

Angiomatoid fibrous histiocytoma (AFH) is a rarely metastasizing neoplasm that typically occurs in the deep dermis and subcutis of the extremities of young patients, characterized by a t(2;22) translocation involving EWSR1 and CREB1. Because of its distinctive histologic features, the diagnosis of AFH is generally straightforward, although the immunohistochemistry (IHC) findings are relatively nonspecific. We recently encountered a case of primary cranial AFH that showed strong MUC4 IHC expression, which has not yet been reported previously. Prompted by this surprising finding, we investigated MUC4 expression in a series of AFH to evaluate this potential diagnostic pitfall. The expression of ALK by IHC, recently discovered in AFH, was also assessed in this study. We also analyzed EWSR1 rearrangement by fluorescence in situ hybridization using a dual color break-apart probe to confirm the diagnosis. The results showed MUC4 expression in 22.2% of AFH cases (4/18 cases), demonstrating a variable intensity of cytoplasmic staining. Most notably, one of the positive cases showed strong and diffuse expression. ALK IHC expression was observed in 17 of 18 cases (94.4%), usually in a diffuse and strong cytoplasmic pattern. EWSR1 rearrangement was demonstrated by fluorescence in situ hybridization in 81.2% of cases (13 of 16), including all the MUC4-positive cases. Our results indicate that although the significance of MUC4 expression in AFH is unknown, it is important to be aware that a subset of AFH can express the protein by IHC, expanding a variety of MUC4-positive mesenchymal tumors.

We report a primary renal synovial sarcoma with a novel gene fusion and unusual morphology. The patient was a 35-year-old female who was found to have a 5 cm hypocellular, myxoid spindle cell renal neoplasm that subtly permeated amongst native renal tubules. The tumor cells showed elongated hyperchromatic nuclei with ill-defined pale cytoplasm, lacking significant mitotic activity or necrosis. Based on its deceptively bland morphology, the differential diagnosis included mainly benign entities, such as metanephric stromal tumor, mixed epithelial stromal tumor (MEST), and myxoid peripheral nerve sheath tumors. A definitive diagnosis of synovial sarcoma was made only subsequently to RNA-sequencing, which revealed a novel SS18-NEDD4 gene fusion. These results were further confirmed by fluorescence in situ hybridization using custom design break-apart probes for both genes. This case illustrates the utility of targeted RNA-sequencing in the classification of challenging tumors with deceptive morphology and identification of novel gene fusion variants. Apart from the canonical SS18-SSX fusion, this is only the second alternative gene fusion variant described in synovial sarcoma to date, in addition to two cases harboring the SS18L1-SSX1 fusion.

Refractory celiac disease type II (RCD II), also referred to as "cryptic" enteropathy-associated T-cell lymphoma (EATL) or "intraepithelial T-cell lymphoma," is a rare clonal lymphoproliferative disorder that arises from innate intraepithelial lymphocytes. RCD II has a poor prognosis and frequently evolves to EATL. The pathogenesis of RCD II is not well understood and data regarding the immunophenotypic spectrum of this disease and underlying genetic alterations are limited. To gain further biological insights, we performed comprehensive immunophenotypic, targeted next-generation sequencing, and chromosome microarray analyses of 11 RCD II cases: CD4-/CD8- (n=6), CD8+ (n=4), and CD4+ (n=1), and 2 of 3 ensuing EATLs. Genetic alterations were identified in 9/11 (82%) of the RCD II cases. All 9 displayed mutations in members of the JAK-STAT signaling pathway, including frequent, recurrent STAT3 (7/9, 78%) and JAK1 (4/9, 44%) mutations, and 9/10 evaluable cases expressed phospho-STAT3. The mutated cases also harbored recurrent alterations in epigenetic regulators (TET2, n=5 and KMT2D, n=5), nuclear factor-κB (TNFAIP3, n=4), DNA damage repair (POT1, n=3), and immune evasion (CD58, n=2) pathway genes. The CD4-/CD8- and other immunophenotypic subtypes of RCD II exhibited similar molecular features. Longitudinal genetic analyses of 4 RCD II cases revealed stable mutation profiles, however, additional mutations were detected in the EATLs, which occurred at extraintestinal sites and were clonally related to antecedent RCD II. Chromosome microarray analysis demonstrated copy number changes in 3/6 RCD II cases, and 1 transformed EATL with sufficient neoplastic burden for informative analysis. Our findings provide novel information about the immunophenotypic and genomic characteristics of RCD II, elucidate early genetic events in EATL pathogenesis, and reveal potential therapeutic targets.

