The 1000 Mitoses Project: A Consensus-Based International Collaborative Study on Mitotic Figures Classification.

Introduction. The identification of mitotic figures is essential for the diagnosis, grading, and classification of various different tumors. Despite its importance, there is a paucity of literature reporting the consistency in interpreting mitotic figures among pathologists. This study leverages publicly accessible datasets and social media to recruit an international group of pathologists to score an image database of more than 1000 mitotic figures collectively. Materials and Methods. Pathologists were instructed to randomly select a digital slide from The Cancer Genome Atlas (TCGA) datasets and annotate 10-20 mitotic figures within a 2 mm2 area. The first 1010 submitted mitotic figures were used to create an image dataset, with each figure transformed into an individual tile at 40x magnification. The dataset was redistributed to all pathologists to review and determine whether each tile constituted a mitotic figure. Results. Overall pathologists had a median agreement rate of 80.2% (range 42.0%-95.7%). Individual mitotic figure tiles had a median agreement rate of 87.1% and a fair inter-rater agreement across all tiles (kappa = 0.284). Mitotic figures in prometaphase had lower percentage agreement rates compared to other phases of mitosis. Conclusion. This dataset stands as the largest international consensus study for mitotic figures to date and can be utilized as a training set for future studies. The agreement range reflects a spectrum of criteria that pathologists use to decide what constitutes a mitotic figure, which may have potential implications in tumor diagnostics and clinical management.

Metastatic solid tumors to the testis: a clinicopathologic evaluation of 157 cases from an international collaboration.

To elucidate the spectrum of metastatic solid tumors to the testis and their clinicopathologic features. The databases and files of 26 pathology departments from 9 countries on 3 continents were surveyed to identify metastatic solid tumors to the testis and to characterize their clinicopathologic features in detail. We compiled a series of 157 cases of metastatic solid tumors that secondarily involved the testis. The mean patient age at diagnosis was 64 years (range, 12-93 years). Most patients (127/144; 88%) had clinical manifestation of the disease, with testicular mass/nodule (89/127; 70%) being the most common finding. The main mechanism of testicular involvement was metastasis in 154/157 (98%) cases. Bilateral testicular involvement was present in 12/157 (8%) patients. Concurrent or prior extratesticular metastases were present in 78/101 (77%) patients. The diagnosis was made mainly in orchiectomy specimens (150/157; 95%). Different types of carcinomas (138/157; 87%), most commonly adenocarcinoma (72/157; 46%), were the most common malignancies. The most common primary carcinomas included prostatic (51/149; 34%), renal (29/149; 20%), and colorectal (13/149; 9%). Intratubular growth was identified in 13/124 (11%) cases and paratesticular involvement was found in 73/152 (48%) cases. In patients with available follow-up (110/157; 70%), more than half (58/110; 53%) died of disease. In this largest series compiled to date, we found that most secondary tumors of the testis represent metastases from the genitourinary and gastrointestinal tract carcinomas and typically occur in the setting of disseminated disease.

Low-grade oncocytic renal tumor (LOT): mutations in mTOR pathway genes and low expression of FOXI1.

Low-grade oncocytic renal tumor (LOT) is an emerging provisional entity, described as rare solid renal oncocytic/eosinophilic tumor sharing diffuse CK7 and negative CD117 immunoprofile. The links between LOT and other eosinophilic chromophobe like-renal cell carcinomas (RCC) are currently discussed. We sequenced tumoral DNA with a next generation sequencing panel for kidney cancer and carried out immunohistochemical analyses with CK7, CD117, SDHB, 4EBP1-P, S6K-P, and FOXI1 antibodies in a series of ten cases of LOT (9 females, 1 male; mean age at surgery: 66 years, 42.3 to 83.4) retrospectively diagnosed from a cohort of 272 tumors initially classified as chromophobe RCC (CHRCC). All LOT were single, without known hereditary predisposition, classified stage pT1 (70%), pT2 (20%) or pT3a (10%). Morphological features were similar to previous descriptions and clinical behavior was indolent for the six cases with available follow-up. We identified genetic variations in mTOR pathway related genes in 80% of cases, MTOR (7 cases) or TSC1 (1 case). Expression of FOXI1 was absent in all cases. In 9 LOT, 4EBP1-P and S6K-P were overexpressed, suggesting mTOR pathway activation.Our data highlights the major role of mTOR pathway in tumorigenesis of LOT mostly due to activating MTOR gene variations. Absence of FOXI1 expression is a strong argument to distinguish LOT from eosinophilic CHRCC and to bring them closer to other recently described FOXI1 negative eosinophilic-CHRCC like with MTOR/TSC mutations. Altogether, our data argue to consider LOT as a distinct entity with a favorable clinical outcome. However, in case of metastasis, an accurate diagnosis of LOT would be essential for the patient's management and could allow targeted therapy.

