- Thrombocytopenic purpura (TP) is characterized by cutaneous hemorrhages occurring in association with a reduced platelet count.
- Hemorrhages are usually small (petechiae) but at times larger (ecchymoses).
- Occur at sites of minor trauma/pressure (platelet count < 40,000/μL) or spontaneously (platelet count < 10,000/μL).
Acute idiopathic thrombocytopenic purpura (ITP) mostly in children; drug-induced and autoimmune TP in adults.
Both sexes; HIV-associated TP—homosexual men > heterosexual females.
Etiology and Pathogenesis
Due to either decreased platelet production, splenic sequestration, or increased platelet destruction.
Decreased platelet production. Direct injury to bone marrow, drugs (cytosine arabinoside, daunorubicin, cyclophosphamide, busulfan, methotrexate, 6-mercaptopurine, vinca alkaloids, thiazide diuretics, ethanol, estrogens), replacement of bone marrow, aplastic anemia, vitamin deficiencies, Wiskott-Aldrich syndrome.
Splenic sequestration. Splenomegaly, hypothermia.
Increased platelet destruction. Immunologic: autoimmune TP, drug hypersensitivity (sulfonamides, quinine, quinidine, carbamazepine, digitoxin, methyldopa), after transfusion. Nonimmunologic: infection, prosthetic heart valves, disseminated intravascular coagulation, thrombotic thrombocytopenic purpura.
Platelet plugs by themselves effectively stop bleeding from capillaries and small blood vessels but are incapable of stopping hemorrhage from larger vessels. Platelet defects therefore produce problems with small-vessel hemostasis, small hemorrhages in the skin or in the CNS.
Usually sudden appearance of asymptomatic hemorrhagic skin and/or mucosal lesions.
Petechiae—small (pinpoint to pinhead), red, nonblanching macules that are not palpable and turn brown as they get older (Fig. 19-1); later acquiring a yellowish-green tinge. Ecchymoses—black-and-blue spots; larger area of hemorrhage. Vibices—linear hemorrhages (Fig. 19-1), due to trauma or pressure. Most common on legs and upper trunk, but may be anywhere.
Thrombocytopenic purpura Multiple petechiae on the upper arm of an HIV-infected 25-year-old male were the presenting manifestation of his disease. The linear arrangement of petechiae at the site of minor trauma are called vibices.
Petechiae—most often on palate (Fig. 19-2), gingival bleeding.
Thrombocytopenic purpura Can first manifest on the oral mucosa or conjunctiva. Here multiple petechial hemorrhages are seen on the palate.
Possible CNS hemorrhage, anemia.
Defines state of platelet production.
May be contraindicated due to postoperative hemorrhage; however, usually can be controlled by ...