When doctors cry wolf: a systematic review of the literature on clinical lycanthropy.

This paper provides an overview and critical reassessment of the cases of clinical lycanthropy reported in the medical literature from 1850 onwards. Out of 56 original case descriptions of metamorphosis into an animal, only 13 fulfilled the criteria of clinical lycanthropy proper. The remaining cases constituted variants of the overarching class of clinical zoanthropy. Forty-seven cases involved primary delusions, and nine secondary delusions on the basis of somatic and/or visual hallucinations which may well have affected the patients' sense of physical existence, also known as coenaesthesis. Cases of secondary delusions in particular warrant proper somatic and auxiliary investigations to rule out any underlying organic pathology, notably in somatosensory areas and those representing the body scheme.