Histopathological Features of Pendred Syndrome Thyroids Align with Differences in the Expression of Thyroid-Specific Markers, Apical Iodide Transporters, and Ciliogenesis Process.

Pendred syndrome (PDS) is an autosomal recessive disorder caused by mutations in the gene that encodes pendrin. Pendred thyroid tissue is supposedly altered by the absence of functional pendrin, but it is still unknown whether other iodide exchangers could compensate for the loss of the protein. Moreover, we have recently described that primary cilium, a conserved structure present at the apical surface of normal follicular cells, suffers different alterations in functional thyroid diseases. We aimed (1) to better understand the histopathological changes experienced by PDS thyroids, (2) to analyze the expression of different thyroid-specific genes and alternative iodide transporters and, finally, (3) to determine whether those changes may alter the morphological pattern of primary cilia in follicular cells. Thyroid samples from a series of four PDS patients were analyzed by immunohistochemistry, double immunofluorescence, and morphometry to evaluate changes in primary cilia frequency and length. We found thyroid follicular nodular disease in all PDS thyroids, frequently in association with follicular adenomas. There were only slight changes in the expression of thyroid-specific markers. Although no positivity for pendrin was found, cytoplasmic immunostaining for ANO-1, CLC-5, and CFTR was stronger in diffuse hyperplastic areas when compared to areas with highly cellular follicular nodules (HCFNs). HCFNs and follicular adenomas always showed diminished ciliary frequency and length. Our results suggest a direct relationship between the absence of functional pendrin and the loss of the normal thyroid architecture in PDS patients, which was also accompanied by differences in the expression of specific immunohistochemical markers and altered ciliogenesis. The present data may help the pathologist in screening for PDS.

Exome sequencing of early-onset patients supports genetic heterogeneity in colorectal cancer.

Colorectal cancer (CRC) is a complex disease that can be caused by a spectrum of genetic variants ranging from low to high penetrance changes, that interact with the environment to determine which individuals will develop the disease. In this study, we sequenced 20 early-onset CRC patients to discover novel genetic variants that could be linked to the prompt disease development. Eight genes, CHAD, CHD1L, ERCC6, IGTB7, PTPN13, SPATA20, TDG and TGS1, were selected and re-sequenced in a further 304 early onset CRC patients to search for rare, high-impact variants. Although we found a recurring truncating variant in the TDG gene shared by two independent patients, the results obtained did not help consolidate any of the candidates as promising CRC predisposing genes. However, we found that potential risk alleles in our extended list of candidate variants have a tendency to appear at higher numbers in younger cases. This supports the idea that CRC onset may be oligogenic in nature and may show molecular heterogeneity. Further, larger and robust studies are thus needed to unravel the genetics behind early-onset CRC development, coupled with novel functional analyses and omic approaches that may offer complementary insight.

Early evolutionary divergence between papillary and anaplastic thyroid cancers.

Background: Papillary thyroid cancer (PTC) is the most common thyroid carcinoma and exhibits an almost uniformly good prognosis, while anaplastic thyroid cancer (ATC) is less frequent and is one of the most aggressive cancers usually resistant to conventional treatment. Current hypothesis posits that ATC derives from PTC through the progressive acquisition of a discrete number of genomic alterations and implies that the mutational landscape of ATC resembles that of PTC. However, the clinical behaviour of ATC and PTC is radically different. We decided to address the disconnection between the clinical behaviour of ATC and PTC and the proposed model of the progressive development of ATC from PTC. Patients and methods: We carried out exome sequencing of DNA from 14 ATC specimens including three cases of concomitant ATC and PTC as well as their corresponding normal DNA from 14 patients. The sequencing results were validated using droplet digital PCR. We carried out immunohistochemistry and immunofluorescence studies of the concomitant ATC and PTC cases. In addition, we integrated our sequencing results with the existing TCGA data. Results: Most of the somatic mutations identified in the ATC component differed from the ones in PTC in the cases of concomitant ATC and PTC. The trunks of the phylogenetic trees representing the somatic mutations were short with long branches. In one case of concomitant PTC and ATC specimens, we observed an infiltration of PTC cells within the ATC component. Moreover, we integrated our results with data obtained from TCGA and observed that the most frequent mutations found in ATC presented high cancer cell fraction values and were significantly different from the PTC ones. Conclusion: ATC diverge from PTC early in tumour development and both tumour types evolve independently. Our work allows the understanding of the relationship between ATC and PTC facilitating the clinical management of these malignancies.

EWSR1 rearrangement is a frequent event in papillary thyroid carcinoma and in carcinoma of the thyroid with Ewing family tumor elements (CEFTE).