Background In Brazil, cancer is the second most common cause of death. Most patients in resource-limited countries are diagnosed in advanced stages. Current guidelines advocate for EGFR mutation testing in all patients with metastatic adenocarcinoma. Tyrosine kinase inhibitors are recommended in patients with advanced or metastatic disease harboring sensitizing mutations. In Brazil, there are limited data regarding the frequency of EGFR testing and the changes in patterns of testing overtime. Materials and Methods This was an observational, retrospective study. We obtained deidentified data from a commercial database, which included 11,684 patients with non-small cell lung cancer treated between 2011 and 2016 in both public and private settings. We analyzed the frequency of EGFR mutation testing over time. We also directly studied 3,664 tumor samples, which were analyzed between 2011 and 2013. These samples were tested for EGFR mutations through an access program to tyrosine kinase inhibitors in Brazil. Results Overall, 38% of patients were tested for EGFR mutations; 76% of them were seen in the private sector, and 24% were seen in the public center. The frequency of testing for EGFR mutations increased significantly over time: 13% (287/2,228 patients) in 2011, 34% (738/2,142) in 2012, 39% (822/2,092) in 2013, 44% (866/1,972) in 2014, 53% (1,165/2,184) in 2015, and 42% (1,359/3,226) in 2016. EGFR mutations were detected in 25.5% of analyzed samples (857/3,364). Deletions in Exon 19 were the most frequent mutations, detected in 54% of patients (463/857). Conclusion Our findings suggest that the frequency of EGFR mutation in this cohort was lower than that found in Asia but higher than in North American and Western European populations. The most commonly found mutations were in Exon 19 and Exon 21. Our study shows that fewer than half of patients are being tested and that the disparity is greater in the public sector. Implications for Practice These data not only indicate the shortage of testing but also show that the rates of positivity in those tested seem to be higher than in other cohorts for which data have been published. This study further supports the idea that awareness and access to testing should be improved in order to improve survival rates in lung cancer in Brazil.

More than 500 women worldwide have developed a CD30+ T-cell lymphoma around breast implants, strongly suggesting a cause-and-effect relationship, and designated as breast implant-associated anaplastic large cell lymphoma (BIA-ALCL). The mechanism of lymphomagenesis is unknown. Recently, a bacterial biofilm containing gram-negative bacilli was discovered on the surface of breast implants associated with ALCL. We and others have described overexpression of the proto-oncogene JUNB and mutations of JAK1/2, TP53 and STAT3 in BIA-ALCL. Here we report that BIA-ALCL cell lines and anaplastic lymphoma cells in clinical specimens produce IL-13, the signature cytokine of allergic inflammation. Supporting the link of BIA-ALCL to allergic inflammation, lymphoma cells were often surrounded by eosinophils and mast cells, features typically absent in systemic ALCL. Because of the link of IL-13 to allergy, we looked for IgE and found it decorating the surface of mast cells and antigen-presenting follicular dendritic cells in capsules and lymph nodes infiltrated by anaplastic lymphoma cells, but not uninvolved capsules. Plasma cells within capsules and regional lymph nodes were identified as a possible source of IgE. Together, these findings suggest the hypothesis that an amplified immune response with features of a chronic allergic reaction in a susceptible patient underlies the pathogenesis of BIA-ALCL.

Burkitt lymphoma (BL) is a B-cell lymphoma frequently diagnosed in children. It is characterized by MYC translocations, which lead to the constitutive expression of the MYC oncogene. MYC contributes to miR-29 repression through an E-box MYC binding site on the miR-29b-1/miR-29a promoter region. We evaluated the role of miR-29a/b/c and their predicted targets in BL pathogenesis. Mature sequences of miR-29a/b/c were transfected to the BL cell lines BL41 and Raji, and evaluated for DNMT3B, MCL1, BIM, CDK6, AKT and TCL1 protein expression as well as for MCL-1 and CDK6 mRNA expression. BL cells were treated with 5-aza-2′-deoxycytidine (decitabine) and evaluated for miR29 expressions and methylation status. DNMT3B inhibition was performed by DNMT3B siRNA. Ectopic expression of miR-29s in BL cells decreased CDK6, DNMT3B, TCL1 and MCL-1 protein levels, but CDK6 and MCL-1 mRNA expression was unaffected by miR-29. Decitabine enhanced miR-29 expression levels and decreased CDK6 protein expression. Additionally, inhibition of DNMT3B by siRNA increased miR-29a/b expression. Notably, the miR-29a/b1 and miR-29b2/c promoter genes showed methylated CpG sequences that were demethylated after decitabine treatments. Furthermore, MYC-negative tumours had higher levels of miR-29 expression compared with MYC-translocated cases, suggesting that MYC regulates miR-29 in BL tumours. Our results suggest a significant role for miR-29s in BL pathogenesis in altering the expression of targets involved in critical cancer pathways, such as cell cycle control, apoptosis inhibition and DNA methylation. Moreover, methylation-mediated miR-29 epigenetic silencing may occur during BL development.

