What are the peripheral smear findings in platelet disorders?

Updated: Nov 30, 2019
  • Author: Perumal Thiagarajan, MD; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Answer

Answer

Careful examination of the peripheral smear is essential in a patient with thrombocytopenia.

Spurious thrombocytopenia due to platelet clumping or platelets adhering to neutrophils (platelet satellitism) can be seen on a smear (see image below).

Spurious thrombocytopenia. Peripheral smear of a p Spurious thrombocytopenia. Peripheral smear of a patient reported to have platelet counts of 10,000-150,000/μL on various occasions. The smear shows clumping of the platelets and satellitism involving neutrophils and platelets.

Giant platelets are often seen in patients with ITP (see image below).

Examination of peripheral smears in immune thrombo Examination of peripheral smears in immune thrombocytopenia often shows giant platelets. These platelets reflect the increased megakaryocytic mass in the marrow.

Rare disorders, such as Bernard-Soulier syndrome, can be diagnosed based on the results from the peripheral smear (see image below). Careful examination of the smear is essential to exclude TTP and rare instances of acute leukemia presenting as thrombocytopenia.

Peripheral smear of a patient with Bernard-Soulier Peripheral smear of a patient with Bernard-Soulier syndrome showing giant platelets. These platelets are not counted as platelets in most particle counters.

In TTP, a striking degree of red blood cell fragmentation is seen in addition to thrombocytopenia (see image below).

Examination of the peripheral smear shows red bloo Examination of the peripheral smear shows red blood cell fragments, basophilic cells, in addition to thrombocytopenia in thrombotic thrombocytopenic purpura.

The minimum criteria for the diagnosis of TTP are thrombocytopenia and microangiopathic hemolytic anemia without an apparent etiology.

Examination of the smear shows thrombocytopenia and a microangiopathic picture (characteristic helmet cells/schistocytes and basophilic red blood cells) (see image below). In addition, the lactic dehydrogenase (LDH) level is high, with brisk reticulocytosis. Signs of intravascular coagulation are characteristically absent in patients with TTP.

Schistocytes (thrombotic thrombocytopenic purpura) Schistocytes (thrombotic thrombocytopenic purpura).

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