Adrenal ganglioneuromas: a retrospective multicentric study of 104 cases from the COMETE network.

OBJECTIVE: Adrenal ganglioneuromas are rare, differentiated, neuroblastic tumors that originate from the peripheral sympathetic nervous system. Because of their rarity, information is limited, derived from small cases series. Our objective was to characterize this tumor and provide help for its management. METHODS: A retrospective multicenter analysis of adrenal ganglioneuromas from 20 French centers belonging to the COMETE network and one Belgian center. RESULTS: Among the 104 cases identified, 59.6% were women (n = 62/104), median age at diagnosis was 29 years, with 24 pediatric cases. 60.6% (n = 63/104) were incidentalomas. Ganglioneuromas were non-secreting tumors in 90.8% of cases (n = 89/98), whereas the preoperative hormonal evaluation was indeterminate for 9.2% of patients (n = 9/98). CT imaging, performed on 96 patients, revealed large tumors (median diameter of 50 mm) with a non-contrast density > 10 Hounsfield units in 98.1% (n = 52/53) and calcifications in 64.6% of cases (n = 31/48). Increased uptake on 123I-MIBG scintigraphy and 18F-FDG-PET/CT was observed in 26.7% (n = 8/30) and 42.2% (n = 19/45) of the tumors, respectively. All 104 patients underwent surgery. No recurrence was observed among the 42 patients who had an imaging follow-up (mean 29.6 months, median 18 months (4-156)). CONCLUSION: Adrenal ganglioneuromas are large tumors, mostly nonfunctioning, without benign imaging features. Although the duration of follow-up was limited in our series, no recurrence was identified. A review of the literature confirms the absence of postoperative recurrence. Based on all available data, in the absence of special circumstances (genetic form, uncertain histological diagnosis), long-term follow-up is not necessary after complete surgery for patients with an adrenal ganglioneuroma.

Renal cell carcinoma with leiomyomatous stroma in tuberous sclerosis complex: a distinct entity.

Renal cell carcinoma with leiomyomatous stroma (RCCLS) is an emerging entity frequently associated with tuberous sclerosis complex (TSC). We described herein a series of RCCLS in TSC patients at pathological and cytogenetic levels. Three male patients with TSC and RCCLS were identified between 2000 and 2019 at the University Hospital of Rennes. Histologically, the architecture was tubulo-papillary with thick bundles of smooth muscle cells. The tumor cells showed clear cytoplasm with eosinophilic globules. The immunohistochemical profile was identical with an intense positivity of CK7, CAIX, and CD10 and a heterogeneous positivity of CK20. SDHB was low but positive and TFE3 was not expressed. Comparative genomic hybridization (CGH) did not show any quantitative chromosome abnormality. No recurrence was observed with a median follow-up of 4 years. RCCLS in TSC patients has morphological, immunohistochemical, and cytogenetic distinct features that could constitute a distinct entity and a sentinel manifestation for the diagnosis of TSC.

MET alterations in biphasic squamoid alveolar papillary renal cell carcinomas and clinicopathological features.

