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case_images: Imaging of tumour lesions at baseline (A-F). (A) Pulmonary lesions under the lung window. (B) Pulmonary lesions under the mediastinum window (measuring 4.8cm x 4.6cm x 6.1cm). (C) Lymph node metastatic lesions under the mediastinum window. (D) Metastatic lesions in both lungs under the lung window. (E) Brain metastases under the coronal plane. (F) Brain metastases under the sagittal plane.
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case_images: After admission, the patient underwent a lung computed tomography (CT) examination, which revealed a mass-like high-density shadow of about 4.8x4.6x6.1 cm in the upper lobe of the left lung ( Figures 1A, B ), considering peripheral lung cancer; enlarged lymph node shadow in the mediastinum ( Figure 1C ), considering metastatic cancer; nodular high-density shadow in both lungs ( Figure 1D ), considering metastatic cancer. A (-), P40 (-), Vimentin (+), CK-pan (+), TTF-1 (+) ( Figure 2 ). A head magnetic resonance imaging (MRI) performed for a systematic evaluation suggested abnormal signal in the right parietal lobe ( Figures 1E, F ), and metastases were considered.
case_images: Lung tissue sections stained with hematoxylin-e.
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case_images: A (-), P40 (-), Vimentin (+), CK-pan (+), TTF-1 (+) ( Figure 2 ). A head magnetic resonance imaging (MRI) performed for a systematic evaluation suggested abnormal signal in the right parietal lobe ( Figures 1E, F ), and metastases were considered.
case_images: Imaging after anti-tumour therapy (A-K). (A, B): Significant increase in lung lesions and bilateral lung metastases after 1 course of pemetrexed in combination with carboplatin (measuring 5.5cm x5.7cm x7.1cm). (C-E): The second line of treatment was "albumin paclitaxel + nedaplatin + PD-1 inhibitor (Sintilimab)", and the lung lesions and metastases were significantly reduced after 2 courses (measuring 3.3cm x2.8cm x4.6cm). The efficacy assessment reached PR. (F, G): Significant reduction of brain metastases after 2 courses of Sintilimab in combination with chemotherapy. (H, I): The lung lesions continue to shrink after 4 courses of Sintilimab in combination with chemotherapy (measuring 2.8cm x 2.4cm x 3.9cm). (J, K): Brain metastases barely detectable after 4 courses of Sintilimab in combination with chemotherapy.
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case_images: After one cycle of chemotherapy with "pemetrexed + carboplatin", a repeat lung CT showed that the lung lesions, lymph nodes and bilateral lung metastases were larger than before ( Figures 3A   , B ). The second line of treatment was "albumin paclitaxel + nedaplatin + PD-1 inhibitor (Sintilimab)", and the lung lesions ( Figures 3C   , D ) and metastases ( Figures 3E   -G ) were significantly reduced after 2 cycles. The efficacy was assessed as maintenance PR ( Figures 3H-K ).
case_images: Changes in laboratory indicators during the onset of immune-related toxicity in patients (A, B). (A): Changes in IL-6 (Day0 represents the level after 0 days of steroid treatment; Day1 represents the level after 1 days of steroid treatment; Day3 represents the level after 3 days of steroid treatment; Day10 represents the level after 10 days of steroid treatment; Day21 represents the level after 21 days of steroid treatment.) (B) Changes in cardiac parameters (Day0 represents levels after 0 day of steroid treatment; Day1 represents levels after 1 day of steroid treatment; Day3 represents levels after 3 days of steroid treatment; Day4 represents levels after 4 days of steroid treatment; Day5 represents levels after 5 days of steroid treatment; Day8 represents levels after 8 days of steroid treatment).
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case_images: Bone marrow evaluation showed poor maturation of megakaryocytes.
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case_images: B ). Furthermore, on day 3 of hospitalization, the patient again developed thrombocytopenia with a minimum value of 41X10^9/L. Bone marrow evaluation ( Figure 5 ) showed poor maturation of megakaryocytes, and immune-associated thrombocytopenia was considered.
case_images: Platelet changes during the course of the disease (A-C). (A): Reduced platelet levels after 5 courses of chemotherapy combined with immunotherapy, with gradual recovery after symptomatic treatment. (B): Platelet levels decreased again after 1 course of immune consolidation therapy. (C): After discharge from hospital, oral steroids were administered and platelets recovered and maintained in the normal range.
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case_images: His platelets returned to normal on December 12,2020 (changes in platelet levels are shown in  Figure 6 ).
case_images: Regular imaging at follow-up, tumour lesions continue to shrink, efficacy maintained at PR (A-D). (A, B): On 7 March 2020, a lung CT scan revealed almost no tumour lesions. (C, D): On 3 October 2020, a lung CT scan revealed almost no tumour lesions.
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case_images: Regular imaging examinations were performed, the tumor lesions continued to shrink, and the efficacy maintained at PR ( Figure 7 ).
case_images: A summary of a clinical course.
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case_images: Table 1 . The clinical course of this patient is summarized in  Figure 8 .