Case Report: a hypermetabolic mediastinal mass (SUVmax 16.7) mimicking malignancy with spontaneous resolution: an inflammatory myofibroblastic proliferation and diagnostic pitfall

Diagnostic Pitfall of 18F-FDG PET/CT: Unifocal Nonbacterial Osteomyelitis Mimicking Bone Metastasis.

Chronic nonbacterial osteomyelitis (CNO) is a rare inflammatory bone disorder of unclear etiology that may present with unifocal or multifocal lesions. Because it can mimic malignancy on imaging, clinicoradiologic correlation and a multidisciplinary approach are essential. We report unifocal inflammatory osteitis compatible with CNO involving the sternum in a 56-y-old woman with a history of ductal carcinoma in situ. During surveillance, bone scintigraphy showed focal 99mTc-methylene diphosphonate uptake and 18F-FDG PET/CT revealed a solitary 18F-FDG-avid sternal lesion. MRI findings were suggestive of osteomyelitis. Biopsy excluded malignancy, supporting a diagnosis of CNO. Follow-up MRI demonstrated regression. This case underscores that a solitary 18F-FDG-avid sternal lesion does not necessarily represent metastatic disease, and histopathologic confirmation may prevent unnecessary treatment escalation.

Multisystem FDG-avid lesions mimicking malignancy in a teenager with hyper-IgE syndrome: A case study with literature review

Hyper-IgE Syndrome (HIES) is a rare immunodeficiency predisposing patients to infections, inflammation, and occasional neoplasia. We report a 17-year-old boy with HIES who presented with severe right thigh pain. FDG-PET/CT demonstrated a right adrenal mass (SUVmax=5.4), multiple pulmonary nodules, and a lytic-sclerotic femoral lesion (SUVmax=4.6), initially suggesting disseminated malignancy. Biopsy confirmed acute osteomyelitis and a benign spindle cell tumor of the adrenal gland. Two months later, persistent fever and elevated ESR prompted re-evaluation, revealing intense FDG uptake in the thoracic aorta (SUVmax=20.5) consistent with large vessel vasculitis, later confirmed by angiography. The combination of infection, benign tumor, and vasculitis illustrates the broad FDG uptake spectrum in HIES and the risk of misdiagnosis as malignancy. Integration of clinical, imaging, and histopathologic data was critical for accurate diagnosis. This case highlights FDG-PET/CT’s value in detecting inflammatory vascular disease and monitoring therapy, while reinforcing the importance of biopsy for definitive diagnosis. In immunodeficient patients, a multimodal diagnostic approach is essential to distinguish between malignant and benign FDG-avid lesions.

First Reported Pediatric Bladder Inflammatory Myofibroblastic Tumor (IMT) Evaluated and Staged with VI-RADS: CT and MR Findings.

INTRODUCTION Inflammatory Myofibroblastic Tumor (IMT) is a rare intermediate softtissue neoplasm that can arise in virtually any organ, including the urinary bladder. Accurate diagnosis is challenging but crucial, as conservative treatment approaches may be feasible. CASE PRESENTATION An 11-year-old boy presented with dysuria and microscopic hematuria. Ultrasound and Computed Tomography (CT) revealed a bladder mass associated with right-sided ureterohydronephrosis. Multiparametric Magnetic Resonance Imaging (mpMRI), performed for local staging using the Vesical Imaging Reporting and Data System (VI-RADS), demonstrated moderate diffusion restriction of the lesion on Diffusion-Weighted Imaging (DWI). However, the extent of bladder wall invasion was not clearly defined. Dynamic Contrast-Enhanced (DCE) T1-weighted SPIR sequences showed disruption of the hypointense muscularis propria with early extension into the ureteral wall at the intramural segment. Histopathological examination of biopsy specimens confirmed an inflammatory myofibroblastic tumor with muscular layer involvement. The patient received five months of chemotherapy with methotrexate and vinblastine, followed by partial cystectomy and ureteral reimplantation. Three years after treatment, follow-up MRI demonstrated no evidence of locoregional recurrence, indicating a complete response. CONCLUSION In this rare case of pediatric bladder IMT, MRI proved valuable for assessing locoregional tumor extent, guiding surgical planning, and evaluating treatment response. In particular, the case highlights the potential role of VI-RADS-based assessment in the staging and management of bladder IMT.

18 F-FDG and 68 Ga-FAPI PET/CT Imaging in a Patient with High-Grade Meningioma: A Case Report

Abstract High-grade meningiomas exhibit aggressive biological behavior and may benefit from functional imaging for further characterization. We report a 50-year-old female presenting with a 1-year history of intermittent right-sided headache and recurrent seizures. Contrast-enhanced magnetic resonance imaging demonstrated a well-defined extra-axial mass arising from the right sphenoid wing dura mater, accompanied by hyperostosis, dural tail sign, and vasogenic edema. 18 F-FDG and 68 Ga-FAPI PET/CT ( 68 Ga-fibroblast activation protein inhibitor positron emission tomography/computed tomography) were performed 1 week apart. FDG PET/CT demonstrated a tumor SUVmax of 7.08, comparable to the contralateral substantia nigra (SUVmax 7.27), resulting in limited lesion-to-background contrast (T/N ratio 0.97). In contrast, FAPI PET/CT showed tumor SUVmax of 3.02, with the aorta used as the background reference (SUVmean 1.76), yielding a tumor-to-background ratio of 1.71 and improved visual delineation due to minimal physiological brain uptake. Histopathology confirmed atypical meningioma (World Health Organization grade II). Although FAPI demonstrated higher tumor-to-background contrast than FDG, uptake remained relatively mild, suggesting predominant stromal mesenchymal involvement. Further comparative studies with established modalities such as somatostatin receptor PET are warranted.

Dual-time-point 18F-FDG PET/CT Imaging Unveiled Occult Hepatic Metastasis of Breast Cancer with N euroendocrine Differentiation: A Case Report

The Role of F-18 FDG PET/CT in the Evaluation of Solitary Pulmonary Nodules.

Objective Fluorine-18 fluorodeoxyglucose positronemissiontomography/computedtomography (F-18 FDG PET/CT) is commonly used in the evaluation of solitary pulmonary nodules (SPNs). This study aimed to investigate the predictive value of maximum standardized uptake value (SUVmax) and its ratios to liver and mediastinal blood pool SUVmax values for malignancy in SPNs, using histopathological findings as the reference standard. Methods The study included 130 patients who underwent F-18 FDG PET/CT and had either histopathological confirmation or at least two years of radiological follow-up. Demographic data (age and sex), nodule size, location, contour characteristics, nodule SUVmax, nodule-to-liver SUVmax ratio (NLR), and nodule-to-mediastinal blood pool SUVmax ratio (NBR) were recorded. Nodules were classified as benign or malignant based on histopathological results. Results Among the 83 patients with histopathological diagnosis, 54% (n = 44) had malignant lesions and 46% (n = 39) had benign lesions. The mean size of malignant nodules was approximately 20 mm. Receiver operating characteristic (ROC) analysis demonstrated that an SUVmax cutoff value of 4.02 provided the highest diagnostic accuracy for predicting malignancy. Both NLR and NBR showed significant diagnostic value in malignancy prediction. These parameters demonstrated high sensitivity (84-91%) and negative predictive value (76-84%), indicating their usefulness in excluding benign nodules. Conclusion The F-18 FDG PET/CT is a valuable imaging modality in the evaluation of solitary pulmonary nodules. In addition to SUVmax, the use of NLR and NBR may improve diagnostic accuracy and contribute to clinical decision-making.