Introduction Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematological malignancy with multi-organ and frequent skin involvement, and poor clinical outcomes. Based on the limited available data, the estimated incidence is 0.44% of all hematologic malignancies, representing less than 1% of acute leukemias, and 0.7% of cutaneous lymphomas. Due to the rarity of this entity, there have been relatively few studies characterizing the molecular profile of BPDCN. We examined a cohort of 51 patients with BPDCN using OncoScan chromosome microarray, which provides genome-wide copy number abnormality (CNA) analysis. Methods An international cohort of BPDCN cases were collected from centers in Brazil (Laboratorio de Patologia, Botucatu), Swtizerland (University of Zurich), France (Hospital St. Louis, Paris), Peru (Instituto Nacional de Enfermedades Neoplasicas, Lima), Canada (Department of Pathology, University of Montreal), Italy (Derpartment of Pathology, University of Bologna), and US (Department of Pathology - The Ohio State University, Department of Hematopathology - MD Anderson Cancer Center; and Department of Pathology - University of Virginia). A total of 58 tissue blocks from 51 patient samples were retrieved. The diagnosis of BPDCN was done and confirmed by at least three independent hematopathologists or dermatopathologists in accordance with the WHO classification (Lyon 2017). For the purpose of the molecular analysis substratification, cases were classified as 'BPDCN' if they were positive for TCF4, and 'BPDCN-like' if they were negative for TCF4. Immunohistochemistry for CD123, CD4, and CD56 was performed in all cases. Exclusion criteria included expression of MPO, lysozyme, CD3, CD19, CD20, CD22, and/or EBV. DNA was extracted from FFPE samples via standard techniques and processed on OncoScan CNV Plus microarray (ThermoFisher Scientific) according to manufacturer's recommended protocol. Copy number abnormalities and select single nucleotide variants and insertions/deletions (74 mutations in 9 genes) were analyzed on Chromosome Analysis Suite software (ChAS v4.1; ThermoFisher Scientific). Additional analysis was performed using Nexus Copy Number (BioDiscovery, version 10.0). Results To date, we have successfully analyzed 45 cases of BPDCN with Oncoscan, revealing widespread CNA in the vast majority of cases (44/45; 98%). Alterations of chromosome 9 were common in this cohort, particularly CNAs involving CDKN2A/B at 9p21.3. Twenty-five cases (56%) demonstrated CNA including CDKN2A/B, with ten of these cases demonstrating a homozygous loss of CDKN2A/B (22%). Alterations of chromosome 13 were also frequently detected with loss of RB1 (located at 13q14.2) detected in 24 cases (53%). The RUNX1 gene (21q22.12) was a common target of CNAs in this cohort, seen in nine cases (20%). Eight of these cases showed a copy number gain of RUNX1, which is a recurrent finding in a variety of hematological malignancies, particularly myeloid neoplasms. The remaining case with RUNX1 CNA showed a focal, homozygous loss of the gene, demonstrating that dysregulation of RUNX1 through CNA is a common event in BPDCN. We observed frequent deletions of ETV6 (53%), IKZF1 (33%), and TP53(16%) in our cohort. The ARHGAP26 gene (5q31.3), which is associated primarily with juvenile myelomonocytic leukemia, was included in CNA in 13 cases (29%), with both gains and losses observed in this cohort. Oncoscan can detect a limited number of single nucleotide variants in nine genes that are frequently mutated in cancers (BRAF, EGFR, IDH1, IDH2, KRAS, NRAS, PIK3CA, PTEN, and TP53). Mutations were detected in ten cases (22%), with NRAS and TP53 variants detected in three cases each and KRAS and IDH2 variants detected in two cases each. Conclusions Our preliminary data demonstrates complex genomic alterations in BPDCN, with the RB1 locus on chromosome 13, the CDKN2A/B locus on chromosome 9, and the ETV6 locus on chromosome 12 most commonly detected. However, widespread genomic alterations were detected involving a variety of cancer-associated genes further characterizing CNA in BPDCN. Analysis of additional BPDCN cases is progress. Disclosures Khoury: Kiromic: Research Funding; Angle: Research Funding; Stemline Therapeutics: Research Funding. Porcu: Viracta: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Innate Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; Daiichi: Honoraria, Research Funding; Kiowa: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Spectrum: Consultancy; DrenBio: Consultancy. Gru: StemLine: Honoraria, Research Funding, Speakers Bureau; CRISPT Therapeutics: Research Funding; Innate Pharma: Research Funding.

We report 2 primary renal sarcomas demonstrating BCOR-CCNB3 gene fusions that have recently been identified in undifferentiated round cell sarcomas of bone and soft tissue. These neoplasms occurred in male children aged 11 and 12 years, and both were cystic as a result of entrapment and dilatation of native renal tubules. Both cases were composed of variably cellular bland spindle cells with fine chromatin set in myxoid stroma and separated by a branching capillary vasculature. Both neoplasms demonstrated immunoreactivity for BCOR, cyclin D1, TLE1, and SATB2 in the spindle neoplastic cells and negativity in the prominent capillary vasculature. One case was extensively cystic and had hypocellular areas that simulated cystic nephroma; this neoplasm recurred 3 years later as a solid, highly cellular spindle cell sarcoma in the abdominal cavity. The morphology and immunoprofile of these renal neoplasms was compared with a control group of other sarcomas with BCOR genetic abnormalities, including clear cell sarcoma of the kidney (CCSK), infantile undifferentiated round cell sarcomas of soft tissue/primitive myxoid mesenchymal tumor of infancy, and bone/soft tissue sarcomas with BCOR-CCNB3 gene fusion; along with primary renal synovial sarcoma. Our findings show that the renal sarcomas with BCOR-CCNB3 gene fusion overlap with CCSK. These results are in keeping with a "BCOR-alteration family" of renal and extrarenal neoplasms which includes CCSK and undifferentiated round cell sarcomas of soft tissue/primitive myxoid mesenchymal tumor of infancy (which typically harbor BCOR internal tandem duplication), and BCOR-CCNB3 sarcomas, all of which are primarily driven by BCOR overexpression and have overlapping (but not identical) clinicopathologic features.

