Case report: A novel somatic SDHB variant in a patient with bladder paraganglioma.

Background: Paragangliomas (PGL) are rare neuroendocrine tumors derived from the autonomic nervous system paraganglia. Urinary bladder paragangliomas (UBPGL) originate from the sympathetic neurons of the urinary bladder wall and represent 0.7% of all paragangliomas and <0.05% of all bladder tumors. PGL and UBPGL can be associated with SDHB, SDHD, NF1, and VHL gene variants, with the most common germline alterations found in SDHB and VHL. Case report: We report a case of a 42-year-old woman who presented with menorrhagia/hematuria, uterine leiomyomas, as well as cardiac and bladder masses. The cardiac mass was favored to be a myxoma based on clinical findings, while the bladder mass was diagnosed as UBPGL. A novel SDHB mutation (c.642G>A, p Q214Q), detected in the UBPGL, was proven to be somatic. Although this variant was seemingly synonymous, it was predicted to have a loss of function due to the splice site effect, which was further supported by the immunohistochemical loss of SDHB. Conclusion: This case highlights the challenges of diagnosing an extremely rare entity, bladder paraganglioma, with an emphasis on the multidisciplinary approach to navigate various clinical and imaging findings that may initially be misleading. In addition, a novel loss of function SDHB variant that could have been overlooked as a synonymous variant is herein reported, while also illustrating the importance of both germline and somatic mutation testing.

Molecular Pathology of Ovarian Epithelial Neoplasms: Predictive, Prognostic, and Emerging Biomarkers.

This review focuses on the diagnostic, prognostic, and predictive molecular biomarkers in ovarian epithelial neoplasms in the context of their morphologic classifications. Currently, most clinically actionable molecular findings are reported in high-grade serous carcinomas; however, the data on less common tumor types are rapidly accelerating. Overall, the advances in genomic knowledge over the last decade highlight the significance of integrating molecular findings with morphology in ovarian epithelial tumors for a wide-range of clinical applications, from assistance in diagnosis to predicting response to therapy.

Uterine Inflammatory Myofibroblastic Tumors: p16 as a Surrogate for CDKN2A Deletion and Predictor of Aggressive Behavior.

Uterine inflammatory myofibroblastic tumors (IMTs) are rare mesenchymal neoplasms of uncertain malignant potential. Aside from the recently described risk stratification score, which has not been validated by other studies, and rare reports of aberrant p16 expression in malignant tumors, there are no criteria to reliably predict behavior. Herein, we evaluated the clinicopathologic features and p16 expression patterns in 30 IMTs, with genomic profiling performed in a subset (13 malignant, 3 benign). Fifteen patients had malignant IMTs, defined by extrauterine disease at diagnosis (n=5) or recurrence (n=10; median: 24 mo). Patients ranged from 8 to 65 (median: 51) years and tumors from 6 to 22 (median: 12.5) cm. In primary tumors (n=13), infiltrative borders were noted in 10, moderate/severe cytologic atypia in 9, tumor cell necrosis in 7, and lymphovascular invasion in 6, while mitoses ranged from 0 to 21 (median: 7) per 10 high-power fields. In contrast, 15 patients with benign IMTs ranged from 28 to 65 (median: 44) years, with follow-up of 18 to 114 (median: 41) months. Tumors ranged from 1.9 to 8.5 (median: 5.5) cm, 2 demonstrated infiltrative borders, and 1 had moderate cytologic atypia. No other high-risk histologic features were observed. Application of the previously described clinicopathologic risk stratification score in all primary IMTs with complete data (n=18) classified 8 as high-risk (all malignant), 8 as intermediate-risk (3 malignant, 5 benign), and 2 as low-risk (benign). p16 was aberrant in all malignant IMTs, with <1% expression noted in 10, overexpression (>90%) in 4, and subclonal loss in 1; all benign tumors had patchy staining (20% to 80%; median 50%). Molecular analysis detected CDKN2A deletions in 8 of 9 tumors with <1% p16 expression, while the other harbored a TERT promoter mutation. TERT promoter mutations were also identified in 2 of 3 IMTs with p16 overexpression. Neither of these alterations was detected in the 3 sequenced benign IMTs. Thus, we recommend performing p16 on all uterine IMTs, which, combined with the risk stratification score, is a promising and cost-effective tool for predicting CDKN2A status and outcome in these patients. It may be particularly useful for tumors with incomplete information for risk stratification (ie, morcellated tumors) and for further stratifying intermediate-risk IMTs when sequencing is unavailable.

