Pleomorphic adenoma (PA), the most prevalent salivary gland tumor, exhibits a diverse histological spectrum characterized by epithelial, myoepithelial, and mesenchymal patterns, and secretory products. However, a subset of PAs presents microscopic features suggestive of malignancy, leading to challenging and potentially significant diagnostic pitfalls. A comprehensive retrospective analysis was conducted on the Salivary Gland Tumor Registry, compiled by the authors. A total of 104 cases diagnosed between 1960 and 2023 were retrieved. Clinical findings, pathological features, and molecular genetic results were analyzed. In the study of 104 PA cases, 23 (22.1%) presented features suggestive of pseudoinvasion, with satellite nodules being the most common (43.5%) along with capsular penetration, irregular growth, pseudopodia, lipomatous changes, and vascular permeation. Features of pseudomalignant cytomorphology were found in 97 cases (93.3%), characterized by increased cellularity, cellular atypia, heightened proliferative activity, oncocytic metaplasia, and necrosis. Additionally, 30 cases (28.8%) displayed features resembling other defined malignant salivary gland tumors, particularly myoepithelial carcinoma, adenoid cystic carcinoma, and polymorphous adenocarcinoma. Despite PA's generally straightforward diagnosis, cases with these features may be mistakenly interpreted as malignant tumors. The shared morphocytological features underscore the complexity of an accurate diagnosis, emphasizing the need for meticulous examination and a comprehensive assessment, incorporating morphological, molecular, and immunohistochemical analyses to differentiate between benign and malignant salivary gland tumors, in selected cases.

• Klíčová slova
• Atypical, Mimic of malignancy, Pitfall, Pleomorphic adenoma, Salivary gland neoplasms,
• Publikační typ
• časopisecké články MeSH

Salivary gland carcinomas represent a heterogeneous group of poorly characterized head and neck tumors. The purpose of this study was to evaluate ALK gene and protein aberrations in a large, well-characterized cohort of these tumors. A total of 182 salivary gland carcinomas were tested for anaplastic lymphoma kinase (ALK) positivity by immunohistochemistry (IHC) using the cut-off of 10% positive cells. ALK positive tumors were subjected to FISH analysis and followed by hybrid capture-based next generation sequencing (NGS). Of the 182 tumors, 8 were ALK positive by IHC. Further analysis using hybrid capture NGS analysis revealed a novel MYO18A (Exon1-40)-ALK (exon 20-29) gene fusion in one case of intraductal carcinoma. Additional genomic analyses resulted in the detection of inactivating mutations in BRAF and TP53, as well as amplifications of ERBB2 and ALK. ALK rearrangements are a rare entity in salivary gland carcinomas. We identified a potentially targetable novel ALK fusion in an intraductal carcinoma of minor salivary glands.

• Klíčová slova
• Anaplastic lymphoma kinase, FISH, Immunohistochemistry, Intraductal carcinoma, Next generation sequencing, Salivary gland carcinoma,
• MeSH
• amplifikace genu MeSH
• anaplastická lymfomová kináza genetika   MeSH
• dítě MeSH
• dospělí MeSH
• fúze genů MeSH
• hybridizace in situ fluorescenční MeSH
• imunohistochemie MeSH
• intraduktální neinfiltrující karcinom enzymologie   genetika   patologie   MeSH
• karcinom enzymologie   genetika   patologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• nádorové biomarkery genetika   MeSH
• nádory slinných žláz enzymologie   genetika   patologie   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• vysoce účinné nukleotidové sekvenování MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ALK protein, human MeSH Prohlížeč
• anaplastická lymfomová kináza MeSH
• nádorové biomarkery MeSH