“…While epithelioid and sarcomatous types can be seen in PMM, the incidence of biphasic tumors is lower than in pleural disease, and pure sarcomatous tumors are very rare. 51,52 As in pleural MM, the biphasic and sarcomatoid subgroups have a significantly poorer prognosis and are less amenable to treatment overall. 53,54 While definitions of pleural MM have proposed a minimum of 10% spindled growth for a biphasic designation, the less common occurrence of biphasic histologic appearance and the distinctly poorer prognosis of this group in PMM may make a minimum value less practical.…”