The abnormal belief of having the skin infested by parasites is a syndrome with different etiologies. Approximately 12% of cases are induced by another patient with the same syndrome. In noninduced cases, two physiopathological brain mechanisms have been proposed: a delusion, or a primary abnormal tactile sensation with a secondary delusional elaboration. These two hypotheses have been characterized by Berrios as cognitive and sensorialist approaches, respectively. Although modern literature defines this syndrome as a delusion, early literature, particularly German, described both approaches, and even emphasized the sensorialist approach, classifying it as a chronic tactile hallucinosis. A thorough review of the literature suggests both mechanisms may be possible.