case_images: PMC10036817_01
case_images: Enhanced chest CT scans of the patient during neoadjuvant therapy. (A) Baseline imaging demonstrating a 93 mm x 70 mm abnormal lung mass (red arrows) in the lower lobe of the left lung. (B) After 210 days of osimertinib therapy, the chest CT scan shows mass shrinkage (blue arrows) to 48 x 44 mm, achieving a partial response (PR). (C) After two cycles (42 days) of osimertinib and chemotherapy, the chest CT scan shows mass shrinkage (green arrows) to 40 mm x 37 mm, achieving a sustained partial response (sPR). CT, computed tomography.
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case_images: Enhanced chest CT showed occupation of the left lower lung (approximately 93 mm x 70 mm), with no obvious enlargement of the mediastinal lymph nodes ( Figure 1A ). Electronic bronchoscopy revealed an external pressure stenosis of the basal branch of the lower lobe of the left lung. Based on enhanced chest CT, the tumor in the left lower lung was significantly reduced ( Figure 1B ). On October 7, 2022, an enhanced chest CT scan showed progressive tumor shrinkage in the left lower lung, exhibiting a size of approximately 40 mm x 37 mm ( Figure 1C ).
case_images: Pathological diagnosis. (A, B) Pathological diagnosis of the lung biopsy revealing a moderately differentiated lung adenocarcinoma. Immunohistochemistry results are presented as follows: TTF-1(+), Napsin A (+), CK7 (+), CK5/6 (-), P40 (-), Ki67 (50%+), Syn (-), and CgA (-). (C-F) Pathological diagnosis of lung surgery is carcinosarcoma (adenocarcinoma accounts for approximately 40% and undifferentiated pleomorphic sarcoma accounts for approximately 60%) with a size of 40 mm x 33 mm x 26 mm, and the visceral pleura appears uninvolved. No tumor involvement can be observed in the bronchial stump, with no tumor metastasis in the lymph nodes of each group (-, 0/14). Immunohistochemistry outcomes were presented as follows: CK(pan)(partial+), Vimentin(partial+), TTF-1(partial+), CK7 (partial+), NapsinA (partial+), P40 (-), CK5/6 (-), Syn (-), CD56 (few+), S100 (-), SMA (-), Desmin (-), Calponin (-), MyoD1 (-), Myogenin (-), P53 (90%+), Ki67 (60%+), CD31 (partial +), ERG (Vascular +).
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case_images: Ultrasound-guided puncture biopsy of the left lower lung mass revealed moderately differentiated adenocarcinoma ( Figures 2A, B ). Postoperative pathological diagnosis was carcinosarcoma with marked necrosis, interstitial degeneration, inflammatory cell infiltration, cholesterol crystals, and small vascular hyperplasia ( Figures 2C-F ).
case_images: The 18F-FDG PET/CT examination (August 3, 2022). 18-FDG PET/CT shows robust 18-FDG uptake in the left lung mass (SUVmax: 27.998) with a size of 45 x 41 mm; no distant metastasis can be observed.
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case_images: Tumors version 1.1 (RECIST 1.1). Subsequent positron emission tomography (PET)-CT displayed a tumor in the left lower lung accompanied by increased glucose metabolism (SUVmax:27.998) and no other signs of metastasis ( Figure 3 ). There was no obvious abnormality on the enhanced brain
case_images: A summary of the treatment strategy employed in this patient.
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case_images: The process of clinical diagnosis and treatment for this patient is shown in  Figure 4 .