case_images: PMC4854032_01
case_images: Noncontrast computed tomography scan of the chest showing a 2 cm round soft tissue mass with smooth regular margin in the left lower lobe
case_images: CJ-13-9-g001.jpg
case_images: PMC4854032_01_CJ-13-9-g001.jpg
case_images: F1
case_images: On CT scan, the nodule displayed low attenuation and focal areas of calcification [Figure 1].
case_images: Fibrotic stromal fragment with papillary features in a background of abundant blood (Papanicolaou stain, x100)
case_images: CJ-13-9-g002.jpg
case_images: PMC4854032_01_CJ-13-9-g002.jpg
case_images: F2
case_images: The second pass yielded moderately cellular smears composed of scattered large fibrotic tissue fragments, some with papillary configuration [Figure 2], in a background of abundant blood.
case_images: Fibrovascular fragment associated with round cells (Diff-Quik stain, x200)
case_images: CJ-13-9-g003.jpg
case_images: PMC4854032_01_CJ-13-9-g003.jpg
case_images: F3
case_images: Transgressing blood vessels were evident in many of these tissue fragments [Figure 3].
case_images: Cohesive sheets of surface cells arranged in pavement-like fashion (Diff-Quik stain, x400)
case_images: CJ-13-9-g004.jpg
case_images: PMC4854032_01_CJ-13-9-g004.jpg
case_images: F4
case_images: They were arranged in pavement-type pattern, resembling pneumocytes and not associated with fibrovascular structures [Figure 4].
case_images: Dense collagenous stromal tissue associated with bland appearing round cells (x200)
case_images: CJ-13-9-g005.jpg
case_images: PMC4854032_01_CJ-13-9-g005.jpg
case_images: F5
case_images: The third pass was hypocellular and revealed some fragments of dense collagenous tissue, some associated with round cells [Figure 5].
case_images: The papillary front on the cell block lined by a single layer of flat surface cells is focally hyalinized. Scattered round cells and inflammatory cells are observed in the center of this structure (H and E, x200)
case_images: CJ-13-9-g006.jpg
case_images: PMC4854032_01_CJ-13-9-g006.jpg
case_images: F6
case_images: These papillary fronts were lined with a single layer of small flat or low cuboidal cells [Figure 6].
case_images: Both surface and round cells are positive for thyroid transcription factor-1 immunostain (x200)
case_images: CJ-13-9-g007.jpg
case_images: PMC4854032_01_CJ-13-9-g007.jpg
case_images: F7
case_images: Both surface and round tumor cells were positive for thyroid transcription factor 1 (TTF-1) [Figure 7] and negative for synaptophysin and chromogranin.
case_images: AE1/AE3 immunoreactivity is present in the surface cells but not the round cells (x200)
case_images: CJ-13-9-g008.jpg
case_images: PMC4854032_01_CJ-13-9-g008.jpg
case_images: F8
case_images: AE1/AE3 and negative for progesterone receptor (PR), whereas the round cells within those papillary structures were negative for AE1/AE3 and positive for PR [Figures 8 and 9]. A proliferative index marker (Ki-67) showed staining in <3% of the tumor cells.
case_images: Progesterone receptor immunoreactivity is present in the round cells but not the surface cells (x200)
case_images: CJ-13-9-g009.jpg
case_images: PMC4854032_01_CJ-13-9-g009.jpg
case_images: F9
case_images: AE1/AE3 and negative for progesterone receptor (PR), whereas the round cells within those papillary structures were negative for AE1/AE3 and positive for PR [Figures 8 and 9]. A proliferative index marker (Ki-67) showed staining in <3% of the tumor cells.