Contact Dermatitis — Allergic and Irritant

A 38-year-old female beautician presents with a 3-week history of pruritic erythematous patches on her dorsal hands and forearms. The lesions are sharply demarcated, with vesicles and crusting. She reports the rash began after she switched to a new brand of hair dye containing para-phenylenediamine (PPD). Patch testing with PPD is positive. On examination, the rash is confined to areas of direct contact with the dye. What is the most likely diagnosis?

A 52-year-old male factory worker presents with a 2-day history of painful erythema and blistering on his hands and forearms. He reports exposure to a strong alkaline cleaning agent (sodium hydroxide) during his shift. The lesions are ill-defined, with maceration and erosions. Patch testing is negative. He has no prior history of skin disease. What is the most likely diagnosis?

A 52-year-old male factory worker presents with a chronic, non-vesicular, erythematous, and lichenified rash on his hands and wrists that has persisted for 6 months despite topical corticosteroids. He reports that the rash worsens with repeated exposure to cleaning agents and improves on weekends and holidays. Patch testing with common allergens is negative. Which of the following is the most likely diagnosis?

A 38-year-old female hairdresser presents with erythematous, vesicular lesions on her hands and forearms that began 3 days after using a new hair dye product. She reports intense pruritus and burning sensation. On examination, the rash is sharply demarcated, with edema and vesicles confined to areas of direct contact with the dye. Patch testing with the dye components is planned. Which of the following best explains the pathophysiology of her condition?