Unveiling the Role of [18F]FDG PET/CT in NUT Carcinoma: Insights from a Case Series and Literature Review

Background: NUT carcinoma (NC) is a rare and highly aggressive NUTM1-rearranged malignancy characterized by rapid progression, frequent metastatic dissemination, and poor clinical outcomes. Evidence regarding the role of [18F]FDG PET/CT remains limited and is largely based on isolated case reports and small series. We describe serial [18F]FDG PET/CT findings in three pediatric and young-adult patients with NC and place these observations in the context of a structured narrative review of the available PET literature. Case Series and Methods: Three patients with histologically confirmed NC arising from the anterior chest wall, head and neck region, and mediastinal region underwent [18F]FDG PET/CT at baseline and during treatment or follow-up. All primary tumors were FDG-avid, although metabolic activity, disease distribution, treatment-related imaging changes, and clinical outcomes were markedly heterogeneous. Baseline PET/CT depicted FDG-avid primary, nodal, and distant disease; in one patient, skeletal lesions were identified without corresponding CT abnormalities, while in another, an additional skeletal PET finding prompted whole-body MRI evaluation. Serial PET/CT documented longitudinal changes in FDG uptake and disease distribution, without assigning formal metabolic response categories. The patient with localized disease remained alive and in complete clinical remission at 30 months, whereas the two patients with metastatic disease died 11 and 12 months after diagnosis, respectively. Baseline MTV and TLG showed substantial inter-patient variability and were explored only as descriptive quantitative measures of metabolically active disease burden. Conclusions: These observations illustrate the potential complementary contribution of [18F]FDG PET/CT to multimodality imaging in NUT carcinoma, particularly for whole-body disease depiction and assessment of longitudinal metabolic changes. MTV and TLG should be regarded as exploratory, method-dependent descriptive measures and are not validated biomarkers in NC. Larger multicenter studies using standardized acquisition, analysis, and longitudinal interpretation methods are required.