PMC6010954_01
(A) Fluorine-18 Fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) axial fused slice shows an area of markedly increased FDG uptake involving the left sternoclavicular joint. Increased FDG uptake is demonstrated layering between the fascial planes of the left pectoralis muscles, with a focus of increased uptake extending posterior to the left sternoclavicular joint into the left anterior mediastinum. (B) Non-contrast axial slice at the same level as A, demonstrates increased subcutaneous fat stranding in the anterior left chest. The left chest pacemaker is partially visualized. (C) Axial PET slice at the same level as A and B highlights the hypermetabolic uptake with high maximum standardized uptake value (SUVmax 6). (D) Coronal CT slice centered at the left sternoclavicular joint shows subtle lobulated abnormalities in the region of the left sternoclavicular joint (arrow) and the left anterior mediastinum (arrowhead). The left chest pacemaker wires are partially visualized in the right atrium and ventricle. (E) Coronal fused F-18 PET/CT slice shows extensive increased FDG uptake centered at and around the left sternoclavicular joint with linear involvement at the left pectoralis myofascial plane. Also seen are areas of peripheral increased uptake and central photopenia in the inferior left sternocleidomastoid muscle (arrow) and the left anterior mediastinum (arrowhead). (F) Coronal PET slice highlights the fluid collections each with an FDG-avid rim and central photopenia consistent with abscess formation. (G) Maximum intensity projection (MIP) PET image of the whole body shows the findings highlighted above in the left sternoclavicular region. The patient's urinary system's dilation is a chronic finding. Mild increase in FDG uptake at the right anterior thigh is postsurgical in nature. Incidental note is made of a tiny focus of increased uptake in the region of the left parotid gland, likely benign.
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On admission day 3 the patient underwent 18F-FDG PET-CT (Fig. 1) in continuation of his staging work-up for sarcoma. Associated fluid collections were visible in the SCM and along the mediastinal pleuropericardial reflection, consistent with septic arthritis and abscess (Fig. 1A-F).