CEACAM6 and lymphangioma: Our previous single‐cell RNA sequencing data of CSF circulating tumor cell (CSF‐CTCs) from five LUAD‐LM patients indicated that CEACAM6 mRNA was significantly upregulated compared to normal CSF cells (Figure 1A), and the immunohistochemistry staining also showed high expression of CEACAM6 in CSF‐CTCs (Figure 1B).