A farmer presents with itchy eczematous dermatitis predominantly on sun-exposed areas of the face, neck, and forearms, worsening each season when a particular weed flowers nearby. Airborne plant particles are suspected. The most likely causative weed is:
- A Calotropis gigantea
- B Parthenium hysterophorus ✓
- C Ricinus communis
- D Datura stramonium
Correct answer: B. Parthenium hysterophorus
Explanation
Parthenium hysterophorus (carrot grass, gajar ghas) is the leading cause of airborne contact dermatitis in India, affecting farmers and those living near flowering plants, with lesions on exposed sites aggravated by sunlight. Sesquiterpene lactones such as parthenin are the allergens. Calotropis causes milky-sap dermatitis from direct contact rather than airborne sensitisation.
Reference: IAL Textbook of Dermatology, 5th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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