Objectives The aim of this study was to assess the association between DNA mismatch repair protein MLH1 status and classical prognostic factors in patients with endometrioid endometrial carcinoma. Methods We studied 47 consecutive patients aged 37–88 (61.34±10.52) with confirmed diagnosis of endometrial carcinoma of endometrioid type. The tumors were classified according the WHO 2014 criteria and graded using the FIGO system. The following pathological characteristics were analyzed: tumor size (mm), percentage of myometrial infiltration, presence of microcystic, elongated, and fragmented (MELF) pattern of myoinvasion, percentage of tumoral infiltrating lymphocytes (TILs), and lymph-vascular space invasion (LVSI). Deficiency of MLH1 protein was defined as complete loss of nuclear expression within tumor cells in the presence of positive internal controls in lymphocytes and/or stroma. The chi-square test and the Mann-Whitney U test were used to compare the groups with and without MLH1 loss. Results Loss of MLH1 was observed in 18/47 (38.3%) patients. Age of patients did not differ between MLH1-negative and MLH1-positive tumors (61.2±11.0 years and 61.4±10.4 years, respectively). The comparison of characteristics of the tumors with and without MLH1 loss is summarized in table 1. Conclusions Loss of MLH1 was associated with bigger tumors, MELF pattern of myoinvasion, and positive lymph nodes. Tumors with MLH1 loss presented more myometrial infiltration, more LVSI, and more TILs, although it did not reach a statistical level of significance. The presence of higher percentage of TILs, as well MLH1 loss itself, may indicate immunotherapy susceptibility.

Mammary analogue secretory carcinoma (MASC) is a relatively recently described salivary gland adenocarcinoma characterized by ETV6-NTRK3 gene fusion and in most cases indolent clinical behavior. The majority of tumors show an admixture of microcystic, solid, and tubular growth patterns but only a few cases with dominant macrocystic growth have been reported. We report 15 cases of macrocystic MASC. There were 11 men and 4 women (17 to 88 y age range, average 47 y). The patients presented with a painless cystic mass, the majority in the region of the parotid gland (n=13), as well as in submandibular gland (n=1) and the neck (n=1). All tumors were circumscribed measuring 1.0 to 4.0 cm in greatest diameter (mean: 1.75 cm). Twelve tumors were unilocular, while 3 were multilocular. The cystic spaces were predominantly lined by a single epithelial cell layer with focal areas in which the epithelium was multilayered with papillary and hobnail features. In 3 of the cases there were more solid foci of intracystic tumor characterized by papillary and/or microcystic growth. The neoplastic cells were round to oval with hyperchromatic to vesicular nuclei with centrally located nucleoli and eosinophilic or vacuolated cytoplasm. Tumor cells showed strong positivity for S100 protein and mammaglobin, while DOG1 was uniformly negative. A minority of cases showed focal p63 reactivity predominantly limited to the periphery of the cystic lining. ETV6 gene rearrangement was identified in 9 cases. Macrocystic MASC can simulate benign and malignant salivary gland lesions and needs to be included in the differential diagnosis of cystic lesions in the head and neck. To the best of our knowledge, our report represents the first series of macrocystic MASCs wholly focusing on this unusual variant.

// Anthony B. Eason 1, 2 , Sang-Hoon Sin 1, 2 , Carolina Lin 1, 2 , Blossom Damania 1, 2 , Steven Park 1, 3 , Yuri Fedoriw 1, 4 , Carlos E. Bacchi 5 , Dirk P. Dittmer 1, 2 1 Lineberger Comprehensive Cancer Center, the University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA 2 Department of Microbiology and Immunology, the University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA 3 Department of Medicine, the University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA 4 Department of Pathology and Laboratory Medicine, the University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA 5 Pathology Reference Laboratory, Botucatu, Sao Paulo, Brazil Correspondence to: Dirk P. Dittmer, email: ddittmer@med.unc.edu Keywords: Burkitt lymphoma, Epstein-Barr virus, IgM, Myc, ibrutinib Received: May 23, 2016 Accepted: August 13, 2016 Published: August 23, 2016 ABSTRACT Endemic Burkitt lymphoma (eBL) is primarily a childhood cancer in parts of Africa and Brazil. Classic studies describe eBL as a homogeneous entity based on t(8;14) IgH-Myc translocation and clinical response to cytotoxic therapy. By contrast, sporadic BL (sBL) in Western countries is considered more heterogeneous, and affects both children and adults. It is overrepresented in AIDS patients. Unlike diffuse large B cell lymphoma (DLBCL), molecular subtypes within BL have not been well defined. We find that differential IgM positivity can be used to describe two subtypes of pediatric Burkitt lymphoma both in a high incidence region (Brazil), as well as in a sporadic region (US), suggesting the phenotype is not necessarily geographically isolated. Moreover, we find that IgM positivity also distinguishes between early and late onset BL in the standard Eμ-Myc mouse model of BL. This suggests that the t(8;14) translocation not only can take place before, but also after isotype switch recombination, and that IgM-negative, t(8;14) positive lymphomas in children should nevertheless be considered BL.

