Disorders characterized by increased vascular fragility

• These diseases are also called nonthrombocytopenic purpuras because they aren’t associated with platelet abnormalities; they make petechial and purpuric hemorrhages on the skin and mucus membranes without a lot of bleeding

• Platelet count, bleeding time, and other coagulation tests are usually normal unless DIC complicates the issue

• Microbiological damage to the vessels (vasculitis)

  • From bacteria: menigococcemia, sepsis from other bacteria, typhoid F, scarlet F, leptospirosis, diphtheria, TB

  • Viruses like measles and small pox

  • Rickettsial diseases like RMSF and typhus

  • Protozoal diseases like malaria and toxoplasmosis

• Drug reactions

  • Often from Abs made to drugs and vascular deposition of immune complexes with production of hypersensitivity (leukocytoclastic = necrotic neutrophils around the blood vessels) vasculitis

  • Examples

    • Atropine

    • Quinine

    • Phenacetin

    • Aspirin

    • Coumarin

• D/o of collagen production lead to decreased vessel support

  • Inherited

    • Ehlers-Danlos syndrome

    • Osteogenesis imperfecta

    • Pseudoxanthoma elasticum

  • Acquired

    • Scurvy

    • Corticosteroid purpura (protein wasting)

    • Cushing’s syndrome (protein wasting)

    • Senile purpura (atrophy of collagen)

• Henoch-Schonlein purpura

  • Systemic hypersensitivity reaction of unknown cause with vascular deposition of immune complexes

  • The purpuric rash is seen with colicky pain, polyarthralgia, and acute GN

  • A barium enema will show a “thumbprint” sign from filling defects of the colon due to bleeding into and edema of the bowel (impinges on lumen)

• Hereditary hemorrhagic telangiectasis

  • AD d/o

  • Associated with dilated, tortuous, thin walled blood vessels

• Amyloidosis

  • Primary or secondary lymphoproliferative syndrome

  • Amyloid infiltration of blood vessel walls weaken them and cause mucocutaneous petechiae

Category: Medical Subject Notes , Pathology Notes