Biphasic squamoid alveolar papillary renal cell carcinoma (BSA-PRCC) is a recently studied lesion considered a morphologic variant of papillary renal cell carcinoma (RCC), more closely related to type 1. Considering the role of proto-oncogene MET in both sporadic type 1 papillary RCC and hereditary papillary RCC, we aimed to explore the role of MET activation in the oncogenesis of BSA-PRCC. We identified 17 patients with either unique (n = 14) or multiple (n = 3) BSA-PRCC, all localized, and performed an integrative analysis of MET status in 18 formalin-fixed paraffin-embedded tumors combining next-generation sequencing analysis, fluorescent in situ hybridization and immunohistochemistry. Trisomy 7 was found in 86% of tumors (14/16) without MET amplification at 7q31 (15/15). A pathogenic MET genetic variant was identified in 60% (9/15) of cases, at the germline level in 57% (4/7) of tested patients or at the somatic level (5/11). MET expression was observed in all tumors with a higher value of combined score in large cells (mean 97%, range 80-100%) than in small cells (mean 74%, range 10-100%) and was lower in two cases without MET copy number gain. In conclusion, our study provides additional evidence to consider biphasic squamoid alveolar papillary RCC as a morphological variant of type 1 papillary renal RCC. Our data strongly suggest that MET represents a major oncogenic driver gene in BSA-PRCC, harboring a higher frequency of MET mutation that encourages to further explore the benefice of anti-MET targeted therapies for aggressive BSA-PRCC.

Germline DLST Variants Promote Epigenetic Modifications in Pheochromocytoma-Paraganglioma.

CONTEXT: Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumors in which altered central metabolism appears to be a major driver of tumorigenesis, and many PPGL genes encode proteins involved in the tricarboxylic acid (TCA) cycle. OBJECTIVE/DESIGN: While about 40% of PPGL cases carry a variant in a known gene, many cases remain unexplained. In patients with unexplained PPGL showing clear evidence of a familial burden or multiple tumors, we aimed to identify causative factors using genetic analysis of patient DNA and functional analyses of identified DNA variants in patient tumor material and engineered cell lines. PATIENTS AND SETTING: Patients with a likely familial cancer burden of pheochromocytomas and/or paragangliomas and under investigation in a clinical genetic and clinical research setting in university hospitals. RESULTS: While investigating unexplained PPGL cases, we identified a novel variant, c.1151C>T, p.(Pro384Leu), in exon 14 of the gene encoding dihydrolipoamide S-succinyltransferase (DLST), a component of the multi-enzyme complex 2-oxoglutarate dehydrogenase. Targeted sequence analysis of further unexplained cases identified a patient carrying a tumor with compound heterozygous variants in DLST, consisting of a germline variant, c.1121G>A, p.(Gly374Glu), together with a somatic missense variant identified in tumor DNA, c.1147A>G, p.(Thr383Ala), both located in exon 14. Using a range of in silico and functional assays we show that these variants are predicted to be pathogenic, profoundly impact enzyme activity, and result in DNA hypermethylation. CONCLUSIONS: The identification and functional analysis of these DLST variants further validates DLST as an additional PPGL gene involved in the TCA cycle.

HPV Detection in Head and Neck Squamous Cell Carcinomas: What Is the Issue?

Besides classic tobacco and alcohol risk factors, human papillomavirus (HPV) plays a role in the development of a subset of head and neck squamous cell carcinomas (HNSCCs), and notably oropharynx squamous cell carcinomas (OPSCCs). HPV-induced OPSCCs have a different biological behavior and a better prognosis compared to non-HPV-induced OPSCCs and the eighth-edition TNM classification now separates these two entities. Therefore, determining the HPV status of patients with OPSCC is now essential for treatment, prognosis, and development of clinical trials. In this review, after reminding essential steps of HPV implication in the cell cycle, we describe the existing tools that are currently feasible in routine practice according to facilities available in health structures, with their benefits and drawbacks: HPV PCR, E6/E7 mRNA RT-PCR, E6/E7 mRNA in situ hybridization, HPV DNA in situ hybridization, and P16 immunochemistry. Besides these traditional HPV detection tools, novel diagnostic approaches are being evaluated for HPV-induced OPSCC "ultrastaging." E6 humoral response and ddPCR-detecting HPVct DNA are two techniques performed on blood and are therefore non-invasive. Baseline E6 humoral levels could have a prognostic value, and HPVct DNA could be helpful for HPV OPSCC recurrence monitoring. At last, next-generation sequencing (NGS)-based "capture HPV" is a technique feasible on biopsies and circulating DNA material. It helps characterize HPV integration status and sites, and it could define prognostic subgroups in HPV-induced OPSCC. These novel precision detection tools could be further integrated in the care of patients with HPV-induced OPSCC.

