[Trichoma (Plica polonica) - a contemporary case with a historical disease].

We describe a 62-year-old patient with a chronic delusional disorder who presented with severely matted hair ("plica polonica"). Until the late 19th century such dreadlocks were considered as cause, consequence and treatment of mental disease. The historical development of "plica polonica" is briefly reviewed as an example of early and once popular psychiatric disease concepts.