True about Thrombocytopenic purpura is-
Thrombotic thrombocytopenic purpura (TTP)

TTP is included among a group of diseases called thrombotic microangiopathic which are characterised by widespread thrombosis in microcirculation.
The other disorder which is included in this group includes hemolytic uremic syndrome (HUS).
Small vessels like terminal arterioles and capillaries are involved. 

Pathogenesis of TTP

Patients with TTP are deficient in an enzyme called ADAMTS13 also known as vWF metalloprotease that degrades very high molecular weight multimers of vWF.
In the absence of this enzyme, these multimers of vWF accumulate in plasma and promote platelet macroaggregate formation throughout the microcirculation leading to symptoms of TTP.

Clinical features

TTP is characterized by a pentad of : -


Microangiopathic hemolytic anemia  → Because red cells are forced to squeeze through abnormally narrowed small vessels because of thrombi.
Thrombocytopenia  →  Due to consumption of platelets in the formation of platelet thrombi.
Neurological symptoms  →   Due to the presence of thrombi in CNS microcirculation.
Renal dysfunction   →  Due to the presence of thrombi in renal microcirculation.
Fever
Haemolysis is extravascular
Normal renal function test
Thrombosis in cerebral blood vessels
Immediate cure following plasmapheresis