Echoendoscopic ultrasound pancreatic adenocarcinoma diagnosis and theranostic approach: should KRAS mutation research be recommended in everyday practice?

Background: The impact of KRAS mutation testing on pancreatic ductal adenocarcinoma (PDAC) samples by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for reducing the need to repeat EUS-FNA has been demonstrated. Such testing however is not part of standard practice for endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB). Objectives: We aim to analyse the proportion of non-contributive samples by EUS-FNB and to evaluate the impact of KRAS mutation testing on the diagnosis, theranostics and survival. Design: In this retrospective study, the impact on diagnosis and survival of KRAS testing for contributive and non-contributive samples by EUS-FNB was analysed. Methods: The EUS-FNB samples, combined with KRAS testing using the Idylla® technique on liquid-based cytology from patients with PDAC between February 2019 and May 2023, were retrospectively reviewed. The cytology results were classified according to the guidelines of the World Health Organization System for Reporting Pancreaticobiliary Cytopathology (WHOSRPC). Results: A total of 85 EUS-FNB specimens were reviewed. In all, 25 EUS-FNB samples did not lead to a formal diagnosis of PDAC according to the WHOSRPC (30.2%). Out of these 25, 11 (44%) could have been considered positive for a PDAC diagnosis thanks to the KRAS mutation test without carrying out further diagnosis procedures. The sensitivity of KRAS mutation testing using the Idylla technique was 98.6%. According to the available data, survival rates were not statistically different depending on the type of mutation. Conclusion: KRAS mutation testing on liquid-based cytology using the Idylla or equivalent technique, combined with the PDAC EUS-FNB sample, should become a standard for diagnosis to avoid delaying treatment by doing another biopsy. Furthermore, knowledge of the KRAS status from treatment initiation could be used to isolate mutations requiring targeted treatments or inclusion in clinical research trials, especially for wild-type KRAS PDAC.

Diagnostic and theranostic interest of searching for a KRAS mutation in echoendoscopic ultrasound biopsies of pancreatic adenocarcinomas The echoendoscopic ultrasound diagnostic of pancreatic adenocarcinomas sometimes remains difficult due to the nature of these tumors with a particular microenvironment. For more than 30 years, several authors have underlined the importance of searching for a KRAS mutation on samples taken by echoendoscopic ultrasound to improve diagnostic performance. However, this research is not common practice. Our retrospective study made it possible to review the files of 85 patients with pancreatic adenocarcinoma in whom an echoendoscopic ultrasound biopsy was performed with a search for the KRAS mutation (with second-generation fine needle biopsy). Forty-four percent could have been considered positive for the diagnosis of PDAC thanks to the search for the KRAS mutation without repeating new samples. Furthermore, knowledge of the KRAS mutation type from diagnosis would make it possible to isolate mutations justifying possible targeted treatments.

Standardized Pathology Screening of Mature Tertiary Lymphoid Structures in Cancers.

Mature tertiary lymphoid structures (mTLSs) are organized lymphoid structures containing B lymphocytes admixed to CD23+ follicular dendritic cells. Their presence has been linked to improved survival and sensitivity to immune checkpoint inhibitors in several cancers, emerging as a promising pancancer biomarker. However, the requirements for any biomarker are clear methodology, proven feasibility, and reliability. In 357 patients' samples, we studied tertiary lymphoid structures (TLSs) parameters using multiplex immunofluorescence (mIF), hematoxylin-eosin-saffron (HES) staining, double CD20/CD23 staining, and single CD23 immunohistochemistry. The cohort included carcinomas (n = 211) and sarcomas (n = 146), gathering biopsies (n = 170), and surgical specimens (n = 187). mTLSs were defined as TLSs containing either a visible germinal center on HES staining or CD23+ follicular dendritic cells. Focusing on 40 TLSs assessed using mIF, double CD20/CD23 staining was less sensitive than mIF to assess maturity in 27.5% (n = 11/40) but was rescued by single CD23 staining in 90.9% (n = 10/11). In 97 patients, several samples (n = 240) were reviewed to characterize TLS distribution. The likelihood of finding TLSs in surgical material was 6.1 higher than in biopsy and 2.0 higher in primary samples than in metastasis after adjustment with a type of sample. Interrater agreement rates over 4 examiners were 0.65 (Fleiss kappa, 95% CI [0.46, 0.90]) for the presence of TLS and 0.90 for maturity (95% CI [0.83, 0.99]). In this study, we propose a standardized method to screen mTLSs in cancer samples using HES staining and immunohistochemistry that can be applied to all specimens.

