case_images: PMC8761760_01
case_images: Time course of events after lung transplantation. 18F-FDG PET-CT, 18F-fluorodeoxyglucose PET-CT; PTNB, percutaneous transthoracic needle lung biopsies. Radiography images: 1) chest CT of March 2013, axial reconstruction pulmonary window: normal lung parenchyma. 2) Chest CT of March and September 2016, axial reconstruction pulmonary window: nodule in the upper right lobe. Axial reconstruction soft tissue window: normal liver parenchyma. 3) Chest CT of April 2017, axial reconstruction pulmonary window: two nodules at the left costodiaphragmatic sinus. Axial reconstruction soft tissue window: normal liver parenchyma. 4) Chest CT of April 2018, axial reconstruction pulmonary window: two nodules at the left costodiaphragmatic sinus; axial reconstruction soft tissue window: largest of two hypodense liver lesions with a diameter of 38 mm. 5) Chest CT of August 2018, axial reconstruction pulmonary window: two lung nodules have merged into one large lesion. Hepatic MRI, T2-weighted axial reconstruction: partly real increase in volume and partly due to intralesional bleeding. 6) Chest and abdominal CT of May 2019, axial reconstruction pulmonary and soft tissue window: significant decrease in volume of the lung and liver lesions after conversion to sirolimus. 7) MRI abdomen of November 2019, T2-weighted axial reconstruction: enlarged ovaries, especially the left one, with mixed solid tissue lesions. 8) CT abdomen of January 2020, axial reconstruction pulmonary window: volume increase of the lung lesion at the left costodiaphragmatic sinus; axial reconstruction soft tissue window: massive tumor progression of the liver lesions. 9) Chest and abdominal CT of October 2019, axial reconstruction pulmonary and soft tissue window: massive tumor progression of the lung and liver lesions. Large figures of the radiography can be found in the 
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case_images: In 2016, a 15-mm poly-lobular nodule was detected in the right upper lobe on routine chest CT ( Figure 1 , March 2016) without increased metabolism on 18F-fluorodeoxyglucose PET-CT (18F-FDG PET-CT), and further follow-up was provided. A slight increase to 20 mm was detected 6 months later, but again 18F-FDG PET-CT revealed no FDG avidity ( Figure 1 , September 2016). Follow-up CT 6 months later demonstrated two small nodules of 11 and 15 mm in the costodiaphragmatic sinus of the left lower lobe ( Figure 1 , April 2017), for which a conservative approach was adopted. However, a gradual volume increase was observed after 6 and 12 months, and two additional hypodense liver lesions appeared, the largest with a diameter of 38 mm ( Figure 1 , April 2018). 18F-FDG PET-CT again demonstrated no local hypermetabolism in either the lung or liver lesions. However, a concurrent further increase of the lung lesions was noted ( Figure 1 , August 2018). Consecutive CT scans showed a significant volume decrease of the lung and liver lesions over the next 9 months ( Figure 1 , May 2019). MRI demonstrated mixed solid tissue lesions with a preference for benign vascular lesions, but re-evaluation 6 months later revealed a further volume increase ( Figure 1 , November 2019). Two weeks postoperatively, because of severe right upper quadrant abdominal pain, massive hepatic tumor progression was observed ( Figure 1 , January 2020), as well as bone metastases, for which systemic treatment with paclitaxel (80 mg/m2) was initiated.
case_images: Histology images of donor and recipient lesions. (A) Histology image of donor brain lesion: irregular thin-walled vascular spaces, delineated by a flattened endothelium (blue asterisk). The vessels are embedded in gliotic tissue (yellow asterisk). (B-D) Lung lesion (recipient, September 2016). (B) Low power view of the lung lesion, showing the transition from the lung tissue (left, black arrow) to the vascular lesion (right, red arrow). (C) Dilated blood-filled spaces (yellow arrows), delineated by a normal flat endothelium (blue arrows). (D) CD31 stain (brown) confirms that the spaces are lined by endothelium. (E-G) Ovarian lesion (recipient, January 2020). (E) Transition from ovary cortical tissue (left, black arrow) to vascular lesion (right, red arrow). (F) Irregular vascular spaces delineated by hyperchromatic, atypical endothelial cells with numerous mitoses (circles). (G) CD31 stain (brown) shows the lesion's chaotic architecture.
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case_images: Microscopically, the tumors were consistent with vascular lesions with clear focal atypia, piling of nuclei, and excessive mitotic figures; were positive for vascular markers (CD31 and CD34); and had a local absence of alpha-smooth muscle actin ( Figure 2 ).