PMC10364012_01
Chest CT on admission. Chest enhanced CT revealed the presence of an 85 mm x 60 mm mass occupying the anterior mediastinum and a right pleural effusion. The interior of the tumor was unreinforced and partially super-absorbed, showing necrosis and hemorrhaging. The tumor borders the right middle lobe (arrows) and pericardium (arrowheads), suggesting an invasion. The pleural effusion was 40 Hounsfield units, suggesting a hemorrhage within the tumor.
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Hounsfield unit (HU) was 40, suggesting hemorrhaging within the tumor (Figure 1). Hematological examinations revealed neutrophilic leukocytosis and elevated C-reactive protein levels.
Tumor pathology. The cut surfaces of a formalin-fixed specimen. The right lung was partially resected (arrows). Extensive hemorrhaging and fibrosis constituted the tumor (arrow dots). The tumor contained small amounts of solid components (arrowheads) (A). Microscopically, hematoxylin-eosin staining showed that epithelial cells and lymphocytes made up the tumor. The epithelial cells formed clusters (asterisk), suggesting a type B2 thymoma (B: x400). Epithelial cells were reticularly highlighted with cytokeratin AE1-AE3 immunostaining (C: x400), and the lymphocytes were highlighted with leukocyte common antigen immunostaining (D: x400). The thymic cyst wall was thick with fibrosis (*) and hemorrhaging (**) with hematoxylin-eosin staining (E: x40). A hemosiderosis was observed in the granulation tissue, indicating that bleeding and inflammation had repeatedly occurred within the tumor with hematoxylin-eosin staining (F: x200).
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The pathological diagnosis was a type B2 thymoma (World Health Organization 2020 classification), Masaoka Stage II, pT2N0M0 Stage II (Union for International Cancer Control eighth edition) (Figure 2).