Burkitt lymphoma (BL) is an aggressive B cell lymphoma characterized by the reciprocal translocation of the c-Myc gene with immunoglobulin genes. Recently, MYC has been shown to maintain the neoplastic state via the miR-17-92 microRNA cluster that suppresses chromatin regulatory genes and the apoptosis regulator Bim. However, the expression and prognostic impact of miR-17-92 members in pediatric BL (pBL) are unknown. Therefore, we investigated miR-17, miR-19a, miR-19b, miR-20, and miR-92a expression and prognostic impact in a series of 41 pBL samples. In addition, Bim protein expression was evaluated and compared to miR-17, miR-19a, miR-19b, miR-20, and miR-92a levels and patient outcomes. The expression of miR-17-92 members was evaluated by qPCR and Bim protein by immunohistochemistry. Log-rank test was employed to assess prognostic impact. We found that upregulated expression of miR-17 and miR-20a correlates with lack of pro-apoptotic Bim expression. Patients bearing tumors with upregulated miR-17 displayed decreased overall survival (OS), and multivariate analysis revealed that miR-17 was a significant predictor of shortened OS. Using hairpin inhibitors, we showed that inhibition of miR-17 resulted in enhanced Bim expression in a BL cell line overexpressing the miR-17-92 cluster. Our results describe for the first time miR-17, miR-19a, miR-19b, miR-20a, and miR-92a expression profiles in pBL. The prognostic impact of miR-17 should be validated in a larger series, and may provide new therapeutic avenues in the era of anti-miRNA therapy research. Additional functional studies are further required to understand the specific role of miR-17-92 cluster members in BL.

Desmoplastic melanoma (DM) is histologically characterized by a proliferation of spindle melanocytes dispersed in a collagenous stroma that can be mistaken for a variety of neoplasms. The purpose of this study was to analyze 40 cases of DM with a comprehensive panel of immunohistochemical markers (KBA.62, p16, Ezrin, WT-1, MITF-1, SOX-10, CD117, SOX-2, nestin, PNL2, p75, MART-1, gp100 and S100p) to obtain a more complete understanding of the potential use of these antibodies in the diagnosis of DM. We found that all cases of DM expressed p16, WT-1, SOX-10, nestin and S100p and 95% of cases expressed p75. There was variable expression with Ezrin, SOX-2, KBA.62, MART-1 and HMB-45. Most DMs did not express MITF-1, PNL2 and CD117. Conditions that may enter in the histologic differential diagnosis of DM, including dermal scars, fibromatosis and dermatofibromas were also studied. Nearly all control cases also stained positive for p16 but were negative for WT1, SOX10, nestin, p75 and S-100p, as well as for most of the other markers tested. We conclude that a panel of S-100p, WT1, SOX10, p75 and nestin may constitute the optimal panel with the most sensitive and specific combination of immunostain available for the diagnosis of DM.

Deregulation of microRNA expression plays a significant role in several cancer types including Burkitt lymphoma (BL). MicroRNA genes may be regulated through epigenetic mechanisms, such as specific histone modifications and/or DNA methylation of CpG islands in promoter regions, or by regions that are located next to microRNA genes. Given the regulatory role of MYC in miR‑29 expression, methylation as an additional mechanism for miR‑29 silencing was investigated. Methylation of miR‑29a/b/c in BL tumour samples and BL cell lines (BL41 and Raji) was assessed by pyrosequencing assay. BL cells were treated with 5‑aza‑2'‑deoxicitidine (decitabine) and evaluated for miR‑29a/b/c expression and methylation status. MYC, DNMT1 and DNMT3B protein expression were accessed by western blotting. For Epstein‑Barr virus (EBV) microRNA (miR)‑BART6 inhibition, the cells were transiently transfected with anti‑BART6‑5p. BL tumour samples and BL cell lines presented miR‑29a/b1 and miR‑29b2/c genes methylated in CpG sites located in both the promoter and enhancer regions. The treatment of BL cells with decitabine reduced methylation, induced miR‑29s expression and downregulated MYC protein levels in a dose‑dependent manner. Notably, inhibition of EBV miR‑BART6‑5p combined with decitabine enhanced miR‑29 expression in an EBV‑BL cell line. In conclusion, the miR‑29a/b1 and miR‑29b2/c genes have methylated CpG sequences at promoter and enhancer regions that may contribute to the regulation of miR‑29 expression in BL tumours. The present findings indicated interplay between MYC and miR‑29 regulation, highlighting the potential role of EBV‑miRNAs in miR‑29 regulation for BL pathogenesis.

