Skin-nontumor / Clinical dermatology
Blistering disorders
Blood blister

Author: Erin M. Carlquist, M.D. (see Authors page)
Editors: Jerad Gardner, M.D., Lauren Stuart, M.D.

Revised: 8 June 2016, last major update July 2011

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Blood blister [title]

Definition / General
  • Blister formation following damage to subepidermal vessels without penetration of epidermis
  • Similar to friction blister, but with additional force causing damage to vessel walls allowing blood to enter blister cavity (Blister Prevention)
Terminology
  • Friction blister: blister caused by shearing force which subsequently fills with clear fluid
  • Blood blister: blister caused by excessive force which fills with blood
  • Hemorrhagic bullae: larger blisters (> 0.5 cm), often multiple and associated with underlying disease process
Sites
  • Exposed and friction-prone skin, most commonly hands and feet
Pathophysiology
  • A small pool of fluid, including lymph and blood, becomes trapped beneath skin following disruption of subcutaneous vasculature (Wikipedia)
Etiology
  • Due to damage to subepidermal tissue and blood vessels, without piercing the skin; fluid is lymph and blood
  • Usually due to mechanical trauma (often pinching) from tool, mechanism or weight without use of protective covering gear
  • Also may occur due to repetitive motions and friction in exposed or improperly protected skin surfaces
  • Extreme cold ("frost bite") has also been known to cause blood blisters
  • Sudden appearance of lesions on oral mucosa may be diagnostic of angina bullosa hemorrhagica (Minerva Stomatol 2010;59:139, eMedicine)
Diagrams / Tables

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Diagram

Clinical Features
  • Hemorrhagic blister usually occurring on exposed skin
  • Most commonly occurring on hands and feet
Diagnosis
  • Typically, a clinical diagnosis
  • If solitary, diagnosis is usually a simple blood blister
  • Multiple blood blisters of unknown origin may indicate an underlying process (see "differential diagnosis" below)
Treatment
  • Self-limited; no treatment is needed
  • Symptomatic treatment may include elevation of wound, application of cold pack or dressings
Clinical Images

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Blood blisters

Gross Description
  • Cutaneous vesicle or bulla filled with sanguinous fluid
Micro Description
  • Appear very similar to friction blisters, microscopically
  • Shearing forces disrupt the intercellular connections, usually within stratum granulosum layer of epithelium
  • Keratinocytes at base may show degenerative changes
  • Erythrocytes and a sparse inflammatory infiltrate may fill area of separation
Micro Images

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Compact orthokeratosis of volar skin

Differential Diagnosis