Thyroid cancer is the most common malignancy of the endocrine system. Fine-needle aspiration (FNA) biopsy of thyroid nodules has become the gold standard procedure, in terms of cost and efficacy, for guiding clinicians towards appropriate patients’ management. One challenge for cytopathologists is to accurately classify cytological specimens as benign or malignant based on cytomorphological features. In fact, with a frequency ranging from 10% to 30%, nodules are diagnosed as indeterminate. In recent years, the mutational landscape of thyroid tumors has been extensively described, and two molecular profiles have been identified: RAS-like (NRAS, HRAS, and KRAS mutations; EIF1AX mutations; BRAF K601E mutation; and PPARG and THADA fusions) and BRAF^V600E-like (including BRAF^V600E mutation and RET and BRAF fusions). The purpose of this review is to discuss the latest molecular findings in the context of indeterminate thyroid nodules, highlighting the role of molecular tests in patients’ management.

Patients with metastatic lung adenocarcinoma (mADC) harboring EGFR-activating mutations can benefit from first-line Osimertinib, but acquired resistance inevitably occurs. Different resistance mechanisms, on- and off-target, have been described. Here, we evaluated the prevalence of phenotypic transformation as a resistance mechanism in a consecutive series of EGFR-mutated mADC, diagnosed at our institution, and on the basis of literature data. A consecutive 3-year series of non-small cell lung cancer (NSCLC) was reviewed according to histological and molecular characteristics. A total of 100 mADCs harboring EGFR exon-19 deletions (61 cases) and the p.(L858R) mutation (39 cases) were selected. All cases were treated by first-line Osimertinib. The prevalence and type of phenotypic transformation were evaluated in patients with available rebiopsy at the time of first-line progression. A total of 32 mADC patients underwent rebiopsy upon first-line Osimertinib progression, and 23 cases had EGFR exon-19 in-frame deletions and 9 p.(L858R) mutations. Four cases showed a phenotypic transformation after a median of 15 months from the start of Osimertinib treatment. All these cases harbored EGFR exon-19 deletions and TP53 pathogenic mutations on diagnostic tumor tissues. Three cases switched to small cell lung cancer histology; in one case, a MET amplification was also detected on rebiopsy. One case changed to spindle cell carcinoma. All cases maintained the initial activating EGFR alteration. For three cases, liquid biopsy was performed at the time of progression: one was negative, one presented only an EGFR exon-19 deletion, and one presented only a MET amplification. In our study, phenotypic transformation had a considerable prevalence among EGFR-positive mADC patients treated by first-line Osimertinib. Different types of histological changes were detected as the only resistance mechanism except for one case with a simultaneously acquired MET amplification. Moreover, all cases harbored TP53 alterations, influencing treatment response. Despite the usefulness of liquid biopsy, rebiopsy should be executed whenever possible. Indeed, it remains the only tool for assessing histological transformation, which greatly impacts prognosis and treatment decisions.

Cluster of Differentiation 47 (CD47), an innate immune checkpoint, facilitates immune escape by binding signal regulatory protein alpha (SIRPα) to inhibit macrophage phagocytosis. Its significance in colorectal cancer (CRC) has garnered heightened interest. This review summarizes five immunohistochemistry (IHC) studies and complementary transcriptomic analyses assessing CD47 in CRC. IHC results consistently indicated membrane overexpression, though positivity rates varied widely (16–91%) due to methodological heterogeneity. Transcriptomic results confirmed CD47 upregulation, especially in Consensus Molecular Subtype 1 (CMS1) and CMS4 subtypes and revealed co-expression with immune checkpoints and oncogenic pathways. Clinically, high CD47 levels were associated with advanced TNM stage, metastasis, poor differentiation, and altered immune infiltration; however, the prognostic significance varied among cohorts. Overall, CD47 appears to be a promising biomarker and therapeutic target, but clinical translation requires standardized evaluation, including harmonized antibody selection and scoring cut-offs, and prospective validation.