Extrauterine epithelioid trophoblastic tumour and its somatic carcinoma mimics: short tandem repeat genotyping meets the diagnostic challenges.

AIMS: While epithelioid trophoblastic tumour (ETT) primarily arises from the uterus, cases have been increasingly documented at extrauterine sites, originating from an ectopic gestation or presenting as a metastatic tumour, leading to the major differential diagnosis of somatic carcinoma with trophoblastic differentiation. The precise separation of a gestational trophoblastic tumour from its somatic carcinoma mimics is highly relevant and crucial for patient management and prognosis. METHODS AND RESULTS: We summarise the clinicopathological and molecular features of four challenging epithelioid malignancies presenting at extrauterine sites, with ETT as the main differential diagnosis. All four tumours demonstrated histological and immunohistochemical features overlapping between a somatic carcinoma and an ETT, combined with inconclusive clinical and imaging findings. Serum beta-hCG elevation was documented in two cases. Short tandem repeat (STR) genotyping was performed and was informative in all cases. The presence of a unique paternal allelic pattern in the tumour tissue confirmed the diagnosis of ETT in two cases with an initial consideration of either somatic carcinoma or suspicion of a gestational trophoblastic tumour. The presence of matching genetic profile with the patient's paired normal tissue was seen in two other cases (both initially considered as ETT), confirming their somatic origin, including one metastatic triple-negative breast carcinoma and one primary lung carcinoma. CONCLUSIONS: Diagnostic separation of ETT at an extrauterine site from its somatic carcinoma mimics can be difficult at the histological and immunohistochemical levels. STR genotyping offers a robust ancillary tool that precisely separates ETT from somatic carcinomas with trophoblastic differentiation.

Systematic identification of anticancer drug targets reveals a nucleus-to-mitochondria ROS-sensing pathway.

Multiple anticancer drugs have been proposed to cause cell death, in part, by increasing the steady-state levels of cellular reactive oxygen species (ROS). However, for most of these drugs, exactly how the resultant ROS function and are sensed is poorly understood. It remains unclear which proteins the ROS modify and their roles in drug sensitivity/resistance. To answer these questions, we examined 11 anticancer drugs with an integrated proteogenomic approach identifying not only many unique targets but also shared ones-including ribosomal components, suggesting common mechanisms by which drugs regulate translation. We focus on CHK1 that we find is a nuclear H2O2 sensor that launches a cellular program to dampen ROS. CHK1 phosphorylates the mitochondrial DNA-binding protein SSBP1 to prevent its mitochondrial localization, which in turn decreases nuclear H2O2. Our results reveal a druggable nucleus-to-mitochondria ROS-sensing pathway-required to resolve nuclear H2O2 accumulation and mediate resistance to platinum-based agents in ovarian cancers.

Update on Ovarian Sex Cord-Stromal Tumors.

This article focuses on the recent advances in ovarian sex cord-stromal tumors, predominantly in the setting of their molecular underpinnings. The integration of genetic information with morphologic and immunohistochemical findings in this rare subset of tumors is of clinical significance from refining the diagnostic and prognostic stratifications to genetic counseling.

Midline brain hamartomatous lesions in fibrodysplasia ossificans progressiva with ACVR1 mutations.

