Pathological findings. (A) The nodule is well-demarcated, hyalinized, and within the lung parenchyma (hematoxylin and eosin, ×40). (B) Variable-sized and irregularly shaped tumor cells with round to oval shape nucleus are located in the hyalinized stroma. Some of the neoplastic cells are rich in eosinophilic cytoplasm (×200). (C) There are characteristic intracytoplasmic vacuoles in the tumor cells (arrow; ×400). (D) The tumor cells are immunoreactive for CD31 in the cytoplasm (×400).