Cystic Granulosa Cell Tumors of the Ovary: An Analysis of 80 Cases of an Often Diagnostically Challenging Entity.

CONTEXT.­: Granulosa cell tumors (GCTs) of both adult (AGCT) and juvenile (JGCT) types can rarely be completely or dominantly cystic, creating diagnostic difficulty because the cyst lining epithelium is often denuded. OBJECTIVE.­: To describe clinical, gross, microscopic, immunohistochemical, and molecular features of cystic GCTs with an emphasis on their differential diagnosis. DESIGN.­: We report 80 cystic GCTs (24 AGCTs and 56 JGCTs) in patients from ages 3 to 83 years (average ages, 35 years for AGCT and 22 years for JGCT). RESULTS.­: Nineteen of 43 patients with known clinical information (3 AGCT and 16 JGCT) had androgenic manifestations. All tumors were greater than 8 cm (average, 17 cm) with minimal to absent gross solid component. Denudation of cells lining the cysts was prominent. Invagination of the epithelium into the cyst walls was a key diagnostic feature, was present as cords, trabeculae, solid nests, and small and large follicles, and was identified in most tumors (17 AGCTs and 45 JGCTs). Cytologic atypia was essentially absent in AGCTs, whereas 14 JGCTs showed moderate to severe atypia of bizarre type. A theca cell component was present in all tumors and was extensive in 54. A FOXL2 hotspot mutation was identified in 1 of 4 AGCTs tested. CONCLUSIONS.­: Despite extensive denudation, the finding of typical architectural patterns and cytologic features as well as, in some cases, androgenic manifestations helps differentiate cystic GCTs from follicle cysts, the most common and challenging differential diagnosis, as well as other cystic neoplasms that may enter the differential diagnosis. FOXL2 sequencing may show a false-negative result in cystic AGCT because of the limited number of cells present within the tumor sample.

Comparison of the Idylla™ MSI assay with the Promega™ MSI Analysis System and immunohistochemistry on formalin-fixed paraffin-embedded tissue of endometrial carcinoma: results from an international, multicenter study.

Determination of microsatellite instability (MSI) and mismatch repair deficiency (MMRD), respectively, in endometrial carcinomas (ECs) is important for diagnostic and prognostic purposes, identification of Lynch syndrome carriers, and selection of patients for immunotherapy. The Idylla™ MSI assay is fully automated, does not require non-tumoral tissue, and can be performed in about 150 min. Two hundred forty-two formalin-fixed paraffin-embedded (FFPE) EC samples from 7 international centers were tested by the Idylla™ MSI assay and compared to the Promega™ MSI Analysis System and immunohistochemistry (IHC) for MMR proteins. The cases were selected with an enrichment of MSI EC to around 40%. Concordance was 87.5% between the Idylla™ MSI assay and IHC and 88.58% between IHC and Promega™ MSI assay. Concordance between Idylla™ and Promega™ MSI assays was 89.91%. Discordant results occurred more frequently in cases with MSH6 or PMS2 deficiency. Invalid cases occurred with the three techniques (IHC, 7.00%; Promega™ MSI assay, 5.37%; and Idylla™ MSI assay, 2.47%). The concordance rate between Idylla™ MSI assay and the other 2 methods increased to 88.83% for IHC and to 91.22% for the Promega™ MSI assay when the cutoff of instability in the scoring system was moved from 0.5 to 0.3. The Idylla™ MSI assay is a rapid and highly concordant test for MSI in EC. Modification of the Idylla™ scoring system could increase the sensitivity and specificity of the MSI assay for EC analysis.

