PMC8455843_01
CT, PET, and MRI scans showed a primary lesion in the right lung and metastatic tumors in mediastinum, right neck, and right liver. (A) The lung window of CT examination showed a round-like mass (arrow) in the medial segment of the right middle lobe with a smooth margin. (B) The lesions (arrow) were slightly enhanced, and the tortuous small vessel shadow was seen inside. (C,D) PET examination showed that the radioactivity uptake of the right pulmonary pericardial lesions was increased (C, arrow), and the suspected annular radioactivity uptake in the mediastinum (D, arrows) was increased. No obvious abnormal radioactivity uptake was seen in other organs. (E) The neck MRI showed metastatic tumors (arrow) in the right neck after 5 months of the operation (thoracoscopic assisted resection of the right middle lung and systemic lymphadenectomy). The lesion was uneven enhancement and had abundant necrotic areas. (F) The abdomen MRI showed a lesion in the left lateral lobe of the liver (arrow). CT, chest enhanced computed tomography; PET, positron-emission tomography; MRI, magnetic resonance imaging.
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Chest enhanced computed tomography (CT) scans confirmed a 6.5-cm pulmonary nodule in the right middle lobe (RML), with enlarged media stinal LN (Figures 1A,B). Positron-emission tomography (PET) showed increased uptake in the nodule and confirmed multiple media stinal LNs (Figures 1C,D), with no other areas of uptake. On February 2019, 3 months after the second operation, neck-enhanced magnetic resonance imaging (MRI) showed an enlarged right supraclavicular LN measuring 5.4 x 3.8 cm (Figure 1E). The abdominal enhanced MRI showed a 1.5 x 1.2 cm nodule in the upper left lobe of the liver (Figure 1F).
Histopathology of the primary pulmonary lesion in this unusual PSP case. (A) A large solid mass in the middle right lobe with relatively clear boundary and grayish-white, slightly tough texture cut surface. (B) The boundary between tumor and normal lung tissue was relatively clear, with the invasion of minor tumor nodules (arrow). (C) Solid cell area (star), papillary structure (asterisk) and sclerotic area (spot) in turn beneath normal lung tissue. (D) The migration of solid cell zone and papillary structures. (E) Papillary structures of different size (asterisk) covered with surface epithelial cells (arrow) appear in sclerotic background. (F) In the solid cell area, polygonal tumor cells were mainly diffusely arranged, certain atypia and giant tumor cells could be seen, but mitosis was hardly to be found. (G) Focal tumoral necrosis could be seen (star). CK (H), TTF-1 (I), and NapsinA (J) expressed in the same region as illustrated in this figure (E). P53 (K) and Ki-67 (L) expressed in the solid cell region and papillary structures as illustrated in this figure (F). (M) Double-labeling IHC showed the surface epithelial cells (black arrow) positive for CK7 and negative for PR, while the stromal-like cells (white arrow) in papilla's on the contrary. (N) Double labeling IHC showed CK7 and TTF-1 co-expressing in surface-lining cells (black arrow), while only TTF-1 positive in stromal-like cells (white arrow).Original magnification x 40 (B-E, G-M), original magnificationx100 (F,N). PSP, pulmonary sclerosing pneumocytoma; IHC, immunohistochemistry.
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A well-demarcated and circular mass, with grayish-white, slightly tough texture cut surface, was found in the RML (Figure 2A), 6 cm in diameter. Microscopically, the boundary between the tumor and the surrounding lung tissue was relatively clear except that a few minor infiltrative nodules were observed outside the main body of the tumor (Figure 2B). Solid cell area, papillary structure and sclerotic area composed of different proportion of surface epithelioid cells and polygonal stromal cells constituted the common mixed growth pattern of PSP (Figure 2C). Transition zone of solid and papillary pattern (Figure 2D), as well as the papillary structures in sclerosing background (Figure 2E) were observed, respectively. Focally in solid cell area, polygonal tumor cells distributed diffusely, with the increased cell density, and some pleomorphism and atypia appeared, but the mitosis was difficult to be found (Figure 2F). Focal tumor necrosis was noticed (Figure 2G). IHC analysis revealed that both the stromal cells and cuboidal surface cells showed positive for EMA and TTF-1 (Figure 2I), whereas only the surface cells expressed CK (Figure 2H), CEA, and Napsin A (Figure 2J). Most of the tumor cells were p53-positive (Figure 2K). The Ki-67 labeling index (LI) was about 5% (Figure 2L). Double-labeling IHC showed CK7 and TTF-1 positive but PR negative in surface-lining epithelial cells, while CK7 negative but TTF-1 and PR positive in polygonal stromal cells (Figures 2M,N).
Histopathological changes in metastatic lesions of this case. Tumors cells of mediastinal LNs (A,B) were positive for TTF-1 (C) and PR (D), but negative for NapsinA (C, red box). The Ki-67 LI was about 25% (E). The tumor cells of liver metastasis (F,G) were like the polygonal stromal cells in the primary pulmonary lesion, with obvious pleomorphism and atypia, and the mitosis is easily to be found (G). The tumor cells were positive for TTF-1 (H), PR (I), and P53 (J). LNs, lymph nodes; LI, labeling index.
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The histopathological and IHC staining of the resected specimens confirmed multiple organ metastasis of hilar, mediastinum (Figures 3A-E), cervical LNs, and liver (Figures 3F-J). TTF-1(Figures 3C,H), PR (Figures 3D,I) and p53 (Figure 3J), but negative for CK7 and Napsin A (Figure 3C, red box). The Ki-67 LI of mediastinum LNs (Figure 3E) and liver metastasis were higher than that of the primary lesion (25 vs. 5%).