case_images: PMC11695534_01
case_images: A-F Pathological findings of a nodule in the left lower lobe excised during thoracoscopic surgery and diagnosed as a PSP. G Pathological findings of dissected mediastinal and lower paratracheal lymph nodes during thoracotomy confirming PSP metastasis. A, B, and G Hematoxylin and eosin staining. C-F Immunostaining for EMA, TTF-1, CK AE1/AE3, and PD-L1. A, B Atypical round stromal cells with increased proliferation and pleomorphism compared to that of normal tissues. The surface and round cells are positive for (C) EMA and (D) TTF-1. The former exhibits diffuse positivity, and the latter is weakly positive for (E) CK AE1/AE3, while both are negative for (F) PD-L1. Except for image A, which was captured with a 100 x objective, all images were obtained using a 400 x objective lens. PSP pulmonary sclerosing pneumocytoma, EMA epithelial membrane antigen, TTF-1 thyroid transcription factor-1, PD-L1 programmed death-ligand 1; CK creatinine kinase
case_images: 13691_2024_737_Fig1_HTML.jpg
case_images: PMC11695534_01_13691_2024_737_Fig1_HTML.jpg
case_images: Fig1
case_images: The pathological analysis led to a diagnosis of PSP (Fig. 1A, B), as demonstrated by positive immunostaining for epithelial membrane antigen (EMA), thyroid transcription factor-1 (TTF-1), and cytokeratin (CK) AE1/AE3 (Fig. 1C-E), with prominent round stromal cell proliferation and pleomorphism compared to normal tissue. Thoracotomy with mediastinal and lower paratracheal lymph node dissection, followed by pathological examination, confirmed metastasis of PSP (Fig. 1G) with immunostaining patterns identical to those of the dissected nodule in the left lower lobe. TP53 mutations (R280T and E287K) with a low tumor mutation burden (3 muts/Mb). The tumor proportion score for programmed cell death ligand 1 (PD-L1) expression was less than 1%, as assessed using the 22C3 antibody (Fig. 1F).
case_images: A, B, E, and F Chest CT. C, D, G, H PET-CT. A-D reveal enlarged mediastinal lymph nodes and FDG uptake in the lymph nodes and sacrum, indicating recurrent PSP. E-F Images obtained after three immunotherapy cycles revealing reduced mediastinal lymph node size and FDG accumulation. CT computed tomography, PET-CT, positron emission tomography-computed tomography, FDG fluorodeoxyglucose, PSP, pulmonary sclerosing pneumocytoma
case_images: 13691_2024_737_Fig2_HTML.jpg
case_images: PMC11695534_01_13691_2024_737_Fig2_HTML.jpg
case_images: Fig2
case_images: PSP. PET-CT revealed renewed accumulation in the mediastinal lymph nodes, indicating PSP recurrence (Fig. 2A-D). This treatment regimen produced no significant adverse reactions and after three cycles, CT and PET-CT revealed a reduction in mediastinal lymph node size and FDG accumulation (Fig. 2E-H).