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case_images: PET and brain MRI images at initial diagnosis. (A) Lung cancer is present in the hilar angle of the right lung before pembrolizumab treatment in November 2021. (B) Tissue biopsy showed squamous lung cancer.
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case_images: A 78-year-old man visited the authors' hospital complaining of chest tightness, cough, sputum, right back pain, and lower limb edema for 2 months; he was later diagnosed with squamous lung cancer of stage IVB (cT4N3M1) with brain metastasis ( Figure 1 ).
case_images: Timeline for absolute neutrophil count (ANC) with pembrolizumab administration. PEG-rhG-CSF, pegylated recombinant human granulocyte colony-stimulating factor; MPS, methylprednisolone.
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case_images: Adverse Events (CTCAE 5.0) was detected ( Figure 2 ). A complete blood count showed as follows: white blood cell: 500/mul, neutrophils: 0/mul, Hb: 10.7g/dl, and platelets: 19.7 x 104/mul ( Malignant tumor infiltration to bone marrow was not present ( Figure 4 ,  Table 2 ).
case_images: CT images before (A) and after administration of the first (B) and the second (C) dose with pembrolizumab. The tumor increased on CT.
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case_images: Table 1 ). The tumor progressed after pembrolizumab treatment per imaging evaluation ( Figure 3 ).
case_images: Bone marrow imaging. (A) Bone marrow cytological smear; there is no malignant tumor invasion into the bone marrow. (B) Bone marrow biopsy; the specimen shows agranulocytosis.
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case_images: Malignant tumor infiltration to bone marrow was not present ( Figure 4 ,  Table 2 ).