CASE REPORT: Herein, we describe and compare three cases of CASTLE, including a case with distant metastasis despite administering postoperative chemotherapy. Thus, the mechanisms underlying metastasis of CASTLE are unclear. This case study helps to elucidate the histopathological risk factors of metastasis in CASTLE.
DISCUSSION: We found that prominent lymphovascular invasion and higher proliferative activities might be risk factors of metastasis in CASTLE. In addition, we have summarised the cytological, morphological, and immunohistochemical features of CASTLE for an accurate diagnosis.