FLCN and neoplasm: Analysis revealed that the tumor cells were immunopositive for vimentin, microphthalmia transcription factor (Fig. 3c), S100, CD1a (Fig. 3d), CD10 (Fig. 3e), CD63, and folliculin (Fig. 3f), but immunonegative for cytokeratin, α-smooth muscle actin, HMB45, Melan-A, and PNL-2.