case_images: PMC10505615_01
case_images: Axial pre-contrast CT image (mediastinal window setting) (A) revealed a solitary well-defined soft-tissue mass in the size of 3cmx3 cmx3 cm, with some low-attenuation areas in the lower lobe of the left lung. Axial arterial phase CECT image (mediastinal window setting) showed a heterogeneous and obvious enhancement of the mass, with multiple focal areas of marked enhancement visible within the tumor (B). Axial venous phase CECT image (mediastinal window setting) showed further enhancement of the mass with irregular multiple focal low-attenuation areas internally (C). Axial lung window setting image showed a clear interface between the tumor and the lung, with unremarkable low-attenuation visible in the distal lung tissue (arrow) (D). The coronal CECT images in the mediastinal window setting (E) and lung window setting (F) showed that the tumor margin closely compressed the adjacent pulmonary artery and vein branch vessels.
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case_images: Pre-contrast CT image revealed a well-defined round soft-tissue mass in the lower lobe of the left lung, with a size of about 3 cm x 3 cm x 3 cm ( Figure 1A ). Multiple areas of marked enhancement of the lesion were observed within the tumor ( Figure 1B ). In the venous phase, the enhancement further increased with multiple foci of hyperenhancement ( Figure 1C ). Axial lung window setting image showed a clear interface between the tumor and the lung ( Figure 1D ). Coronal CECT images clearly depicted the relationship between the mass in the lung tissue and bronchovascular bundles ( Figures 1E, F ).
case_images: Axial in-phase T1WI image (A) and out-phase T1WI image (B) showed a round mass with iso-to-high SI compared with the thoracic muscle and mixed with some low SI foci within the mass. On the out-phase T1WI image, no areas of obvious signal reduction were found within the tumor compared to the in-phase T1-weighted image. On axial T2WI image (C), the tumor showed iso-to high SI with some small low SI foci, while on axial fat-suppressed T2WI image (D), the tumor showed a much higher SI. On axial DWI image (E) and ADC image (F), the mass showed a much higher SI, and the ADC value was (2.36 +- 0.22)x10-3mm2/s, suggesting that the mass was a benign tumor. DCE-MRI images (G) and corresponding time intensity curve of the SI (H) after intravenous injection of Gd-DTPA show early enhancement without obvious peak point, and subsequent plateau pattern.
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case_images: On the in-phase T1WI image, the mass presented iso-to-high signal intensity (SI) than that of muscle and mixed with some low-SI foci within the mass ( Figure 2A ). On the out-phase T1WI image, the mass still showed iso-to-higher SI with no areas of SI reduction within the tumor compared to the in-phase T1WI image ( Figure 2B ). On the T2WI image, the mass also presented iso-to-higher SI than that of muscle and with some small low SI foci ( Figure 2C ). On the fat-suppressed T2WI image, the mass exhibited heterogeneous signal intensity (SI), characterized by predominantly high SI with scattered regions of low SI within the tumor (Figure 2D). On the fat-suppressed T2WI image, the SI was not reduced and became relatively higher ( Figure 2D ). On the DWI image ( Figure 2E ) and the apparent diffusion coefficient (ADC) image ( Figure 2F ), the mass exhibited significant high SI and a measured ADC value of (2.36 +- 0.22) x 10-3 mm2/s. T1WI revealed noticeable marked heterogeneous progressive enhancement throughout the mass ( Figure 2G ). The mass showed early enhancement on DCE-MRI images without a significant peak, followed by a plateau pattern ( Figures 2G, H ).
case_images: Histopathology of the present case of PSP. It was composed of four major histologic patterns: (A) solid pattern (20%, Hematoxylin and eosin, x20), (B) papillary pattern (10%, Hematoxylin and eosin, x20), (C) sclerotic pattern (40%, Hematoxylin and eosin, x20), and (D) hemangiomatous pattern (30%, Hematoxylin and eosin, x20).
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case_images: Microscopically, the tumor was well-defined and composed of cuboidal surface cells and round stromal cells, with mixed multiple growth patterns and consisted of a solid pattern (20% of the total area,  Figure 3A ), a papillary pattern (10% of the total area,  Figure 3B ), a sclerotic pattern (40% of the total area,  Figure 3C ), and a hemangiomatous pattern (30% of the total area,  Figure 3D ).
case_images: Immunohistochemical results. Immunohistochemical staining (x20) showed that the cuboidal surface cells and round stromal cells the of the tissue are positive for thyroid transcription factor-1 (TTF-1) (A), epithelial membrane antigen (EMA) (B) and Vimentin (C). AE1/AE3 was positive in cuboidal surface cells but negative in round stromal cells (D), while progesterone-receptor (PR) exhibited a negative result in cuboidal surface cells but a positive result in round stromal cells (E). The Ki-67 index was below 2% (F).
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case_images: Immunohistochemically, thyroid transcription factor-1(TTF-1), epithelial membrane antigen (EMA), and Vimentin were positive for both cuboidal surface cells and round stromal cells ( Figures 4A-C ). AE1/AE3 was positive in cuboidal surface cells but negative in round stromal cells ( Figure 4D ), while progesterone-receptor (PR) exhibited a negative result in cuboidal surface cells but a positive result in round stromal cells ( Figure 4E ). Figure 4F ). Finally, the pathological and IHC findings of the tumor illustrated the final diagnosis of PSP.