PMC6125801_01
Chest X-ray, on posterior-anterior (A) and lateral (B) views, demonstrates hilar-mediastinal enlargement with multiple nodular radiopacities in right hemithorax and pleural effusion on the same side.
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Abdomen Ultrasound (A and B) showed lobular and inhomogeneous masses in the right hemithorax with pleural effusion.
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As collateral findings, US confirmed the pleural effusion with multiple solid rounded masses at pulmonary bases (Fig. 2).
Chest Computed Tomography (CT) axial plane, on mediastinal windows, showing multiple masses in mediastinum and right pleura, with pleural free fluid, without displacement of mediastinal structures (A-B). No bronchial compression or atelectasis of lung is noted on lung window (C). After injection of iodinated contrast, the lesion appears hypo-vascular, with enhancing margins, internal lobulation and septation, and few calcific spots (D).
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The CT (Fig. 3), revealed a large mediastinal mass overrunning the right hemithorax, with pleural free fluid and multiple solid pleural masses on the right.
Positron Emission Tomography (PET) images show increased uptake of 18[F]-fluorodeoxyglucose in the parietal and mediastinal pleura of right lung (A-B). Chest and abdomen coronal section demonstrates no further uptakes suspicious for recurrences (C).
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During the hospitalization the patient underwent to 18 [F]-fluorodeoxyglucose (FDG)-PET (Fig. 4): the patient received intravenous injection of 18[F]-FDG (radioactivity: 371 m Bq) and rested for 45 min before PET-scan.
The first Region of Interest (ROI) positioned on anterior chest wall shows SUV 3,6 (A), the second one near the posterior cost-vertebral arch shows SUV 4,4 (B).
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Two Region of Interest (ROI) were positioned (Fig. 5): the first one on anterior chest wall (ROI 1: SUV 3,6), the second one near the posterior cost-vertebral arch (ROI 2: SUV 4,4) and maximum standardized uptake values were calculated.
Histopathological examination shows findings consistent with type B2 (cortical) thymoma. The hematoxylin and eosin stain with original magnification 2X (A), 10X (B) and 40X (C) show that the tumor is made up of epithelial cells and a high population of lymphocytic cells with bands of sclerosis. Note the neoplastic cells which are large and polygonal with high ratio nucleus/cytoplasm. The immunohistochemical with CD3 at magnification 20X (D) shows the presence of CD3, a co-receptor of T-cells that is first expressed in the cytoplasm of pro-thymocyte stem cells to whom raise thymus T-cells. It is also high specific marker of T-cells because it is expressed at each stage of development of T-cells. Note the high-density of the T-cells in the specimen. The immunohistochemical with Calretinin 20X (E), shows the presence of a monolayer of cells of pleural origin in close proximity with the population of lymphocytes of thymic origin. The immunostaining for pan-CK (AE1/AE3) at magnification 20X (F) is useful in demonstrating the epithelial origin or not of tumors, because these monoclonal antibodies bind with high affinity the human cytokeratin. Here CKAE1-AE3 shows the epithelial cells that made up mucoepidermoid carcinoma component.
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Histopathological examination (Fig. 6) revealed a tissue made-up by bands of sclerosis and average size lymphocytes with T-immature phenotype (precursor T cell, CD3+, CD5+/-, CD4+, CD8+, TdT+), associated also with irregular oval shape epithelial cells (CKAE1-AE3+, Calretinin-).