Breast hamartoma: reassessment of an under-recognised breast lesion.

AIMS: Breast hamartomas are an under-recognised lesion because they lack a distinctive microscopic appearance. Microscopic diagnosis can often conclude 'no significant lesion' or 'normal breast tissue', leading to repeated biopsies and diagnostic delay. We describe the histological, immunohistochemical and radiological features of breast hamartomas with the aim of identifying specific signs to facilitate their diagnosis and to differentiate them from normal breast and fibroepithelial lesions. METHODS AND RESULTS: Forty-seven breast hamartomas were reassessed (histological diagnosis and imaging features). An immunohistochemical study [oestrogen receptor (ER), progesterone receptor (PR), CD34, high-mobility group A2 (HMGA2)] was performed. On breast imaging, hamartomas most often presented as probably benign solid masses with circumscribed margins and variable densities. Histologically, breast hamartomas resembled normal breast, although their stromal component was predominant, separating randomly scattered epithelial elements with areas of pure collagenous stroma. Pseudoangiomatous stromal hyperplasia (PASH) was present in 93.6% of cases and CD34 antibody highlighted intralobular, perilobular and interlobular distribution of CD34-positive fibroblasts. By comparison, CD34 was mainly expressed in the intralobular normal breast tissue stroma. Hamartoma stromal cells expressed HMGA2, ER and PR in 79%, 66% and 76.3% of our cases, respectively, compared to 7.7%, 23% and 19% in normal breast tissue, respectively (P < 0.0001; P = 0.0005; P < 0.0001). CONCLUSIONS: After ascertaining that core needle biopsy is effectively intralesional, breast hamartomas can be diagnosed with confidence by taking into account the presence of stromal changes, PASH, interlobular distribution of CD34-positive fibroblasts, HMGA2 and hormonal receptor stromal expression.

A subset of epithelioid and spindle cell rhabdomyosarcomas is associated with TFCP2 fusions and common ALK upregulation.

Rhabdomyosarcomas with TFCP2 fusions represent an emerging subtype of tumors, initially discovered by RNA-sequencing. We report herein the clinicopathological, transcriptional, and genomic features of a series of 14 cases. Cases were retrospectively and prospectively recruited and studied by immunohistochemistry (MYF4, MYOD1, S100, AE1/E3, ALK), fluorescence in situ hybridization with TFCP2 break-apart probe (n = 10/14), array-comparative genomic hybridization (Agilent), whole RNA-sequencing (Truseq Exome, Illumina), or anchored multiplex PCR-based targeted next-generation sequencing (Archer® FusionPlex® Sarcoma kit). Patient's age ranged between 11 and 86 years, including 5 pediatric cases. Tumors were located in the bone (n = 12/14) and soft tissue (n = 2/14). Most bone tumors invaded surrounding soft tissue. Craniofacial bones were over-represented (n = 8/12). Median survival was 8 months and five patients are currently alive with a median follow-up of 20 months. Most tumors displayed a mixed spindle cell and epithelioid pattern with frequent vesicular nuclei. All tumors expressed keratins and showed a rhabdomyogenic phenotype (defined as expression of MYF4 and/or MYOD1). ALK was overexpressed in all but three cases without underlying ALK fusion on break-apart FISH (n = 5) nor next-generation sequencing (n = 14). ALK upregulation was frequently associated with an internal deletion at genomic level. TFCP2 was fused in 5' either to EWSR1 (n = 6) or FUS (n = 8). EWSR1 was involved in both soft tissue cases. FISH with TFCP2 break-apart probe was positive in all tested cases (n = 8), including one case with unbalanced signal. On array-CGH, all tested tumors displayed complex genetic profiles with genomic indexes ranging from 13 to 107.55 and recurrent CDKN2A deletions. FET-TFCP2 rhabdomyosarcomas clustered together and distinctly from other rhabdomyosarcomas subgroups. Altogether, our data confirm and expand the spectrum of the new family of FET-TFCP2 rhabdomyosarcomas, which are associated with a predilection for the craniofacial bones, an aggressive course, and recurrent pathological features. Their association with ALK overexpression might represent a therapeutic vulnerability.

