PMC4697920_01
CT from another hospital 2 years earlier shows a 3.2 x 2.4-cm lipomatous tumor at the left hilum adjacent to the left lower pulmonary vein.
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CT about 2 years earlier had shown a 3.2 x 2.4-cm lipomatous tumor at the left hilum adjacent to the left lower pulmonary vein (Fig. 1), and that lipomatous tumor was considered the origin of the present mediastinal tumor.
Contrast-enhanced CT of the chest shows an oval, smooth-shaped, heterogeneous tumor displacing the left lower lobe of the lung, measuring 10 x 7.4 x 6 cm on horizontal (A) and coronal (B) sections without pleural effusion or hemothorax.
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Contrast-enhanced CT performed in our hospital showed a heterogeneous tumor, displacing the left lower lobe of the lung, and measuring 10 x 7.4 x 6 cm on horizontal and coronal sections (Fig. 2A and B).
Chest X-ray from the first visit to our hospital (A), and 3 weeks after that initial visit (B). These photos show rapid growth of the left intrathoracic tumor.
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Chest radiography showed rapid growth of the left intrathoracic tumor (Fig. 3A and B), and CT revealed a tumor measuring 11.4 x 8 x 6.2 cm without pleural effusion or hemothorax.   
Gross appearance of the tumor. The well-circumscribed mass is encapsulated by fibrous tissue, showing a myxoid appearance intermingled with a whitish, solid part on the cut surface.
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RJV163F4
The cut surface revealed a myxoid appearance, partially intermingled with a whitish, solid part (Fig. 4).
Histopathological findings of the tumor. (A) Myxoid, pleomorphic component. (B) Well-differentiated liposarcoma component. Positive immunoreactions for CDK4 (C) and MDM2 (D) in the nuclei of tumor cells, confirming the diagnosis of dedifferentiated liposarcoma.
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The whitish, fibrous part comprised dense fibrous stroma containing scattered pleomorphic tumor cells and partially intermingled with mature fat tissue, showing features of well-differentiated liposarcoma (Fig. 5A and B).