Purpura
Pronunciation: PUR-pyoo-rah
Non-blanching discolouration of the skin caused by extravasation of red blood cells into the dermis or subcutaneous tissue.
Full Definition
Purpura describes haemorrhagic discolouration that does not disappear (blanche) under pressure, distinguishing it from erythema or telangiectasia. It is categorised by size: petechiae (< 2 mm), purpura (2–10 mm), and ecchymoses (> 10 mm). Editors working on dermatology content must maintain these size distinctions precisely when they appear in diagnostic criteria or case descriptions. Purpura can be palpable — indicating vasculitis — or non-palpable, which guides the differential diagnosis. The term is always lower case; named variants such as Henoch-Schönlein purpura or Schamberg disease use initial capitals for the eponymic elements only.
Usage
Usage note: Verify size descriptors: petechiae < 2 mm; purpura 2–10 mm; ecchymosis > 10 mm. Non-blanching is the defining characteristic — flag any conflation with blanching rash.
In Context
- "Multiple non-blanching purpuric macules were observed over the lower limbs, raising concern for vasculitis." — Emergency department assessment
- "The case report used 'purpura' and 'petechiae' interchangeably; the editor corrected the size-specific terminology." — Journal copy-editing session