Solitary fibrous tumor of the pleura: morphogenesis and progression. A report of 36 cases

Purpose: We attempted to identify the exact point of tumor eruption of a solitary fibrous tumor of the pleura (SFTP). Methods: We morphologically classified 36 SFTPs into 5 categories. Type A showed a connection that included a bloodstream with the pleura on both sides. Type B only showed a connection that included a bloodstream with the visceral pleura, and had a non-bloodstream connection with the parietal pleura. Type C only showed a connection that included a bloodstream with the visceral pleura, and had no connection with the parietal pleura. Type D showed a non-bloodstream connection with the visceral pleura, and only showed a connection that included a bloodstream with the parietal pleura. Finally, type E had no connection with the visceral pleura, and only showed a connection that included a bloodstream with the parietal pleura. The clinicopathological profiles of the tumors were investigated according to their type. Results: The distribution of the 36 SFTPs was as follows: A (19 %), B (6 %), C (67 %), D (0 %) and E (8 %). The tumors categorized as type A tended to be large in size. Conclusions: SFTPs commonly arise from the visceral pleura and in accordance with tumor progression they will form a non-bloodstream connection with the parietal pleura. Finally, a vascular pedicle will arise with the parietal pleura.