BACKGROUND: Molecular testing has been used as an adjunct to morphological evaluation in the workup of thyroid nodules. This study investigated the impact of two gene fusions, RET/PTC and THADA/IGF2BP3, that have been described as oncogenic events in thyroid neoplasms.
METHODS: We performed a retrospective, single-centered study at a McGill University teaching hospital in Montreal, Canada, from January 2016 to August 2021. We included patients who underwent surgery for thyroid nodules that pre-operatively underwent molecular testing showing either RET/PTC or THADA/IGF2BP3 gene fusion.
RESULTS: This study included 697 consecutive operated thyroid nodules assessed using molecular testing, of which five had the RET/PTC fusion and seven had the THADA/IGF2BP3 fusion. Of the five nodules in the RET/PTC group, 100% were malignant and presented as Bethesda V/VI. Eighty percent (4/5) were found to have lymph node metastasis. Twenty percent (1/5) had extrathyroidal extensions. Sixty percent (3/5) were a diffuse sclerosing variant of papillary thyroid carcinoma, and the rest were the classical variant. Of the seven THADA/IGF2BP3 nodules, all presented as Bethesda III/IV and 71.4% (5/7) were malignant based on the final pathology analysis, and 28.6% (2/7) were NIFTP. All the THADA/IGF2BP3 fusion malignancies were a follicular variant of papillary thyroid carcinoma. None had lymph node metastasis or displayed extrathyroidal extensions.
CONCLUSIONS: RET/PTC nodules presented as Bethesda V/VI and potentially had more aggressive features, whereas THADA/IGF2BP3 nodules presented as Bethesda III/IV and had more indolent behavior. This understanding may allow clinicians to develop more targeted treatment plans, such as the extent of surgery and adjuvant radioactive iodine treatment.

Increasing concern regarding non-treatment and relapse in Acute Lymphoblastic Leukemia (ALL) among children and adults has attracted the attention of researchers to investigate the genetic factors of ALL and discover new treatments with a better prognosis. Nevertheless, the survival rate in children is more than in adults; therefore, it is necessary to find new potential molecular targets with better therapeutic results. Genomic analysis has enabled the detection of different genetic defects that are serious for driving leukemogenesis. The study of genetic translocation provides a better understanding of the function of genes involved in disease progression. This paper presents an overview of the main genetic translocations and dysregulations in the signaling pathways of ALL. We also report the inhibitors of these main translocations and evaluate the synergistic effect of chemical inhibitors and gamma-ray irradiation on ALL.

Objective: 45, X is a very rare condition that usually results from Y/autosomal translocations or insertions. Here we present an infertile azoospermic man who had 45, X t(Yp;15) karyotype and deletion of AZF (azoospermia factor) gene region. Case report : A 35-year-old infertile azoospermic man with a typical male appearance came for infertility genetic counseling. He was infertile for more than ten years and had short height. High-resolution of metaphase chromosomes of 50 peripheral white blood cells were analyzed for karyotyping. Fluorescence in situ hybridization (FISH) analysis and Polymerase chain reaction (PCR) were done for SRY and AZF gene localization. Karyotyping and FISH analysis revealed 45, X t(Yp;15) karyotype and no mosaicism. More investigation on the Y chromosome revealed no deletion in the SRY region, but AZF a/b/c were deleted. It was revealed that Yp\'s subtelomeric region but not Yq was translocated to chromosome 15. Conclusion: This study shows that despite the lack of a complete Y chromosome in this person, the occurrence of secondary male traits is a result of the short arm translocation of the Y chromosome, which contains the (ex-determining region Y) SRY gene. Infertility is also due to the Y chromosomes long arm\'s deletion containing the AZF gene region.

