Thrombotic microangiopathy

Thrombotic microangiopathy
Classification and external resources
Micrograph of thrombotic microangiopathy with the characteristic onion-skin layering seen in older lesions. PAS stain.
ICD-10	M31.1
ICD-9	446.6

Thrombotic microangiopathy, abbreviated TMA, is a pathology that results in thrombosis in capillaries and arterioles, due to an endothelial injury. It may be seen in association with thrombocytopenia, anemia, purpura and renal failure.

The classic TMAs are hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. Other conditions with TMA include disseminated intravascular coagulation, scleroderma renal crisis, malignant hypertension, antiphospholipid antibody syndrome, and drug toxicities, e.g. calcineurin inhibitor toxicity.

Etiology

The etiology is dependent on the specific TMA.

Bacterial toxins are the primary cause of one category of thrombotic microangiopathy known as HUS or hemolytic uremic syndrome. The another major category is TTP or thrombotic thrombocytopenic purpura. It is caused by autoimmune or hereditary dysfunctions that activate the coagulation cascade or the complement system.

Some sources group TTP and HUS together, while other sources express skepticism about their common pathophysiology.

Presentation

The clinical presentation typically includes: fever, microangiopathic hemolytic anemia (see schistocytes in a blood smear), renal failure, thrombocytopenia, neurological manifestations.

Treatment

The treatment depends on the underlying condition.

See also

• Microangiopathy