case_images: PMC6354677_01
case_images: Imaging showing anterior mediastinal mass 4 years after a type A aortic dissection. Axial (top left) and sagittal (right) chest CT images of the large (6.0 x 3.2 x 12.8 cm3) heterogeneous collection in the right prevascular space anterior to the ascending aorta initially concerning for a rupture but contained hematoma. MRI depicting the same heterogenous soft tissue mass (bottom left). Of note, no mass was detected on the chest CT scan performed 4 years prior (not shown).
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case_images: This revealed a heterogeneous collection in the right prevascular space immediately anterior to the ascending aorta measuring 6.0 x 3.2 x 12.8 cm3, concerning for aortic rupture with contained hematoma (Fig. 1, top left and right). CT-guided biopsies of the soft tissue mass were non-diagnostic. Cardiac MRI was unable to conclusively characterize the lesion (Fig. 1, bottom left).
case_images: Operative approach.
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case_images: Operative planning involved concerns that this may indeed have been a malignant lesion with hemorrhagic transformation or a complication related to the aortic graft, such as infected hematoma or chronic inflammation (Fig. 2).
case_images: Intraoperative images showing location of lesion and final resected specimen. Intraoperatively, the mass was found to be overlying but densely adherent to the aorta (left). The mass was completely resected with an intact capsule; lesion in situ (middle) and resected specimen (right).
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case_images: Intraoperatively, the mass was found to overly and densely adhere to the aorta (Fig. 3, left and middle). Final pathology revealed a large multilocular thymic cyst with evidence of cyst rupture, hemorrhage and organizing hematoma but no evidence of malignancy (Fig. 3, right).