Interpretable multimodal deep learning for real-time pan-tissue pan-disease pathology search on social media.

Pathologists are responsible for rapidly providing a diagnosis on critical health issues. Challenging cases benefit from additional opinions of pathologist colleagues. In addition to on-site colleagues, there is an active worldwide community of pathologists on social media for complementary opinions. Such access to pathologists worldwide has the capacity to improve diagnostic accuracy and generate broader consensus on next steps in patient care. From Twitter we curate 13,626 images from 6,351 tweets from 25 pathologists from 13 countries. We supplement the Twitter data with 113,161 images from 1,074,484 PubMed articles. We develop machine learning and deep learning models to (i) accurately identify histopathology stains, (ii) discriminate between tissues, and (iii) differentiate disease states. Area Under Receiver Operating Characteristic (AUROC) is 0.805-0.996 for these tasks. We repurpose the disease classifier to search for similar disease states given an image and clinical covariates. We report precision@k = 1 = 0.7618 ± 0.0018 (chance 0.397 ± 0.004, mean ±stdev ). The classifiers find that texture and tissue are important clinico-visual features of disease. Deep features trained only on natural images (e.g., cats and dogs) substantially improved search performance, while pathology-specific deep features and cell nuclei features further improved search to a lesser extent. We implement a social media bot (@pathobot on Twitter) to use the trained classifiers to aid pathologists in obtaining real-time feedback on challenging cases. If a social media post containing pathology text and images mentions the bot, the bot generates quantitative predictions of disease state (normal/artifact/infection/injury/nontumor, preneoplastic/benign/low-grade-malignant-potential, or malignant) and lists similar cases across social media and PubMed. Our project has become a globally distributed expert system that facilitates pathological diagnosis and brings expertise to underserved regions or hospitals with less expertise in a particular disease. This is the first pan-tissue pan-disease (i.e., from infection to malignancy) method for prediction and search on social media, and the first pathology study prospectively tested in public on social media. We will share data through http://pathobotology.org . We expect our project to cultivate a more connected world of physicians and improve patient care worldwide.

[Hereditary kidney cancers: The pathologist's view in 2020]. / Les cancers du rein héréditaires vus par le pathologiste en 2020.

Hereditary predispositions to adult kidney tumors involve around 5% of tumors and include a dozen of autosomal dominant syndromes. The most frequent tumors encountered in these setting are clear cell renal cell carcinomas, papillary renal cell carcinomas, chromophobe renal cell carcinomas and angiomyolipomas. Their detection is essential in order to adapt individual care and perform genetic screening of at-risk relatives, especially in the national french network PREDIR, labeled by the National Cancer Institute and dedicated to hereditary predispositions to kidney tumors. Targeted genetic analysis, which was guided in particular by the renal tumor subtype, has recently evolved into genetic analysis using panels of genes. Pathologist contribution's remains however central in the diagnosis of hereditary forms since we currently have immunohistochemical biomarkers that allow us to diagnose two specifically hereditary entities: hereditary leiomyomatosis and renal cell carcinoma associated-renal cell carcinoma, associated with a loss of fumarate hydratase and succinate dehydrogenase-deficient renal cell carcinoma associated with a loss of succinate deshydrogenase B expression. These diagnoses must however be confirmed by the identification of pathogenic germline variation in the corresponding genes. Improvement of kidney tumors characterization has also lead to identify new subtypes, expanding the algorithm of renal tumors associated with hereditary setting. Here we aim to review all subtypes of adult renal tumors encountered in predisposition syndromes.

The Microenvironment of Head and Neck Cancers: Papillomavirus Involvement and Potential Impact of Immunomodulatory Treatments.