Adult Granulosa Cell Tumor With High-grade Transformation: Report of a Series With FOXL2 Mutation Analysis.

Adult granulosa cell tumor (AGCT) is a low-grade malignant neoplasm with a significant propensity for late recurrence and metastasis. Almost all AGCTs are composed of cells with bland nuclear features and even when these tumors recur or metastasize, the nuclear features are almost always low-grade. We report 5 cases of AGCT in patients aged 37 to 88 years composed of areas of typical AGCT with low-grade morphology admixed with areas of high-grade morphology, with marked nuclear atypia, often with bizarre multinucleate cells and high mitotic activity; this is the first reported series of high-grade transformation in AGCTs. The high-grade areas often morphologically closely resembled juvenile granulosa cell tumor with abundant eosinophilic cytoplasm, significant mitotic activity, and intermediate sized follicles. Four cases were FIGO stage IA at diagnosis and 1 was stage IIIC with omental involvement. FOXL2 mutation analysis of both the morphologically low-grade and high-grade areas in 4 of 5 cases confirmed the presence of missense point mutation, c.402C>G, p.(Cys134Trp), providing conclusive evidence that the high-grade component represents transformation of typical AGCT rather than the coexistence of another sex cord-stromal tumor, such as juvenile granulosa cell tumor, which has been suggested for such neoplasms. In 3 of 4 cases where immunohistochemistry was undertaken, there was a striking difference between the p53 staining in the low-grade and high-grade components with wild-type staining in the former and diffuse mutation-type immunoreactivity in the latter, suggesting that TP53 mutation is likely to play a role in high-grade transformation. TP53 mutation analysis covering exons 4 to 10 was undertaken in 4 cases and TP53 mutations were identified in the high-grade component of 2 of the cases. In 1 case, there was diffuse block-type p16 staining in the high-grade component. Follow-up in the 4 stage IA neoplasms revealed no evidence of tumor recurrence in 3 (6 to 9 mo follow-up) while the other patient developed mediastinal, peritoneal, and pulmonary metastasis 17 months after diagnosis. High-grade transformation is uncommon in AGCTs and given that one of our cases was advanced stage at diagnosis, another exhibited widespread metastasis within a short period and there have been occasional case reports of aggressive behavior in AGCTs with high-grade transformation, this event may herald an aggressive clinical course.

Hepatotoxicities Induced by Neoadjuvant Chemotherapy in Colorectal Cancer Liver Metastases: Distinguishing the True From the False.

BACKGROUND: Pre-operative chemotherapy for colorectal liver metastasis (CRLM) is thought to be the cause of hepatotoxicity of non-tumoural parenchyma. Studies on hepatotoxicity are contradictory. We investigated the impact of a single-line pre-operative chemotherapy on non-tumoural liver analysed by an expert hepatico-pancreatico-biliary pathologist, and the consequences on surgical outcomes. PATIENTS AND METHODS: Patients operated for CRLM, after a pure first-line pre-operative chemotherapy, were retrospectively included. Two comparative histopathological analyses were performed for vascular toxicity and steatohepatitis. RESULTS: Between 2003 and 2015, 147 patients were included. Chemotherapy was based on oxaliplatin (40.1%), irinotecan (55.8%), or both (4.1%). The expert pathologist described 38.8% of vascular lesions including dilation, nodular regeneration, and peliosis. In multivariate analysis, vascular lesions correlated to male sex (P = .01), pre-operative platelets <150 g/L (P = .04), and aspartate aminotransferase to platelet ratio index (APRI) score >0.36 (P = .02). Steatohepatitis was observed in 15 patients (10.2%), more frequently after irinotecan (14.8% vs 3.4%, P = .01; odds ratio [OR] = 7.3; 95% confidence interval [CI] = [1.5-34.7]), and for patients with body mass index (BMI) >25 kg/m2 (P = .004; OR = 10.0; 95% CI = [2.1-47.5]). A total of 29 patients (19.7%) developed major complications with 2 risk factors: portal vein obstruction (PVO) and septic surgery. Reproducibility assessment of steatohepatitis and dilated lesions by 2 pathologists showed moderate agreement (Kappa score 0.53 and 0.54, respectively). CONCLUSIONS: There is a probable association between non-alcoholic steatohepatitis (NASH) and irinotecan. Oxaliplatin seems to lead to higher vascular lesions. Except in the presence of pre-existent comorbidities, liver toxicities should not restrain the use of pre-operative chemotherapy prior to parenchymal-sparing surgery.

