Observational medicine has solved the etiology of a familial seborrheic dermatitis, an allergy to hapten nicotine and allergen tobacco. Also a targeted treatment with sodium cromoglycate and then with Dead Sea salts shows well the involvement of tissue mast cells at the base of the sebaceous glands. Recently, epidemiological studies show a link of severity of seborrheic dermatitis in tobacco smokers. Also, it can be concluded that observational medicine is much faster to solve a skin disease in comparison with epidemiology.
Bernard J.L .Sudan, The power of observational medicine over the epidemiology of seborrheic dermatitis