Fig. 6

Gross and histopathological findings. a Gross findings of the tumor. Size, 8 × 5.5 × 3.5 cm. The split surface shows a well-defined, internally heterogeneous, full-blown mass measuring 6 × 5.5 × 2.7 cm in size. The margins are yellowish white. b The tumor is located between the middle and lower lobes, and the lesion is composed of adipose tissue covered by a fibrous capsule. In the blue square, the upper right adipocyte is devoid of nuclei, i.e., necrotic. The sizes of the cells are generally well aligned (hematoxylin–eosin [HE] staining, scale bar: 200 μm). There was no morphologically discernible liposarcoma or malignant findings. Immunohistochemistry shows that MDM-2 was generally negative in adipocytes and cyclin-dependent kinase 4 was negative. c In the red square, elastic fibers are preserved, indicating that the lesion is within the fatty tissue between the middle and lower lobes, rather than infiltrating the lung (Elastica–Masson staining; scale bar: 300 μm)