SOX10, GATA3, GCDFP15, Androgen Receptor, and Mammaglobin for the Differential Diagnosis Between Triple-negative Breast Cancer and TTF1-negative Lung Adenocarcinoma.

Triple-negative breast cancer (TNBC) patients have an increased risk of developing visceral metastases and other primary nonbreast cancers, particularly lung cancer. The differential diagnosis of TNBC metastases and primary cancers from other organs can be difficult due to lack of a TNBC standard immunoprofile. We analyzed the diagnostic value of estrogen receptor, progesterone receptor, human epidermal growth factor receptor, thyroid transcription factor-1 (TTF1), Napsin A, mammaglobin, gross cystic disease fluid protein 15 (GCDFP15), Sry-related HMg-Box gene 10 (SOX10), GATA-binding protein 3 (GATA3), and androgen receptor in a series of 207 TNBC and 152 primary lung adenocarcinomas (LA). All tested TNBCs were TTF1 and Napsin A-negative. When comparing TNBC and TTF1-positive or negative LA, SOX10 had the best sensitivity (62.3%) and specificity (100%) as a marker in favor of TNBC compared with LA, irrespective of TTF1 status (P<0.0001). GATA3 had moderate sensitivity (30.4%) and excellent specificity (98.7%) and misclassified only 2/152 LA (1.3%). GCDFP15 had a moderate sensitivity (20.8%) and excellent specificity (98%) and misclassified only 3/152 (2%) LA. Mammaglobin and androgen receptor had moderate sensitivities (38.2% and 30%), good specificities (81.6% and 86%), and misclassified 28/152 and 21/152 LAs, respectively. In multivariate analysis, the best markers, enabling the distinction between SOX10-negative TNBC and TTF1 and Napsin A-negative LA were GATA3 (odds ratio=33.5; 95% confidence interval, 7.3-153.5; P<0.0001) and GCDFP15 (odds ratio=31.7; 95% confidence interval, 6.9-145.6; P<0.0001). Only 13/207 (6.3%) TNBC cases did not express any aforementioned marker. On the basis of our results, the best sequential immunohistochemical analysis to differentiate TNBC from TTF1-negative LA is first SOX10 followed by GATA3, and finally GCDFP15. This order is important in the diagnostic workup of small biopsies from lung nodules in women with a previous history of TNBC.

GREB1-CTNNB1 fusion transcript detected by RNA-sequencing in a uterine tumor resembling ovarian sex cord tumor (UTROSCT): A novel CTNNB1 rearrangement.

