Dermatitis

COMMON SKIN TERMS
  • Lichenification: areas of thickened skin divided by deep linear furrows Medscape 

  • ECZEMATOUS DERMATOSES
    • Wide group of disorders that share the common
      • clinical features of Itching, Red, Scaly, vesicular to crusted rash (MKSAP 16) 
      • histological feature of spongiosis (intracellular edema of the skin resulting in spongy consistency (MKSAP 16)

    • Atopic Dermatitis: Dermatitis, Atopic (VisualDx)
      • Often termed as "eczema" but perhaps the use of the term is best avoided given the above explanation (MKSAP 16)
      • Hallmark of Atopic Dermatitis is Intense Itching (Visual Dx) 
      • Diagnosis: Challenging as no single distinctive features / lab
        • Is based on combination of patient and family history and clinical findings
        • personal or family history of atopy, allergic rhinitis or asthma, and pruritus
      • Reference:
 

    • Stasis Dermatitis: 
      • Management:
        • Goal: Reduce venous hypertension. Leg compression using knee-high support stockings (20-40 mm Hg of pressure) is recommended whenever possible but should be avoided in those with significant peripheral arterial disease (MKSAP 16) 

    • Nummular Dermatitis: Nummular dermatitis (VisualDx)

    • Contact Dermatitis
      • Allergic Contact Dermatitis: Allergic contact dermatitis (VisualDx)
        • More acute and more inflammatory than irritant dermatitis 
        • Type IV, delayed type hypersensitivity reaction mediated by allergen specific T-Cell mediated Dermatitis 
        • Edema and vesicles may be present in acute phase 
        • Lichenification and fissuring are common in chronic phase 
        • Diagnosis: Epicutaneous Patch Testing (MKSAP 16)
          • Note: 
            • Patch testing is different from prick or scratch testing. 
            • Prick or Scratch testing and radioallergosorbent tests (RASTs) assess for type I or IgE-mediated allergies and therefore have no role in the evaluation of allergic contact dermatitis. (MKSAP 16)
        • Reference: 
          • Medscape
  

      • Irritant Contact Dermatitis: Irritant contact dermatitis (VisualDx) 
        • Vesicles are rare unlike in Allergic CD
        • Pathogenesis: Non-immunogenic - Direct Toxic Injury to skin  
        • Examples
          • Chronic hand Dermatitis from frequent hand washing
          • Dermatitis from lip licking 

  • HAND DERMATITIS  Hand dermatitis (VisualDx)
    • Acute Presentation: Pruritus, Vesicles (can weep and crust), Erythema
    • Chronic Presentation: Scales, Lichenification, Fissuring, Skin Thickening
    • Pathophysiology: Disruption of epithelial barrier (Superficial Stratum Corneum, Deficiencies of protective Lipid Layer)
    • Etiology (Top 3 etiology account for 70% of Hand Dermatitis) :
      • Atopic Hand Dermatitis 
      • Allergic Contact Hand Dermatitis : Type IV Delayed Hypersensitivity
      • Irritant Contact Hand Dermatitis
      • Hyperkeratotic / Psoriasiform Dermatitis
      • Nummular Dermatitis
      • Pompholyx / Dyshidrotic Eczema / Vesicular Hand Dermatitis
    • DDx: Tinea Manum, HFMD, Secondary Syphilis, Scabies, Psoriasis

  

  • Phototoxic Drug Eruption 
Phototoxic Dermatitis NEJM 2014

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