Purpura

For other uses, see Purpura (disambiguation).
Purpura
Petechiae and purpura on the lower limb due to infection-associated vasculitis
SpecialtyDermatology, hematology

Purpura (/ˈpɜːrpjʊərə/[1]) is a condition of red or purple discolored spots on the skin that do not blanch on applying pressure. The spots are caused by bleeding underneath the skin secondary to platelet disorders, vascular disorders, coagulation disorders, or other causes.[2] They measure 3–10 mm,[3] whereas petechiae measure less than 3 mm, and ecchymoses greater than 1 cm.[4]

Purpura is common with typhus and can be present with meningitis caused by meningococci or septicaemia. In particular, meningococcus (Neisseria meningitidis), a Gram-negative diplococcus organism, releases endotoxin when it lyses. Endotoxin activates the Hageman factor (clotting factor XII), which causes disseminated intravascular coagulation (DIC). The DIC is what appears as a rash on the affected individual.

  1. ^ "PURPURA English Definition and Meaning | Lexico.com". Archived from the original on October 17, 2019.
  2. ^ "UCSF Purpura Module" (PDF). Archived from the original (PDF) on 2013-10-02.
  3. ^ McKenzie, Shirlyn B. (2014). Clinical Laboratory Hematology. Williams, Joanne Lynne; Landis-Piwowar, Kristin (3rd ed.). Boston. p. 665. ISBN 978-0133076011. OCLC 878098857.{{cite book}}: CS1 maint: location missing publisher (link)
  4. ^ Robbins basic pathology. Kumar, Vinay; Abbas, Abul K.; Aster, Jon C.; Perkins, James A. (10th ed.). Philadelphia, Pennsylvania. 2017-03-28. p. 101. ISBN 978-0323353175. OCLC 960844656.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)