Mutations of CTNNB1 have been implicated in tumorigenesis in many organs. However, tumors harboring a CTNNB1 translocation are extremely rare and this translocation has never been reported in a uterine mesenchymal neoplasm. We report a novel translocation t(2;3)(p25;p22) involving the GREB1 (intron 8) and CTNNB1 (exon 3) in a uterine tumor resembling ovarian sex cord tumor (UTROSCT), which exhibited extrauterine metastasis. The translocation detected by RNA-sequencing was validated by RT-PCR, and resulted in nuclear expression of ß-catenin. Juxtapositioning with GREB1, which is overexpressed in response to estrogens, resulted in overexpression of a truncated and hypophosphorylated nuclear ß-catenin in the primary and recurrent tumors. This accumulation of nuclear ß-catenin results in a constitutive activation of the Wnt/ß-catenin signaling pathway with a major oncogenic effect. The CTNNB1 gene fusion, promoted by an estrogen-responsive gene (GREB1), could be a potential driver of tumorigenesis in this case and a therapeutic target with adapted inhibitors. RT-PCR and immunohistochemistry performed on 11 additional UTROSCTs showed no CTNNB1 fusion transcript or nuclear ß-catenin immunoreactivity.

Parenchymal sparing surgery brings treatment of colorectal liver metastases into the precision medicine era.

The treatment of advanced colorectal liver metastases (CRLMs) follows the biphasic pattern characteristic of oncological surgery. A phase of escalation-the therapeutic aggressiveness-is followed by a phase of de-escalation aimed at decreasing the morbidity, while preserving the gains in survival. From a maximum of three lesions, the rule no longer limits the number, provided the intervention does not cause lethal liver failure. Technically feasible non-anatomical resections, two-stage hepatectomies, portal vein obliteration and so forth, have pushed the boundaries of surgery far. However, the impact and the biology of metastatic processes have been long ignored. Parenchymal sparing surgery (PSS) is a de-escalation strategy that targets only metastasis by minimising the risk of stimulating tumour growth, while enabling iterative interventions. Reducing the loss of healthy parenchyma increases the tolerance of the liver to interval chemotherapy. Technically, PSS could use any type of hepatectomy, providing it is centred on the metastatic load alongside intraoperative ablation. The PSS concept sometimes wrongly comes across as a debate between minor versus major hepatectomies. Hence, we propose a clear definition, both quantitative and qualitative, of what PSS is and what it is not. Conversely, the degree of selectivity of PSS as a percentage of the volume of resected metastases versus the volume of total liver removed has not been stopped to date and should be the subject of prospective studies. Ultimately, the treatment of advanced CRLMs, of which PSS is a part, needs to be personalised by the multidisciplinary team by adapting its response to each new recurrence.

Parenchymal sparing surgery for colorectal liver metastases: The need for a common definition.

BACKGROUND: The definition of parenchymal sparing surgery (PSS) for colorectal liver metastases (CRLM) diverges requiring a clarification of the concept. METHOD: A consecutive series of patients were treated by PSS for their CRLMs, either by resection or intra-operative ablation (IOA), whenever possible a one-stage surgery and minimal usage of portal vein embolization. Post-operative complications were the primary endpoint with a special focus on post-operative liver failure. RESULTS: Three hundred and eighty-seven patients underwent a PSS out of which 328 patients received a median of 9 pre-operative cycles of chemotherapy. One hundred and twenty-eight patients had a major resection, combined with IOA in 137 patients and IOA alone in 50 cases. The 5yr-overall survival was 50.3%. There was no difference in post-operative complications between minor and major resections, validating our PSS definition based on the Tumor burden/Healthy liver ratio and not just the retrieved volume. CONCLUSIONS: PSS is defined as a high ratio of tumoral burden per specimen retrieved while favoring one-stage surgery approach. Our series, using combined resections and IOAs, matches this definition well. Furthermore, complications were correlated neither to chemotherapy nor to liver-induced toxicities, contrary to extended hepatectomies.

Molecular Pathology of Anaplastic Thyroid Carcinomas: A Retrospective Study of 144 Cases.

