case_images: PMC9816999_01
case_images: Chest CT. (A) Chest CT showed multiple pulmonary nodules in right lung and masses in right pleura (arrows) three years after surgery. (B) Followed-up chest CT revealed that pulmonary nodules increased in number, and pleural masses increased in size (arrows) when first-line CDK4/6i + endocrine therapy was started.
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case_images: However, in January 2020, her chest CT showed multiple pulmonary nodules in right lung (the largest measuring 12.2 mm) andmasses in right pleura (the largest measuring 5.0 x 1.4 cm2) ( Figure 1A ). She developed mild cough and dyspnea in July 2020, and followed-up chest CT showed the progression of the pulmonary nodules and masses in the right pleura ( Figure 1B ), suggesting pulmonary and pleural metastases. 18F-FDG PET/CT showed multiple FDG avid pleural masses with maximum standardized uptake value (SUVmax) 9.4, and multiple pulmonary nodules with mild FDG uptake (SUVmax1.6), demonstrating pulmonary and pleural metastases ( Figure 2A ).
case_images: PET/CT. (A)
  18F-FDG PET/CT showed mild FDG uptake of the largest pulmonary nodule (arrow, SUVmax 1.6) and increased FDG uptake of the multiple pleural masses (arrows, SUVmax 9.4). (B) Followed-up 18F-FDG PET/CT showed mild FDG uptake of the largest pulmonary nodule (arrow, SUVmax 1.2) and increased FDG uptake of the multiple pleural masses (arrows, SUVmax7.0). (C) Pulmonary nodule was negative on 18F-FES PET/CT (arrow), and multiple pleural masses showed obvious FES uptake (arrows, SUVmax 5.0). (D) Pulmonary nodule was negative on followed-up 18F-FESPET/CT (arrow), and multiple pleural masses showed different levels of FES uptake (arrows, SUVmax3.8).
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case_images: She developed mild cough and dyspnea in July 2020, and followed-up chest CT showed the progression of the pulmonary nodules and masses in the right pleura ( Figure 1B ), suggesting pulmonary and pleural metastases. 18F-FDG PET/CT showed multiple FDG avid pleural masses with maximum standardized uptake value (SUVmax) 9.4, and multiple pulmonary nodules with mild FDG uptake (SUVmax1.6), demonstrating pulmonary and pleural metastases ( Figure 2A ). Two months later, 18F-FDG PET/CT was performed to evaluate the treatment response ( Figure 2B ), which revealed that both the pulmonary nodules and the pleural masses were smaller than that of chest CT in April 2021 (the largest pulmonary nodule measuring 9.6 mm, and the largest pleural mass measuring 4.0 x 1.2 cm2), and pleural effusion was decreased. To evaluate the ER status of metastatic lesions, 18F-FES PET/CT was performed subsequently ( Figure 2C ). The second 18F-FES PET/CT was performed and there was a new ER-positive pleural mass with SUVmax 2.7 and EEV 5.3 cm3 ( Figure 2D ), and the other pleural metastases decreased both in size and uptake of FES.
case_images: Timeline of the patient's disease progression.
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case_images: The timeline of the patient's disease progression was summarized in  Figure 3 .