Immunohistochemical staining of the SFTPs. (A) Positive staining of CD34 was observed especially in the vascular endothelial cells and tumor cells (200). (B) Positive staining for CD34 in a malignant SFTP (200). (C) Strong positive expression of Bcl-2 was observed in the cytoplasm of tumor cells (200). (D) Positive staining of Bcl-2 in a malignant SFTP (200). (E) Ki-67 LI is about 5% in a benign SFTP (200). (F) A malignant case in which the Ki-67 LI is about 15% (200).