Lycanthropy is the name given to "the mythical condition of lycanthropy, a supernatural affliction in which humans are said to physically shapeshift into wolves." The key word "mythical" indicates that lycanthropy does not exist in the sense of some human beings having the ability to turn into wolves under given conditions or at certain times.
There is an unusual psychiatric condition called clinical lycanthropy. Persons having this condition suffer from delusions that they have been or can be transformed into an animal - not specifically a wolf. The change may involve the person having the impression that s/he has, at some point in the past or present time, changed into some other type of animal. Various types of animals have been reported in case studies of persons having clinical lycanthropy.
This condition is considered a psychotic symptom, possibly related to a more common diagnosis of a "condition such as schizophrenia, bipolar disorder, or clinical depression."