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder characterized by extensive heterotopic ossification of soft tissue structures leading to severe limitations in movement. FOP is caused by a germline mutation in the activating receptor type IA (ACVR1) gene. Worrisome is the fact that up to a third of diffuse intrinsic pontine gliomas (DIPG) also harbor the same point mutation in ACVR1. Radiological reports of central nervous system (CNS) involvement by FOP have described brainstem masses; however, the literature on the histopathology or pathogenesis of these lesions is scant. Here we present detailed neuropathologic findings of a brainstem mass in a patient with FOP and suggest that the tumor is hamartomatous in nature. This report, along with a literature review of radiographic and laboratory data, offers support for the idea that the ACVR1 mutation may incite CNS proliferation, predominantly in the brainstem, but is probably not an oncologic driver. These lesions may be seen at autopsy and are likely noncontributory to death.

Morphologic and Molecular Heterogeneity of Cervical Neuroendocrine Neoplasia: A Report of 14 Cases.

Neuroendocrine neoplasms (NENs) of the cervix are rare aggressive tumors associated with poor prognosis and only limited treatment options. Although there is some literature on molecular underpinnings of cervical small cell neuroendocrine carcinomas (SCNECs), detailed morphologic and associated molecular characteristics of cervical NENs remains to be elucidated. Herein, 14 NENs (SCNEC: 6, large cell neuroendocrine carcinoma [LCNEC]: 6, neuroendocrine tumor [NET]: 2), including 5 admixed with human papillomavirus (HPV)-associated adenocarcinoma (carcinoma admixed with neuroendocrine carcinoma) were analyzed. All except 3 SCNECs were HPV16/18 positive. TP53 (3) and/or RB1 (4) alterations (3 concurrent) were only seen in SCNECs (4/6) and were enriched in the HPV16/18-negative tumors. The other most common molecular changes in neuroendocrine carcinomas (NECs) overlapping with those reported in the literature for cervical carcinomas involved PI3K/MAPK pathway (4) and MYC (4) and were seen in both SCNECs and LCNECs. In contrast, the 2 NETs lacked any significant alterations. Two LCNECs admixed with adenocarcinoma had enough material to sequence separately each component. In both pathogenic alterations were shared between the 2 components, including ERBB2 amplification in one and an MSH6 mutation with MYC amplification in the other. Overall, these findings suggest that cervical HPV-associated NETs are genomically silent and high-grade NECs (regardless of small or large cell morphology) share molecular pathways with common cervical carcinomas as it has been reported in the endometrium and are different from NECs at other sites. Molecular analysis of these highly malignant neoplasms might inform the clinical management for potential therapeutic targets.

Molecular Detection of Oncogenic Gene Rearrangements.

Oncogenic gene rearrangements have been exponentially significant for clinical management of cancer, from diagnosis to therapy and disease monitoring. Testing algorithms should be created with caution, and sample type, accessibility to testing method, turnaround time, and economic aspects should be taken into consideration. Herein, different molecular technologies for detecting these gene rearrangements are discussed and the benefits and limitations of each method are highlighted.

Update on Ovarian Sex Cord-Stromal Tumors.

This article focuses on the recent advances in ovarian sex cord-stromal tumors, predominantly in the setting of their molecular underpinnings. The integration of genetic information with morphologic and immunohistochemical findings in this rare subset of tumors is of clinical significance from refining the diagnostic and prognostic stratifications to genetic counseling.

Low-grade Endometrial Stromal Sarcoma With Sex Cord-like Differentiation and PHF1-JAZF1 Fusion With Deletions: A Diagnostic Pitfall of JAZF1 FISH.

The molecular knowledge of endometrial stromal neoplasms has been rapidly increasing and is considered complementary to morphologic and immunohistochemical findings for better categorization of these tumors. The most common molecular alteration observed in low-grade endometrial stromal sarcomas is the JAZF1-SUZ12 fusion, whereas, low-grade endometrial stromal sarcoma with sex cord-like differentiation have been shown more commonly to have fusions involving PHF1. Herein, we present a low-grade endometrial stromal sarcoma with sex cord-like differentiation with a fluorescence in situ hybridization showing the apparent loss of one copy of JAZF1 5' and 3' signals, rather than the expected "break-apart" pattern seen in the setting of a JAZF1 fusion. The case was then further evaluated by chromosome microarray and RNA fusion analysis. Overall, the molecular findings supported a PHF1-JAZF1 fusion with deletions right before and after the JAZF1 locus, impairing probe binding and resulting in the unusual "deletion" pattern observed in the JAZF1 fluorescence in situ hybridization, which would not intuitively suggest a fusion involving JAZF1. This case illustrates the importance of integration of morphological and molecular findings as well as the limitations of fluorescence in situ hybridization in detecting fusions, particularly in the setting of more complex chromosomal alterations even though the fusion partners are well-known.

