Hiroyuki Ozawa | Search PubMed

PubMed2026

Somatic-only SDHD variant with tumor-specific loss of heterozygosity in metastatic carotid body tumor: a case report with review of literature.

Carotid body tumors (CBTs) are rare paragangliomas in which genetic predisposition, particularly pathogenic variants in succinate dehydrogenase (SDHx) genes, plays an important role in tumorigenesis. Previous genetic studies of CBTs have primarily focused on germline SDHx variants, whereas somatic alterations remain poorly characterized. Among SDHx genes, SDHB variants are known to be associated with a higher metastatic risk, while SDHD variants are generally linked to a lower metastatic rate. We report the case of a 41-year-old man who presented with a painless right-sided neck mass. Imaging studies demonstrated a hypervascular tumor located at the carotid bifurcation with circumferential encasement of the carotid artery. During surgery, the tumor was classified as a Shamblin type III CBT, and complete surgical resection with vascular reconstruction was performed. Histopathological examination confirmed paraganglioma with metastasis to a single cervical lymph node. Germline genetic testing did not reveal any pathogenic variants. However, comprehensive tumor genomic profiling identified a somatic SDHD c.304C>G (p.His102Asp) variant accompanied by tumor-specific loss of heterozygosity (LOH) and copy-number loss at the SDHD locus, findings compatible with biallelic SDHD inactivation. The patient remained free of recurrence during follow-up. To our knowledge, this represents the first reported case of metastatic CBT harboring a somatic-only SDHD variant with tumor-specific LOH. This case suggests that reliance on germline testing alone may underestimate the molecular drivers of CBT and highlights the potential clinical value of tumor-based genomic profiling for risk stratification and prognostic assessment.

Carotid body tumor↗

PubMed2026

Radiomics as a spatial context for treatment decision-making in head and neck cancer.

Radiomics has been widely explored as a non-invasive biomarker in head and neck squamous cell carcinoma (HNSCC), yet its clinical role remains unclear. Tissue-based biomarkers differ in their susceptibility to spatial sampling. Biomarkers such as PD-L1 expression, immune-cell infiltration, necrosis, and immune exclusion may exhibit substantial spatial heterogeneity, whereas HPV/p16 status and some genomic alterations are generally more stable across the tumor. Nevertheless, localized sampling may incompletely capture heterogeneity in selected clinical contexts. This mismatch becomes clinically relevant when treatment decisions, particularly for chemoradiotherapy, immunotherapy, or de-escalation, are based on potentially non-representative biopsy findings. In this narrative review, we argue that the role of radiomics is not to outperform established biomarkers, but to contextualize them by capturing spatial heterogeneity related to hypoxia, necrosis, stromal architecture, and immune exclusion. We synthesize current evidence linking radiomic features to these biological processes and map them to specific clinical decision points, including larynx preservation, immunotherapy stratification, and recurrence assessment. Rather than serving as a standalone predictor, radiomics may provide complementary spatial information that helps identify situations in which biopsy-derived biomarkers should be interpreted with caution. Although current evidence is largely retrospective, radiomics offers a pragmatic framework for integrating spatial information into biomarker-guided clinical workflows.

Journal Article↗