BACKGROUND: Anaplastic thyroid carcinoma (ATC) is a rare tumor, with poorly defined oncogenic molecular mechanisms and limited therapeutic options contributing to its poor prognosis. The aims of this retrospective study were to determine the frequency of anaplastic lymphoma kinase (ALK) translocations and to identify the mutational profile of ATC including TERT promoter mutations. METHODS AND MATERIALS: One hundred and forty-four ATC cases were collected from 10 centers that are a part of the national French network for management of refractory thyroid tumors. Fluorescence in situ hybridization analysis for ALK rearrangement was performed on tissue microarrays. A panel of 50 genes using next-generation sequencing and TERT promoter mutations using Sanger sequencing were also screened. RESULTS: Fluorescence in situ hybridization was interpretable for 90 (62.5%) cases. One (1.1%) case was positive for an ALK rearrangement with a borderline threshold (15% positive cells). Next-generation sequencing results were interpretable for 94 (65.3%) cases, and Sanger sequencing (TERT) for 98 (68.1%) cases. A total of 210 mutations (intronic and exonic) were identified. TP53 alterations were the most frequent (54.4%). Forty-three percent harbored a mutation in the (H-K-N)RAS genes, 13.8% a mutation in the BRAF gene (essentially p.V600E), 17% a PI3K-AKT pathway mutation, 6.4% both RAS and PI3K pathway mutations, and 4.3% both TP53 and PTEN mutations. Nearly 10% of the cases showed no mutations of the RAS, PI3K-AKT pathways, or TP53, with mutations of ALK, ATM, APC, CDKN2A, ERBB2, RET, or SMAD4, including mutations not yet described in thyroid tumors. Genes encoding potentially druggable targets included: mutations in the ATM gene in four (4.3%) cases, in ERBB2 in one (1.1%) case, in MET in one (1.1%) case, and in ALK in one (1.1%) case. A TERT promoter alteration was found in 53 (54.0%) cases, including 43 C228T and 10 C250T mutations. Three out of our cases did not harbor mutations in the panel of genes with therapeutic interest. CONCLUSION: This study confirms that ALK rearrangements in ATC are rare and that the mutational landscape of ATC is heterogeneous, with many genes implicated in the follicular epithelial cell dedifferentiation process. This may explain the limited effectiveness of targeted therapeutic options tested so far.

[Sciatic nerve intraneural perineurioma]. / Périneuriome intraneural du nerf sciatique.

Intraneural perineurioma is a benign tumor developed from the perineurium and responsible for localized nerve hypertrophy. This uncommon tumor is characterized by a proliferation of perineural cells with a "pseudo-onion bulb" pattern. We report a sciatic nerve intraneural perineurioma in a 39-year-old patient.

Identification of a recurrent STRN/ALK fusion in thyroid carcinomas.

Thyroid carcinoma is the most common endocrine malignant tumor and accounts for 1% of all new malignant diseases. Among all types and subtypes of thyroid cancers that have been described so far, papillary thyroid carcinoma is the most frequent. The standard management treatment of these tumors consists of surgery, followed by radioiodine treatment in case of high risk of relapse. The most aggressive forms are commonly treated by chemotherapy, radiotherapy or experimental drug testing. We recently reported the case of a patient presenting an anaplastic thyroid carcinoma with lung metastases. Fluorescence in situ hybridization analysis allowed us to detect a rearrangement of the anaplastic lymphoma kinase (ALK) gene in both tumors. The patient was treated with crizotinib and presented an excellent drug response. We present here the subsequent investigations carried out to further characterize this genetic alteration and to assess the prevalence of ALK rearrangements in thyroid lesions. High resolution array-comparative genomic hybridization data complemented by RT-PCR and sequencing analyses, allowed us to demonstrate the presence of a STRN/ALK fusion. The STRN/ALK transcript consisted of the fusion between exon 3 of STRN and exon 20 of ALK. Subsequent screening of 75 various thyroid tumors by RT-PCR revealed that 2 out of 29 papillary thyroid carcinomas exhibited the same fusion transcript. None was detected in other types of malignant or benign thyroid lesions analyzed. These findings could pave the way for the development of new targeted therapeutic strategies in the treatment of papillary thyroid carcinomas and point to ALK inhibitors as promising agents that merit rapid evaluation.