Uterine PEComas: correlation between melanocytic marker expression and TSC alterations/TFE3 fusions.

Uterine PEComas often present a diagnostic challenge as they share morphological and immunohistochemical features with smooth muscle tumors. Herein we evaluated a series of 19 uterine PEComas to compare the degree of melanocytic marker expression with their molecular profile. Patients ranged from 32-77 (median 48) years, with six tumors classified as malignant based on the modified gynecologic-specific prognostic algorithm. All patients with malignant PEComas were alive with disease or dead  of disease at last follow-up, while all those of uncertain malignant potential were alive and well (median follow-up, 47 months).Seventeen of 19 (89%) PEComas harbored either a TSC1 or TSC2 alteration. One of the two remaining tumors showed a TFE3 rearrangement, but the other lacked alterations in all genes evaluated. All showed at least focal (usually strong) positivity for HMB-45, with 15/19 (79%) having >50% expression, while the tumor lacking TSC or TFE3 alterations was strongly positive in 10% of cells. Melan-A and MiTF were each positive in 15/19 (79%) tumors, but staining extent and intensity were much more variable than HMB-45. Five of six (83%) malignant PEComas also harbored alterations in TP53, ATRX, or RB1, findings not identified in any tumors of uncertain malignant potential. One malignant PEComa was microsatellite-unstable/mismatch repair protein-deficient.In summary, TSC alterations/TFE3 fusions and diffuse (>50%) HMB-45 expression are characteristic of uterine PEComas. In morphologically ambiguous mesenchymal neoplasms with myomelanocytic differentiation, especially those with metastatic or recurrent disease, next-generation sequencing is recommended to evaluate for TSC alterations; as such, patients can be eligible for targeted therapy.

Hyperprogression of a mismatch repair-deficient colon cancer in a humanized mouse model following administration of immune checkpoint inhibitor pembrolizumab.

Immunotherapy is an established treatment modality in oncology. However, in addition to primary or acquired therapy resistance with immune checkpoint blockade (ICB), hyperprogressive disease (HPD) or hyperprogression (HP) with acceleration of tumor growth occurs in a subset of patients receiving ICB therapy. A validated and predictive animal model would help investigate HPD/HP to develop new approaches for this challenging clinical entity. Using human cytotoxic T-cell line TALL-104 injected intraperitoneally into immunodeficient NCRU-nude athymic mice bearing mismatch repair-deficient (MMR-d) human colon carcinoma HCT116 p53-null (but not wild-type p53) tumor xenograft, we observed accelerated tumor growth after PD-1 blockade with pembrolizumab administration. There was increased colon tumor cell proliferation as determined by immunohistochemical Ki67 staining of tumor sections. There was no increase in MDM2 or MDM4/MDMX in the p53-null HCT116 cells versus the wild-type p53-expressing isogenic tumor cells, suggesting the effects in this model may be MDM2 or MDM4/MDMX-independent. Human cytokine profiling revealed changes in IFN-γ, TRAIL-R2/TNFRSF10B, TRANCE/TNFSF11/RANK L, CCL2/JE/MCP-1, Chitinase 3-like 1, IL-4 and TNF-α. This represents a novel humanized HPD mouse model with a link to deficiency of the p53 pathway of tumor suppression in the setting of MMR-d. Our novel humanized preclinical TALL-104/p53-null HCT116 mouse model implicates p53-deficiency in an MMR-d tumor as a possible contributor to HPD/HP and may help with evaluating therapeutic strategies in cancer immunotherapy to extend clinical benefits of ICB's in a broader patient population.

Molecular Pathology of Ovarian Epithelial Neoplasms: Predictive, Prognostic, and Emerging Biomarkers.