Background Recently, we came with the theory of a possible relationship between a group of testicular and pancreatic tumors. We used one case of a pancreatic analogue solid pseudopapillary neoplasm of the testis composed partially of areas reminiscent of solid pseudopapillary neoplasm (SPN) of the pancreas and partially of structures identical to primary signet ring stromal tumor of the testis (PSRSTT) as a connecting link between these two entities. After demonstrating that PSRSTT and pancreatic analogue SPN of the testis share the same immunoprofile and genetic features characteristic for pancreatic SPN, we came to the conclusion that pancreatic analogue SPN of the testis and PSRSTT represent a morphological spectrum of a single entity and that both are related to the pancreatic SPN. Design The aim of this study is to present a series of 6 cases of testicular tumors, which lacked the signet ring cell component and were thus morphologically very similar to the SPN of the pancreas. The goal of this study is to compare the genetic background of these testicular tumors that are obviously related to the PSRSTT/pancreatic analogue SPN of the testis with the series of 8 pancreatic SPN. Results The mutational analysis revealed an oncogenic somatic mutation in the exon 3 of the CTNNB1 (β-catenin) gene in all analyzable (5/6) testicular and all pancreatic (8/8) tumors. The immunoprofile (positivity with β-catenin, CD10, vimentin, NSE, CD56, and negativity with inhibin, calretinin, chromogranin) was identical in all testicular and pancreatic tumors. Conclusion This study expanded the morphological spectrum of the PSRSTT/pancreatic analogue SPN of the testis by adding 6 cases without the signet ring cell component. Considering the obvious analogy of PSRSTT/pancreatic analogue SPN of the testis/SPN of the testis and their relationship to the pancreatic SPN we propose the collective term “solid pseudopapillary neoplasm of the testis” for these tumors. The mutational profile of the SPN of the testis and pancreas was the same in both groups of tumors which we consider as a final proof that SPN of the testis is identical to the SPN of the pancreas.

Less than 250 extraneuraxial hemangioblastomas occurring in paraneuraxial or peripheral sites have been reported to date, sporadically or in the setting of von Hippel-Lindau disease. Seventeen such cases underwent molecular genetic analysis, using either the patient's peripheral blood in 9 cases or paraffin embedded tumor tissue in the rest. VHL gene mutations were documented in 3/9 cases in which DNA from peripheral blood lymphocytes was used, all with clinically manifest von Hippel-Lindau disease; instead, no VHL gene alterations were found in all of the 8 cases with sporadic extraneuraxial hemangioblastoma in which DNA from tumor tissue was analyzed. Our aim is to investigate the molecular genetic profile of the VHL gene in extraneuraxial hemangioblastoma using paraffin embedded tumor tissues. The clinical features, histopathology, and molecular investigations of 10 extraneuraxial hemangioblastomas (7 females, 3 males; median age: 47 years) are presented herein. The histopathologic diagnosis was supported by immunohistochemistry (10/10) and electron microscopy (4/10). Molecular genetic analysis was conducted (10/10) for VHL gene mutations, LOH, and gene promoter methylation. Two of the present cases were already published with only limited or no molecular investigations. Four tumors of the present series were paraneuraxial, and 6 peripheral (2 involved soft tissues, and 4 the kidney). One tumor was von Hippel-Lindau disease-associated, 1 was classified as "hemangioblastoma-only VHLD", 7 were sporadic, and one was unknown. All were histopathologically analogous to their counterpart located inside the central nervous system. Immunophenotypically, all tumors expressed vimentin, S-100, NSE, and alpha-inhibin (10/10). Ultrastructurally, unbound lipid droplets filled the cytoplasms of the stromal cells. Molecular analysis revealed 3 inactivating mutations (1 germline, two somatic) in the coding sequence of the VHL gene in 2 different extraneuraxial hemangioblastomas, and LOH in 4 (two as a double hit), all non-renal extraneuraxial hemangioblastomas. Methylation analysis failed to disclose promoter methylation in any case. In conclusion, we report eight new cases from the wide category of extraneuraxial hemangioblastomas (4 paraneuraxial, and 4 renal), one of which was von Hippel-Lindau disease-associated and 7 sporadic. VHL gene alterations were found not only in the von Hippel-Lindau disease-associated tumor, but - for the first time - also in 3 sporadic ones, two of which with novel mutations.