Cancer progression can be understood as the result of deregulation of tumors' immune microenvironments. Recent studies of the alterations of microenvironments highlight their significant influence on the prognosis of patients with head and neck squamous cell carcinoma (HNSCC). It is necessary to better characterize tumor-infiltrating lymphocytes by focusing, in particular, on the tumor escape mechanisms from immune surveillance. One of the best described tumor immune system evasion mechanisms is the expression of co-stimulation molecules that constitute so-called "immune checkpoints". These molecules regulate the immune response by either activating or inhibiting its effects. The programmed cell death 1 (PD-1) surface protein is an inhibitory co-stimulation molecule that induces exhaustion of activated T-lymphocytes (TLs, T cells) through binding with its ligands, PD-L1 and PD-L2. Half of HNSCCs exhibit PD-L1 expression with higher expression identified in human papillomavirus (HPV) positive tumors. Numerous studies have shown differences between the microenvironments of HPV+ and HPV- cancers. Notably, infiltrations of exhausted CD4+ PD1+ and CD8+ PD1+ T cells are far higher in the microenvironment of HPV+ tumors. The FDA has approved the use of molecules that target PD-1 for the treatment of HNSCC. The first results of clinical trials with anti-PD-1 blockers in HNSCC show improved patient survival, particularly long-term survival without recurrence. However, discordant results were sometimes observed, and improvements in defining cellular predictive markers are necessary. With the development of immunotherapies, pathologists play a role in the selection of patients who are eligible for specific treatments and assessment of their prognosis in greater detail. An automated, quantitative in situ imaging system that integrates both multispectral imaging and automated slide scanning could be developed in pathology laboratories. The evaluation of PD-L1 expression has only been used to stratify the administration of first-line immunotherapy. The validation of these tests and their routine interpretation is essential. No specific recommendation is adopted for HPV+ HNSCC.

Clear Cell Papillary Renal Cell Carcinoma: A Recent Entity With Distinct Imaging Patterns.

OBJECTIVE. Clear cell papillary renal cell carcinoma (RCC), an entity with strikingly indolent behavior, recently was added to the World Health Organization classification of renal tumors and represents the fourth most common histologic type of renal cell carcinoma. This article aims to describe the imaging features of clear cell papillary RCC along with its clinical and pathologic characteristics. MATERIALS AND METHODS. This retrospective study consisted of 27 patients with 44 clear cell papillary RCC tumors. The inclusion criteria were a pathologically proven clear cell papillary RCC and the availability of preoperative imaging including at least CT or MRI. Two experienced radiologists performed the imaging analysis independently. RESULTS. Patients (mean age, 62 years old) presented with renal failure in 26% of cases, and four had a tumor-predisposing disease. Multiple clear cell papillary RCC tumors occurred in 5 of the 27 patients. Two imaging patterns were recognizable. Solid clear cell papillary RCC (n = 23, 52%) presented as heterogeneous tumors with minor cystic changes (74%) and rarely exhibited calcifications (10%). All solid tumors showed hyperintensity on T2-weighted images compared with renal cortex and maximal enhancement on corticomedullary phase with a delayed washout. Cystic clear cell papillary RCC (n = 21, 48%) were classified as Bosniak IV (57%), III (33%), or IIF (10%), with a predominant unilocular pattern (76%). Pathologic stage according to TNM classification was mostly pT1a and low grade on nucleolar grade. All patients were alive at the date of last follow-up after treatment with no metastasis or recurrence. CONCLUSION. Clear cell papillary RCC exhibits two imaging patterns including cystic and solid in almost equal proportion. Imaging characteristics of solid clear cell papillary RCC including high signal T2 intensity and early arterial enhancement are unexpectedly distinct from papillary RCC and very similar to clear cell RCC.

[Pathologist versus social media: A survival guide]. / Le pathologiste et les réseaux sociaux : mode d'emploi.

Social networks have changed the communication tools among healthcare professionals, enabling instantaneous and globalized sharing and monitoring of information. While more and more pathologists are taking advantage of these tools, some do not yet know them well, or have concerns about their use. These platforms have many advantages and the potential risks can be minimized by appropriate use. A pathologist community is very active, especially on Twitter and Facebook. They share and discuss interesting cases, communicate around our specialty or simply strengthen links between pathologists around the world. Professional organizations and pathology journals are also present. This article aims to present social networks, their pros and cons and to give some good practice tips and examples of uses of the 2 main social networks used in pathology: Facebook and Twitter.