A 28-year-old woman from Mumbai presents with severe pruritus, erythema, and oozing on her hands and forearms for 3 weeks. She works as a healthcare worker and frequently washes her hands. On examination, she has acute vesicles, erosions, and crusting with sharp demarcation at the wrists. Serum IgE is 280 IU/mL (normal <150). Patch testing is negative. She has a personal history of allergic rhinitis and a family history of asthma. What is the most likely diagnosis, and what is the primary pathogenic mechanism underlying her condition?