This review focuses on the diagnostic, prognostic, and predictive molecular biomarkers in ovarian epithelial neoplasms in the context of their morphologic classifications. Currently, most clinically actionable molecular findings are reported in high-grade serous carcinomas; however, the data on less common tumor types are rapidly accelerating. Overall, the advances in genomic knowledge over the last decade highlight the significance of integrating molecular findings with morphology in ovarian epithelial tumors for a wide-range of clinical applications, from assistance in diagnosis to predicting response to therapy.

Locally Recurrent Secretory Carcinoma of the Breast with NTRK3 Gene Fusion.

Enhanced understanding of the molecular events underlying oncogenesis has led to the development of "tumor-agnostic" treatment strategies, which aim to target a tumor's genomic profile regardless of its anatomic site of origin. A classic example is the translocation resulting in an ETV6-NTRK3 gene fusion, a characteristic driver of a histologically diverse array of cancers. The chimeric ETV6-NTRK3 fusion protein elicits constitutive activation of the tropomyosin receptor kinase (TRK) C protein, leading to increased cell survival, growth, and proliferation. Two TRK inhibitors, larotrectinib and entrectinib, are currently approved for use in the metastatic setting for the treatment of advanced solid tumors harboring NTRK fusions. Here we report a rare case of recurrent secretory carcinoma of the breast (SCB) with NTRK3 gene fusion. Whereas most cases of SCB represent slow-growing tumors with favorable outcomes, the case detailed here is the first to the authors' knowledge of recurrence within 1 year of surgery. We review the molecular findings and potential clinical significance. KEY POINTS: The translocation resulting in the ETV6-NTRK3 gene fusion is a known oncogenic driver characteristic of secretory carcinoma of the breast (SCB). Whereas most cases of SCB represent slow-growing tumors with favorable outcomes, the case here with ETV6-NTRK3 gene fusion had local recurrence within 1 year of surgery. Two tropomyosin receptor kinase (TRK) inhibitors, larotrectinib and entrectinib, are approved to treat NTRK fusion-positive tumors, demonstrating sustained high overall response rates in the metastatic setting. Approval of TRK inhibitors necessitates optimization of NTRK fusion detection assays, including detection with liquid biopsies.

Embryonal rhabdomyosarcoma of the uterine corpus: a clinicopathological and molecular analysis of 21 cases highlighting a frequent association with DICER1 mutations.

Herein we evaluated a series of 21 embryonal rhabdomyosarcomas of the uterine corpus (ucERMS), a rare neoplasm, to characterize their morphology, genomics, and behavior. Patients ranged from 27 to 73 (median 52) years and tumors from 4 to 15 (median 9) cm, with extrauterine disease noted in two. Follow-up (median 16 months) was available for 14/21 patients; nine were alive and well, four died of disease, and one died from other causes. Most tumors (16/21) showed predominantly classic morphology, comprised of alternating hyper- and hypocellular areas of primitive small cells and differentiating rhabdomyoblasts in a loose myxoid/edematous stroma. A cambium layer was noted in all; seven had heterologous elements (six with fetal-type cartilage) and eight displayed focal anaplasia. The remaining five neoplasms showed only a minor component (≤20%) of classic morphology, with anaplasia noted in four and tumor cell necrosis in three. The most frequent mutations detected were in DICER1 (14/21), TP53 (7/20), PI3K/AKT/mTOR pathway (7/20), and KRAS/NRAS (5/20). Copy-number alterations were present in 10/19 tumors. Overall, 8/14 DICER1-associated ucERMS showed concurrent loss of function and hotspot mutations in DICER1, which is a feature more likely to be seen in tumors associated with DICER1 syndrome. Germline data were available for two patients, both DICER1 wild type (one with concurrent loss of function and hotspot alterations). DICER1-associated ucERMS were more likely to show a classic histological appearance including heterologous elements than DICER1-independent tumors. No differences in survival were noted between the two groups, but both patients with extrauterine disease at diagnosis and two with recurrences died from disease. As no patients had a known personal or family history of DICER1 syndrome, we favor most DICER1-associated ucERMS to be sporadic.