Contact Dermatitis

Clinical Presentation: Erythematous, scaly, and pruritic patches. In acute phases, vesicles or "weeping" may occur. The distribution is the most important clue—it is restricted to the area of contact with the offending agent.

Classic Clues by Type:

• Irritant (ICD): Non-immunological. Caused by direct damage to the skin (e.g., harsh soaps, detergents, "wet work"). Often presents as burning and dryness.
• Allergic (ACD): Type IV hypersensitivity. Requires prior sensitization (e.g., Nickel, fragrances, hair dye/PPD, latex). Often presents as intense itching and vesicles.

Atopic Eczema

• The Clue: Symmetrical involvement of flexural creases (elbows, knees) and a personal/family history of atopy (asthma, allergic rhinitis).
• Vs Contact: Contact dermatitis is asymmetrical and follows the pattern of an external exposure (e.g., only one wrist under a watch).

Tinea Corporis (Ringworm)

• The Clue: Annular (ring-shaped) lesion with central clearing and an active scaly border.
• Vs Contact: Contact dermatitis usually lacks the "ring" shape and central clearing. If unsure, a KOH mount will show hyphae in Tinea.

The Patch Test:

Gold standard for Allergic (ACD). Offending allergens are applied to the back under occlusion for 48 hours. A positive result shows erythema and papulovesicles.
*Note: Do not confuse with "Skin Prick Test" used for Type I allergies (asthma/hives).

Primary Management:

• Identification & Avoidance: The most critical step. Discontinue use of potential triggers (new jewelry, fragrances, detergents).
• Barrier Protection: Frequent use of emollients and gloves for "wet work."

Pharmacotherapy:

• Topical Steroids: Betamethasone BD or Mometasone OD for 1-2 weeks.
• Loratadine 10mg OD
• Cetirizine 10mg OD
• Piriton 4mg TDS
• Potassium Permanganate (KMnO₄) Soaks: Diluted 1:10,000 for "weeping" acute lesions to dry them out.
• Prednisolone(Extensive rash): 30mg–50mg OD for 3–5 days.
  [Child: 1-2mg/kg OD] (max: 60mg).

⚠️ Clinical Pearl: If the rash is on the face or eyelids, consider airborne allergens or transfer from hands (e.g., nail polish or hand creams transferred to eyelids).

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