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case_images: Radiological findings. (A, B) Contrast-enhanced chest CT showing a mass in the right lower lung lobe; the red arrow indicating the tumor region. (C-E) 18F-FDG PET/CT showing FDG avidity and extent of the pulmonary tumoral sites
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case_images: Contrast-enhanced chest CT showed a 73 mm mass in the lower lobe of the right lung, accompanied by obstructive pneumonia in the right lung, cancer lymphangitis in the right lower lung, multiple metastases in the bilateral lungs, and possible right hilar lymph node metastasis ( Figures 1A, B ). 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) imaging showed intense uptake in a 66.2 mm soft tissue mass in the lower lobe of the right lung and 11.7 mm or 6.1 mm nodules in the upper lobes of the bilateral lungs and right hilar lymph nodes ( Figures 1C-E ).
case_images: Histological findings. (A) Primary lesion obtained from bronchoscopy showing a malignant tumor composed of large tumor cells with enlarged hyperchromatic nuclei and abundant eosinophilic cytoplasm (hematoxylin and eosin staining). (B) Immunohistochemical staining of the primary lesion showing a strong positive reaction for HCG. (C) Immunohistochemical staining for PD-L1 revealing 70% positive cells. (D) Immunohistochemical staining for CK-pan (AE1/AE3) showing strong positivity. (E) Immunohistochemical staining for GATA-3 showing partial positivity. (F) Immunohistochemical staining for SALL4 showing partial positivity. Scale bar= 100mum.
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case_images: Our pathologist further analyzed the hematoxylin and eosin staining of the primary lesion and found that the malignant tumor consisted of multinucleated syncytiotrophoblasts, cytotrophoblasts, and intermediate trophoblasts ( Figure 2A ). The immunohistochemical results were as follows: TTF-1 (-), Napsin A (-), P63(partially +), P40(partially +), CK-pan(AE1/AE3)(+), BRG1(+, not missing), INSM1(-), CgA(-), Syn(-), Ki-67(+, 50%-60%), INI-1(+, not missing), NUT(-), PD-L1(22C3)(+, TPS=70%), SALL4(partially +), GATA-3(partially +), HCG(partially +), CD10(+), Inhibina(-), and P53(+, wild-type) ( Figure 2 ).
case_images: The change in serum HCG levels and chest CT finding. (A) The changes in serum HCG levels. (B) The timeline and changes in the lung mass and nodules revealed by chest CT. The start date of chemoimmunotherapy was 2023.11.06.
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case_images: Within 3 months of starting therapy, the patient's serum HCG dropped to 0.40 IU/L ( Figure 3A ). A chest CT scan showed a significant reduction in the mass in the right lung after 4 months ( Figure 3B ).