Cutaneous melanoma (CM) is traditionally considered one of the most “immunogenic” tumors, eliciting a high immune response. However, despite the presence of tumor-infiltrating lymphocytes (TILs), melanoma cells use strategies to suppress antitumor immunity and avoid being eliminated by immune surveillance. The PD-1 (programmed death-1)/PD-L1 (programmed death-ligand 1) axis is a well-known immune escape system adopted by neoplastic cells. Therefore, immunotherapy with PD-1 and PD-L1 inhibitors is quickly becoming the main treatment approach for metastatic melanoma patients. However, the clinical utility of PD-L1 expression assessment in CM is controversial, and the interpretation of PD-L1 scores in clinical practice is still a matter of debate. Nonetheless, the recent literature data show that by adopting specific PD-L1 assessment methods in melanoma samples, a correlation between the expression of such a biomarker and a positive response to PD-1-based immunotherapy can be seen. Our review aims to describe the state-of-the-art knowledge regarding the prognostic and predictive role of PD-L1 expression in CM while also referring to possible biological explanations for the variability in its expressions and related treatment responses.

Background/Objectives: Bladder cancer is a prevalent urinary system malignancy and urinary cytology is widely used for its screening and follow-up. A novel diagnostic tool called Bladder Epicheck^® (BE) is increasingly being used for monitoring the recurrence of non-muscle-invasive bladder cancer (NMIBC). The simultaneous use of BE and urinary cytology can increase the diagnostic performances in the follow-up of bladder neoplasms. Methods: In this multicenter study, we retrospectively evaluated the data of 322 patients in follow-up for a high-grade bladder carcinoma over a six-year period (from January 2018 to March 2024). The diagnostic performances of both cytology and BE and their combination were calculated using histology as gold standard. Results: Recurrences were diagnosed as high-grade urothelial carcinoma NMIBC in 18 cases, low-grade papillary NMIBC in 8 cases, and carcinoma in situ (CIS) in 4 cases. Cytological analysis correctly identified 26 out of 30 carcinomas, while 286 were correctly diagnosed as negative results. BE correctly identified 25 out of 30 carcinomas, 285 were correctly diagnosed as negative results. The combination of BE and urinary cytology correctly identified 29 out of 30 carcinomas, while 289 were correctly diagnosed as negative results. Conclusions: The combination of BE and cytology could be the most effective approach for follow-up diagnosis in patients with high-grade NMIBC, reducing unnecessary invasive procedures.

Thyroid nodules are a common, benign condition with a higher prevalence in women, individuals with iodine deficiency, and radiation exposure. Treatment options for benign thyroid nodules include pharmaceutical therapy, thyroidectomy, and thermal ablation (TA). TA, including laser ablation (LA), radiofrequency ablation (RFA), and microwave ablation (MWA), is a procedure that uses heat to cause tissue necrosis. It is commonly used for large, firm, benign, non-functioning thyroid nodules that cause severe symptoms or pain when surgery is not recommended or desired. When thyroid nodules do not respond to TA, they undergo surgery to resolve the symptoms and clarify the diagnosis. This study aims to analyze the histological alterations found in surgically excised TA-treated thyroid nodules and to evaluate the morphological criteria of differential diagnosis between benign and malignant nodules, establishing whether the alterations observed on the histological sample are a consequence of TA or indicative of neoplastic disease. For this purpose, the adoption of ancillary methods, such as immunohistochemistry, is fundamental to distinguish the artifacts induced by TA from the typical morphological characteristics of malignant neoplasms.

Thermal ablation (TA) is an increasingly adopted minimally invasive treatment for benign thyroid nodules. However, TA induces marked histological alterations that may simulate thyroid malignancy, creating significant diagnostic pitfalls for pathologists. The present study expands our previous institutional series and further characterizes the morphologic, immunohistochemical, and molecular features of thermally ablated thyroid nodules in order to refine the differential diagnosis with thyroid carcinoma. Fourteen surgically excised thyroid nodules previously treated with laser thermal ablation were retrospectively analyzed. Histopathological evaluation focused on architectural changes, nuclear atypia, capsule alterations, degenerative phenomena, and evidence of invasion. Immunohistochemical analysis included galectin-3 (Gal-3), HBME-1, BRAF V600E, p53, and Ki-67. In addition, molecular profiling for the principal thyroid cancer-related alterations, including BRAF, RAS family genes, TERT promoter mutations, PIK3CA alterations, and RET rearrangements, was performed using targeted next-generation sequencing. All nodules showed treatment-related reactive and degenerative changes, including fibrosis/sclerosis, subcapsular hemorrhage, focal oncocytic metaplasia, and architectural distortion. No true capsular or vascular invasion was identified. Immunohistochemically, all cases were negative for Gal-3 and BRAF V600E, while HBME-1 expression was absent or only focally weak. Ki-67 proliferative activity remained consistently low (<3%) in all cases. Molecular analyses did not identify pathogenic alterations involving BRAF, RAS, TERT promoter, PIK3CA, or RET genes in any case. Thermal ablation induces reproducible reactive and degenerative histologic alterations that may closely mimic follicular or papillary thyroid neoplasms. The absence of malignancy-associated immunohistochemical and molecular alterations strongly supports the benign nature of these lesions and highlights the importance of an integrated morphologic, immunohistochemical, and molecular diagnostic approach in challenging post-ablation specimens. Thermally ablated thyroid nodules may display significant pseudo-neoplastic changes that can lead to overdiagnosis of carcinoma. Awareness of these treatment-related alterations, combined with immunohistochemical and molecular profiling, represents a reliable strategy to distinguish reactive post-ablation changes from true thyroid malignancy and to avoid inappropriate clinical management.