Carcinomas of the thyroid with Ewing family tumor element (CEFTEs) are small-cell thyroid tumors with epithelial differentiation that disclose p63 expression and EWSR1-FLI1 rearrangement, carry a favorable prognosis and may co-exist with papillary thyroid carcinoma (PTC) foci. Two histogenetic hypotheses have been advanced regarding the origin of CEFTEs: arising in PTCs or in solid cell nests (SCN). A total of 3 CEFTEs, 54 PTCs, and 10 SCNs were reviewed, and fluorescence in situ hybridization (FISH) technique was performed in all cases to search for the presence of EWSR1 rearrangements. The three CEFTEs disclosed the EWSR1-FLI1 rearrangement both in the small cell and in the PTC component. Out of the 54 PTC cases, 28 (51.9%) were positive, 20 (37.0%) were negative, and 6 (11.1%) were inconclusive for EWSR1 rearrangement; in two of the positive PTC cases, the EWSR1-FLI1 rearrangement was detected. Classic PTC disclosed more often the EWSR1 rearrangement than other PTC variants (p = 0.031). PTCs with EWSR1 rearrangement disclosed a lower percentage of nuclei with EWSR1 polysomy than those without EWSR1 rearrangement (p = 0.001). Out of the 10 SCNs, 7 (70.0%) were negative and 3 (30.0%) were inconclusive for the EWSR1 rearrangement. Monosomic nuclei were more frequent (mean of 44.3%) in SCNs than in PTCs (p < 0.001). The presence of the EWSR1-FLI1 rearrangement in PTC component of all studied CEFTEs and the existence of the EWSR1 rearrangement in some PTCs favor the origin of CEFTE from PTC. The high frequency of EWSR1 rearrangements in PTC may represent a new diagnostic marker of these tumors.

High incidence of large deletions in the PMS2 gene in Spanish Lynch syndrome families.

Lynch syndrome (LS) is caused by germline mutations in one of the four mismatch repair (MMR) genes. Defects in this pathway lead to microsatellite instability (MSI) in DNA tumors, which constitutes the molecular hallmark of this disease. Selection of patients for genetic testing in LS is usually based on fulfillment of diagnostic clinical criteria (i.e. Amsterdam criteria or the revised Bethesda guidelines). However, following these criteria PMS2 mutations have probably been underestimated as their penetrances appear to be lower than those of the other MMR genes. The use of universal MMR study-based strategies, using MSI testing and immunohistochemical (IHC) staining, is being one proposed alternative. Besides, germline mutation detection in PMS2 is complicated by the presence of highly homologous pseudogenes. Nevertheless, specific amplification of PMS2 by long-range polymerase chain reaction (PCR) and the improvement of the analysis of large deletions/duplications by multiplex ligation-dependent probe amplification (MLPA) overcome this difficulty. By using both approaches, we analyzed 19 PMS2-suspected carriers who have been selected by clinical or universal strategies and found five large deletions and one frameshift mutation in PMS2 in six patients (31%). Owing to the high incidence of large deletions found in our cohort, we recommend MLPA analysis as the first-line method for searching germline mutations in PMS2.

[New report of epididymal adenomatoid tumor. Infrequent pathology]. / Nueva aportación de un tumor adenomatoide de epididimo. Una patología poco frecuente.

Case report of a 42-year old patient with an epididymal adenomatoid tumour found after a three-month history of increased left hemiscrotum and scrotal discomfort. Definite diagnosis was arrived at following surgical exeresis and pathoanatomical study. The etiopatogenesis, clinical presentation and management are all analyzed. Since urological incidence is very low within intrascrotal processes, we believe it is important to understand the condition so that a differential diagnosis from other inflammatory processes can be established; also the convenience of a much more aggressive attitude in scrotal diseases is restated due to the low morbidity of this type of surgery.

[Adenocarcinoma at an ileostomy site after colectomy for ulcerative colitis]. / Adénocarcinome sur iléostomie apparaissant après une colectomie réalisée pour colite ulcéreuse.

In this article we present the tenth case, according to the literature, of adenocarcinoma occurring at a long standing ileostomy originally performed for ulcerative colitis. Study of this and previous cases demonstrates common factors such as a previous history of ulcerative colitis, a long interval until the appearance of symptoms, together with a similar clinical and pathological characterisation with invasion of neighbouring skin layers close to the ileostomy. Several pathogenic hypotheses are considered. We believe that local excision in oder to obtain the diagnosis is a better option than a sampling biopsy and that surgery should include a wide resection of the abdominal wall and intestine in order to comply with therapeutic criteria in malignant disease.