Papillary thyroid cancer (PTC) is linked to obesity, but the biological mechanisms that may explain this connection have been only partially described. Potential factors that combine overweight/obesity with this cancer should be searched for in the immune pathways and chronic inflammation onset. In this study, we evaluated the role of the immune system in patients affected by PTC and stratified them according to Body Mass Index (BMI). An analysis of the expression profiles of >700 immune-related genes was performed in 36 PTCs, subdivided into four categories: underweight (A), normal weight (B), overweight (C), and subjects living with obesity (D). B was considered a reference category. In our study, the immune microenvironment of PTCs did not seem strongly influenced by BMI. However, based on the interaction from in silico protein–protein analysis, we found that the dysregulation profiles of groups A or D were similar as concerns pathways involved in T-cell differentiation, macrophage activation, regulation of the cell cycle, and senescence processes. Furthermore, we found significant downregulation of HMGB1 in the A and D categories, with upregulation of ARG2 in the D category. Although further studies are necessary, these genes may provide an opportunity to better understand immunometabolism in thyroid cancer.

Background/Objectives: Pleural and peritoneal mesothelioma (PL and PE) are aggressive diseases, accounting for 68.0–92.4% and 6.9–24.1% of all cases. To improve both diagnosis and management of these patients, a deeper knowledge and characterization of the molecular background are necessary. Although molecular profiling of PL has been largely investigated in recent years, much less is known about the genomic landscape of PE, due to its rarity. Here, we aim to compare gene expression profiling of pleural and peritoneal mesothelioma to underline main differences and to identify new potential histotype-specific biomarkers. Methods: We performed a gene expression analysis of 32 epithelioid PL and 21 epithelioid PE cases, diagnosed from 2017 to 2023 at the University Hospital of Pisa, using an nCounter custom panel including 117 target genes known for their crucial role in cancer. Results: PE, compared to PL, showed different expression levels of genes related to extracellular matrix modification (ECM), as collagen alteration, pro-inflammatory and angiogenic response (mediated by NF-κB). In detail, in PE we observed a significant upregulation of metalloproteinase-1 (MMP1), E-selectin (SELE), pappalysin-1 (PAPPA), estrogen receptor-2 (ESR2) and transportin-2 (TNPO2); and a downregulation of pyruvate kinase (PKM). Furthermore, BAP1 loss was associated with distinct gene deregulation in PE and PL; the only exception was ASS1 upregulation, which was observed in both histologies. These insights may help refine the utility of BAP1 as a biomarker. Conclusions: Deregulated genes in PE deserve further investigation as potential biomarkers, according to their biological role. In fact, MMPs and PAPPA impact migration ability and angiogenic response of mesothelioma, while PKM and ESR2 are usually investigated for their involvement in reprogramming of energy metabolism. The identification of histotype-specific biomarkers is warranted to improve mesothelioma management.

The 2022 WHO classification gives more importance to the integration of morphological and molecular characteristics of tumors, introducing new diagnostic criteria for papillary thyroid carcinoma (PTC). The invasive encapsulated follicular variant of PTC (IEFVPTC) is now considered a separate entity and no longer a subtype of PTC, while the infiltrative follicular variant (IFVPTC) is still considered a PTC subtype. The separation of invasive encapsulated follicular variants from PTCs implies that differential diagnosis between IEFVPTC and IFVPTC can be difficult. We performed a gene expression analysis by NanoString technology on 23 PTCs, divided into 11 IEFVPTCs and 12 IFVPTCs. We focused our attention on the possible role of the tumor microenvironment (TME) and, in particular, the role of the extracellular matrix (ECM). IFVPTC, compared to IEFVPTC, showed a statistically significant downregulation of 2 genes and an upregulation of 45. Among these genes, we focused our attention on TIMP2 and COL1A2, whose high upregulation was statistically significant in IFVPTC. TIMP2 and COL1A2 are involved in ECM degradation and synthesis and in collagen biosynthesis and modification. The ECM and collagen alterations in IFVPTC could reflect the different tumor behavior of FVPTCs, allowing the identification of new biomarkers to distinguish IEFVPTC from IFVPTC.