Background Breast cancer in young women has different clinical and pathologic features and a more aggressive biological behavior when compared to breast cancers in older women. However, information is limited to the group of very young women (≤25 years). Objectives The aim of the present study was to investigate the pathological characteristics of breast cancer in 149 Brazilian women who were ≤25 years old at the time of breast cancer diagnosis. Materials and methods Tumor samples diagnosed between 2003 and 2009 were analyzed from the archives of the Bacchi Laboratory. Results In our series of 149 Brazilian women ≤25 years, 8.7% presented with in situ disease only. Of 136 invasive carcinomas, 91.9% were of the ductal type and 45.6% were of histological grade III. Overall, estrogen receptor (ER) was positive in 59.6% cases, and HER2 overexpression was detected in 32.8%. We also found a low prevalence of Luminal A cases and a high prevalence of Triple Negative cases. Statistical analysis showed that HER2 and basal-like groups had a lower overall survival expectation. Follow-up data showed high frequencies of regional lymph node metastasis, distant metastasis, and tumor-related deaths. Conclusion The present study represents the largest series of breast cancer arising in women ≤25 years and establishes the main clinical, pathological, immunohistochemical and follow-up features of this population.

CDKN2A is a tumor suppressor gene critical in the cell cycle regulation. Little is known regarding the role of CDKN2A methylation in the pathogenesis of Burkitt lymphoma (BL). CDKN2A methylation was investigated using pyrosequencing in 51 tumor samples. p16(INK4a) mRNA and protein levels were measured using real-time PCR and immunohistochemistry, respectively. CDKN2A methylation was detectable in 72% cases. Nuclear expression of p16(INK4a) was not detected in 41% cases. There was an association between methylation and absence of CDKN2A mRNA (P=0.003). In conclusion, CDKN2A methylation occurs at a high frequency suggesting a role in BL pathogenesis and potential therapeutic implications.

Extraneuraxial hemangioblastoma occurs in nervous paraneuraxial structures, somatic tissues, and visceral organs, as part of von Hippel-Lindau disease (VHLD) or in sporadic cases. The VHL gene plausibly plays a key role in the initiation and tumorigenesis of both central nervous system and extraneuraxial hemangioblastoma, therefore, the underlying molecular and genetic mechanisms of the tumor growth are initially reviewed. The clinical criteria for the diagnosis of VHLD are summarized, with emphasis on the distinction of sporadic hemangioblastoma from the form fruste of VHLD (eg, hemangioblastoma-only VHLD). The world literature on the topic of extraneuraxial hemangioblastomas has been comprehensively reviewed with ∼200 cases reported to date: up to 140 paraneuraxial, mostly of proximal spinal nerve roots, and 65 peripheral, 15 of soft tissue, 6 peripheral nerve, 5 bone, and 39 of internal viscera, including 26 renal and 13 nonrenal. A handful of possible yet uncertain cases from older literature are not included in this review. The clinicopathologic features of extraneuraxial hemangioblastoma are selectively presented by anatomic site of origin, and the differential diagnosis is emphasized in these subsets. Reference is made also to 10 of the authors' personal cases of extraneuraxial hemangioblastomas, which include 4 paraneuraxial and 6 peripheral (2 soft tissue hemangioblastoma and 4 renal).

Objectives KLHL6 is a recently described BTB-Kelch protein with selective expression in lymphoid tissues and is most strongly expressed in germinal center B cells. Methods Using gene expression profiling as well as immunohistochemistry with an anti-KLHL6 monoclonal antibody, we have characterized the expression of this molecule in normal and neoplastic tissues. Protein expression was evaluated in 1,058 hematopoietic neoplasms. Results Consistent with its discovery as a germinal center marker, KLHL6 was positive mainly in B-cell neoplasms of germinal center derivation, including 95% of follicular lymphomas (106/112). B-cell lymphomas of non-germinal center derivation were generally negative (0/33 chronic lymphocytic leukemias/small lymphocytic lymphomas, 3/49 marginal zone lymphomas, and 2/66 mantle cell lymphomas). Conclusions In addition to other germinal center markers, including BCL6, CD10, HGAL, and LMO2, KLHL6 immunohistochemistry may prove a useful adjunct in the diagnosis and future classification of B-cell lymphomas.

Summary Primary signet ring stromal tumor of the testis (PSRSTT) is an extremely rare tumor described only twice in the literature. Pancreatic-analogue solid pseudopapillary neoplasm (SPN) of the testis is a recently reported entity with morphological overlap with PSRSTT. We reviewed our files to find all cases of PSRSTT to better characterize this entity. We studied 13 cases of PSRSTTs using histological, immunohistochemical (IHC), and molecular genetic methods and compared the results with pancreatic SPN. Grossly, the size of PSRSTTs ranged from 0.5 to 2 cm (mean 1.1). Microscopically, PSRSTTs predominantly showed a proliferation of low-grade epithelioid cells containing characteristic cytoplasmic vacuole dislodging the nucleus (signet ring cells) separated by fibrous septa into trabeculae and nests. The immunoprofile was characterized by immunoreactivity for β -catenin, cyclin D1 (nuclear positivity for both antibodies), CD10, vimentin, galectin-3, claudin 7, α -1-antitrypsin, CD56, and neuron-specific enolase and negativity for chromogranin, inhibin, calretinin, SF-1, NANOG, OCT3/4, and SALL4. In some cases, the IHC panel was restricted because of a limited amount of tissue. Molecular genetic analysis revealed mutations within exon 3 of the CTNNB1 encoding β -catenin in all analyzable cases. Based on histological similarities between pancreatic SPN and PSRSTT and their identical IHC and molecular genetic features, we assume that both neoplasms share the same pathogenesis, and thus, PSRSTT can be considered as a testicular analogue of pancreatic SPN.

