Branchioma is an uncommon benign neoplasm with an adult male predominance, typically occurring in the lower neck region. Different names have been used for this entity in the past (ectopic hamartomatous thymoma, branchial anlage mixed tumor, thymic anlage tumor, biphenotypic branchioma), but currently, the term branchioma has been widely accepted. Branchioma is composed of endodermal and mesodermal lineage derivatives, in particular epithelial islands, spindle cells, and mature adipose tissue without preexistent thymic tissue or evidence of thymic differentiation. Twenty-three branchiomas were evaluated morphologically. Eighteen cases with sufficient tissue were assessed by immunohistochemistry, next-generation sequencing (NGS) using the Illumina Oncology TS500 panel, and fluorescence in situ hybridization (FISH) using an RB1 dual-color probe. All cases showed a biphasic morphology of epithelial and spindle cells with intermingled fatty tissue. Carcinoma arising in branchioma was detected in three cases. The neoplastic cells showed strong AE1/3 immunolabeling (100%), while the spindle cells expressed CD34, p63, and SMA (100%); AR was detected in 40-100% of nuclei (mean, 47%) in 14 cases. Rb1 showed nuclear loss in ≥ 95% of neoplastic cells in 16 cases (89%), while two cases revealed retained expression in 10-20% of tumor cell nuclei. NGS revealed a variable spectrum of likely pathogenic variants (n = 5) or variants of unknown clinical significance (n = 6). Loss of Rb1 was detected by FISH in two cases. Recent developments support branchioma as a true neoplasm, most likely derived from the rudimental embryological structures of endoderm and mesoderm. Frequent Rb1 loss by immunohistochemistry and heterozygous deletion by FISH is a real pitfall and potential confusion with other Rb1-deficient head and neck neoplasms (i.e., spindle cell lipoma), especially in small biopsy specimens.

• MeSH
• branchiom * patologie   MeSH
• dospělí MeSH
• hybridizace in situ fluorescenční MeSH
• lidé MeSH
• molekulární biologie MeSH
• nádory brzlíku * MeSH
• nádory glandulární a epitelové * MeSH
• nádory měkkých tkání * patologie   MeSH
• nádory sítnice * MeSH
• retinoblastom * genetika   patologie   MeSH
• thymom * MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Sinonasal mucosal melanoma is a rare tumor arising within the nasal cavity, paranasal sinuses, or nasopharynx (sinonasal tract). This study evaluated 90 cases diagnosed in 29 males and 61 females with median age 68 years. Most tumors involved the nasal cavity and had an epithelioid morphology. Spectrum of research techniques used in this analysis includes targeted-DNA and -RNA next-generation sequencing, Sanger sequencing, fluorescence in situ hybridization and immunohistochemistry. Sinonasal melanomas were commonly driven by RAS (38/90, 42%), especially NRAS (n = 36) mutations and rarely (4/90, 4%) displayed BRAF pathogenic variants. BRAF/RAS mutants were more frequent among paranasal sinuses (10/14, 71%) than nasal (26/64, 41%) tumors. BRAF/RAS-wild type tumors occasionally harbored alterations of the key components and regulators of Ras-MAPK signaling pathway: NF1 mutations (1/17, 6%) or NF1 locus deletions (1/25, 4%), SPRED1 (3/25, 12%), PIK3CA (3/50, 6%), PTEN (4/50, 8%) and mTOR (1/50, 2%) mutations. These mutations often occurred in a mutually exclusive manner. In several tumors some of which were NRAS mutants, TP53 was deleted (6/48, 13%) and/or mutated (5/90, 6%). Variable nuclear accumulation of TP53, mirrored by elevated nuclear MDM2 expression was seen in >50% of cases. Furthermore, sinonasal melanomas (n = 7) including RAS/BRAF-wild type tumors (n = 5) harbored alterations of the key components and regulators of canonical WNT-pathway: APC (4/90, 4%), CTNNB1 (3/90, 3%) and AMER1 (1/90, 1%). Both, TERT promoter mutations (5/53, 9%) and fusions (2/40, 5%) were identified. The latter occurred in BRAF/RAS-wild type tumors. No oncogenic fusion gene transcripts previously reported in cutaneous melanomas were detected. Eight tumors including 7 BRAF/RAS-wild type cases expressed ADCK4::NUMBL cis-fusion transcripts. In summary, this study documented mutational activation of NRAS and other key components and regulators of Ras-MAPK signaling pathway such as SPRED1 in a majority of sinonasal melanomas.

• MeSH
• fosfatidylinositol-3-kinasy třídy I genetika   MeSH
• hybridizace in situ fluorescenční MeSH
• lidé MeSH
• melanom * genetika   patologie   MeSH
• molekulární biologie MeSH
• mutace MeSH
• mutační analýza DNA MeSH
• nádory vedlejších dutin nosních * genetika   patologie   MeSH
• paranazální dutiny * patologie   MeSH
• protoonkogenní proteiny B-raf genetika   MeSH
• RNA MeSH
• senioři MeSH
• signální transdukce MeSH
• TOR serin-threoninkinasy genetika   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH