radiodermatitis (radiation dermatitis)

Etiology

• radiation exposure
• radiation therapy

Pathology

• acute
  • cytokine-mediated inflammation & DNA damage
  • damage of sebaceous glands & hair follicles in the dermal layer
  • destruction of regenerative basal cells
• chronic
  • permanent damage to the dermis
  • radiation destroys fibroblasts in the dermis, resulting in reabsorption of collagen & tissue atrophy
• radiation also stimulates growth of atypical fibroblasts which produce dense, fibrous tissue
• radiation also damages the vasculature of the dermal layer; blood vessels become prominent, dilated, & thin resulting in telangiectasias
• radiation may destroy the dermal melanocytes, leading to hypopigmentation, or it may trigger increased production of melanin, causing hyperpigmentation

Clinical manifestations

• acute skin changes (graded manifestations)
  • occur within 90 days of exposure
  • usually resolves within 3-4 weeks after cessation of radiation exposure
  • erythema & edema may begin within hours or days
  • epilation & dryness may occur within days to weeks
  • desquamation
    • dry desquamation
      • scaling, & pruritus
      • can occur after the 3rd week of radiation therapy or after a cumulative dose of 30 Gy
      • typically resolves within 1-2 weeks of therapy
    • moist desquamation
      • red, exposed dermis & serous oozing
      • occurs after 4-5 weeks of therapy or with 45 to 60 Gy
  • ulceration
  • necrosis
• late effects
  • can occur anywhere from 90 days to years after exposure
  • atrophy, fibrosis, telangiectasias, & pigmentation changes
  • progressive induration, edema, & thickening of the dermis

Differential diagnosis

• radiation recall dermatitis
• cellulitis
• eczema
• secondary skin malignancy
  • angiosarcoma

Management

• skin hygiene
  • bacterial decontamination (esp S aureus) reduces risk of acute radiation dermatitis
• emollients
• hydrocolloid dressing

More general terms

• dermatitis

More specific terms

• radiation recall dermatitis