Case: Thrombocytopenic thrombotic purpura (TTP), a life-threatening event consisting of disseminated vascular thrombosis, has never been described before as a possible side effect of the anticancer drug pemetrexed. A 70 years old patient affected by a poorly differentiated non small cell lung cancer, subjected to his first pemetrexed administration, developed an acute thrombocytopenic thrombotic purpura, fatal in a few hours.
Conclusions: Pemetrexed can cause TTP. Clinicians have to be alert for the rapid onset and aggressiveness of this possible side effect. It is difficult to recognise the first signs and symptoms.