Neurotrophic tropomyosin receptor kinase (NTRK) gene fusions are emerging tissue-agnostic drug targets in malignancies including colorectal carcinomas (CRCs), but their detailed landscape in the context of various colorectal carcinogenesis pathways remains to be investigated. In this study, pan-tropomyosin receptor kinase (TRK) protein expression was assessed by immunohistochemistry (IHC) in retrospectively collected colorectal epithelial tumor tissues, including 441 CRCs [133 microsatellite instability-high (MSI-high) and 308 microsatellite stable (MSS)] and 595 premalignant colorectal lesions (330 serrated lesions and 265 conventional adenomas). TRK-positive cases were then subjected to next-generation sequencing and/or fluorescence in situ hybridization to confirm NTRK rearrangements. TRK IHC positivity was not observed in any of the MSS CRCs, conventional adenomas, traditional serrated adenomas, or hyperplastic polyps, whereas TRK positivity was observed in 11 of 58 (19%) MLH1-methylated MSI-high CRCs, 4 of 23 (17%) sessile serrated lesions with dysplasia (SSLDs), and 5 of 132 (4%) sessile serrated lesions (SSLs). The 11 TRK-positive MSI-high CRCs commonly harbored CpG island methylator phenotype-high (CIMP-high), MLH1 methylation, BRAF/KRAS wild-type, and NTRK1 or NTRK3 fusion (TPM3-NTRK1, TPR-NTRK1, LMNA-NTRK1, SFPQ-NTRK1, ETV6-NTRK3, or EML4-NTRK3). Both NTRK1 or NTRK3 rearrangement and BRAF/KRAS wild-type were detected in all nine TRK-positive SSL(D)s, seven of which demonstrated MSS and/or CIMP-low. TRK expression was selectively observed in distorted serrated crypts within SSLs and was occasionally localized at the base of serrated crypts. NTRK fusions were detected only in SSLs of patients aged ≥50 years, whereas BRAF mutation was found in younger age-onset SSLs. In conclusion, NTRK-rearranged colorectal tumors develop exclusively through the serrated neoplasia pathway and can be initiated from non-dysplastic SSLs without BRAF/KRAS mutations prior to full occurrence of MSI-high/CIMP-high. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Perivascular epithelioid cell neoplasms (PEComas) are a family of mesenchymal neoplasms with features of both melanotic and smooth muscle differentiation. PEComa morphology is highly variable and encompasses epithelioid to spindle cells often with clear cytoplasm and prominent nucleoli. Molecularly, most PEComas are defined by a loss of function of the TSC1/TSC2 complex. Additionally, a distinct small subset of PEComas harboring rearrangements of the TFE3 (Xp11) gene locus has been identified. By presenting a series of three case reports with distinct features, we demonstrate diagnostic pitfalls as well as the importance of molecular work-up of PEComas because of important therapeutic consequences.

The exponential rate at which genetic testing has been integrated into routine and high-risk obstetric care has been exciting to watch. With this technical explosion, however, the knowledge surrounding the benefits and limitations of prenatal genetic and newborn screening can be overlooked by both parents and providers. The following case exemplifies how a couple with infertility who underwent comprehensive prenatal expanded genetic carrier screening and parental karyotype experienced the benefits and limitations of such testing. It guides the reader through diagnostic testing for an infant, born to a father with a balanced translocation, who presented with an abnormal newborn screening result for an inherited metabolic disorder of fatty acid oxidation metabolism, very-long-chain acyl-coenzyme dehydrogenase deficiency, for which the prenatal expanded carrier screening result was negative.

Round-cell sarcomas represent highly malignant tumors that occur predominantly in children, adolescents, and young adults. Round-cell sarcomas are caused by recurrent translocations that involve certain transcription factors. Ewing\'s sarcoma, Ewing-like sarcomas (e.g. CIC-DUX positive or BCOR positive sarcomas), desmoplastic small round-cell tumors (DSRCTs), and alveolar rhabdomyosarcomas (ARMs) are typical examples of this particular group of sarcomas. These entities differ in their tumor genetics, which is correlated with immunohistochemical expression profiles and with clinical phenotypes. Classification should be based on molecular findings. Immunohistochemistry may serve as a surrogate marker.

Perivascular epithelioid cell neoplasms (PEComas) are a family of mesenchymal neoplasms with features of both melanotic and smooth muscle differentiation. PEComa morphology is highly variable and encompasses epithelioid to spindle cells often with clear cytoplasm and prominent nucleoli. Molecularly, most PEComas are defined by a loss of function of the TSC1/TSC2 complex. Additionally, a distinct small subset of PEComas harboring rearrangements of the TFE3 (Xp11) gene locus has been identified. By presenting a series of three case reports with distinct features, we demonstrate diagnostic pitfalls as well as the importance of molecular work-up of PEComas because of important therapeutic consequences.

Spindle cell tumors in childhood are rare lesions with a heterogeneous morphological picture and clinical course, ranging from benign lesions to fully malignant tumors. The clinical assessment of these tumors is often challenging since some of them show fast growth dynamics but are utterly benign, while a subset of slow-growing tumors can represent malignant entities. Due to the rarity of these tumors as well as the overlapping morphology and the often uncharacteristic immunohistochemical profiles, the pathologic diagnosis is often also difficult. This review gives an overview of some of the more common pediatric spindle cell tumors. In addition to the morphological features and immunohistochemical aspects, specific molecular changes are discussed. Here, some of the newly described translocations that may imply therapeutic options, are presented.

The update of the 4th edition of the WHO classification for hematopoietic neoplasms introduces changes in the field of mature aggressive B‑cell lymphomas that are relevant to diagnostic pathologists. In daily practice, the question arises of which analysis should be performed when diagnosing the most common lymphoma entity, diffuse large B‑cell lymphoma. We discuss the importance of the cell of origin, the analysis of MYC translocations, and the delineation of the new WHO entities of high-grade B‑cell lymphomas.