Medical study of the skin and disease

One word substitute is Dermatology.

Dermatology: the branch of medicine concerned with the diagnosis and treatment of skin disorders.
Orthopaedics: the branch of medicine dealing with the correction of deformities of bones or muscles.
Venereology: the branch of medicine concerned with venereal diseases.
Homeopathy: a system of complementary medicine in which ailments are treated by minute doses of natural substances that in larger amounts would produce symptoms of the ailment.