The diagnosis of marginal zone lymphomas (MZL) is challenged by the lack of specific markers that distinguish them from other low-grade non-Hodgkin B-cell lymphomas. Myeloid cell nuclear differentiation antigen (MNDA) is a nuclear protein that labels myelomonocytic cells as well as B lymphocytes that localize to the marginal zone areas of splenic white pulp. We evaluated MNDA expression in a large series of B-cell lymphomas to assess the sensitivity and specificity of this antigen for the characterization of MZL. A total of 440 tissue sections containing extramedullary B-cell lymphomas and 216 bone marrow biopsies containing atypical or neoplastic lymphoid infiltrates were stained for MNDA by immunohistochemistry. Among the extramedullary lymphoma cases, approximately 67% of nodal MZL, 61% of extranodal MZL, and 24% of splenic MZL expressed MNDA. MNDA was also infrequently expressed in other B-cell neoplasms including mantle cell lymphoma (6%), chronic lymphocytic leukemia/small lymphocytic lymphoma (13%), follicular lymphoma (FL) (4%), lymphoplasmacytic lymphoma (25%), and diffuse large B-cell lymphoma (3%). In contrast, MNDA was only expressed in 2.3% of all bone marrow biopsies involved by lymphoid infiltrates, including 2 cases of FL and one case of MZL. Collectively, these data support the inclusion of MNDA in the diagnostic evaluation of extramedullary B-cell lymphomas, particularly those in which the differential diagnosis is between low-grade FL and MZL.

NUT carcinoma (NC) is a rare malignant neoplasm usually located in the midline, including the upper aerodigestive tract. NC is an aggressive and highly lethal type of carcinoma. It is defined by the rearrangement of the nuclear protein in the testis (NUT) gene on chromosome 15q14. In most cases, the NUT is involved in a balanced translocation with the BRD4 gene on chromosome 19p13.1, an event that creates a BRD4-NUT fusion gene. The relationship between the human papillomavirus (HPV), p16, and upper aerodigestive tract cancer has been long postulated. In this study, we evaluated the relationship of the p16 expression in 4 cases of NCs and its eventual association with HPV. All 4 cases presented typical histopathologic findings with nuclear positivity of the NUT protein and strong expression for p16. None of these cases, however, showed an association with HPV evaluated by polymerase chain reaction. Despite the expression of p16, this negative result for HPV indicates that HPV infection probably does not play a role in the pathogenesis of NC.

Angiosarcomas are rare aggressive neoplasms of vascular endothelial origin with a high metastatic rate and poor prognosis. Involvement of the bone marrow by the angiosarcoma is exceedingly uncommon, and there have only been a few cases reported in the literature to date. Clinical manifestations and common laboratory findings of bone marrow involvement can mimic other more common bone marrow-replacing neoplasias such as lymphomas and acute leukemia. A definitive diagnosis is difficult to make from cytologic material, probably due to an associated bone marrow fibrosis, and requires bone marrow trephine biopsy with an immunohistochemical profile. Here we had the opportunity to study a case of metastatic angiosarcoma with positive cytologic findings and an unusual presentation that challenged its primary diagnosis.

Purpose Breast implant–associated anaplastic large-cell lymphoma (ALCL) is a recently described clinicopathologic entity that usually presents as an effusion-associated fibrous capsule surrounding an implant. Less frequently, it presents as a mass. The natural history of this disease and long-term outcomes are unknown. Patients and Methods We reviewed the literature for all published cases of breast implant–associated ALCL from 1997 to December 2012 and contacted corresponding authors to update clinical follow-up. Results The median overall survival (OS) for 60 patients was 12 years (median follow-up, 2 years; range, 0-14 years). Capsulectomy and implant removal was performed on 56 of 60 patients (93%). Therapeutic data were available for 55 patients: 39 patients (78%) received systemic chemotherapy, and of the 16 patients (28%) who did not receive chemotherapy, 12 patients opted for watchful waiting and four patients received radiation therapy alone. Thirty-nine (93%) of 42 patients with disease confined by the fibrous capsule achieved complete remission, compared with complete remission in 13 (72%) of 18 patients with a tumor mass. Patients with a breast mass had worse OS and progression-free survival (PFS; P = .052 and P = .03, respectively). The OS or PFS were similar between patients who received and did not receive chemotherapy (P = .44 and P = .28, respectively). Conclusion Most patients with breast implant–associated ALCL who had disease confined within the fibrous capsule achieved complete remission. Proper management for these patients may be limited to capsulectomy and implant removal. Patients who present with a mass have a more aggressive clinical course that may be fatal, justifying cytotoxic chemotherapy in addition to removal of implants.