The diagnosis of a primary psychiatric disorder requires the exclusion of an organic etiology. However, Brazilian public hospitals commonly lack resources. Diagnostic precision requires also the congruence of the clinical history and the natural history of the investigated disorder.

This study reports a rare case of hallucinations and retrograde amnesia, due to organic brain lesion but without other cognitive impairments.

Fifty-three-years-old male Brazilian, was evaluated after one year in Brazil after being missing for 25 years in USA. Encountering his family, he did not recognize his mother, did not remember his life in Brazil, including his infancy, nationality and mother language. He was found as a homeless in poor hygiene. In the exam, he only presented retrograde amnesia, without any disturbances of fixation memory, intelligence, formal thought, affect or psychomotor function. Patient reported hallucinations. Blood tests showed no abnormalities. EEG showed diffuse slow rhythms. Brain MRI showed cortical and hippocampal atrophy. After weekly evaluations for 5 months, he remained stable despite lack of prescription. Some weeks after MRI, patient reported frequent alcohol and inhalant use when missing. No hints of secondary gain were found until present.

Organic etiology was suspected due to atypical presentation: hallucinations, evocative amnesia, with no further cognitive and affect disturbances. This is not compatible with schizophrenia, dementia or dissociative disorder. The brain abnormalities and recent data highly suggest this etiological hypothesis.

Since this clinical presentation does not fit into any specific psychiatric category, the case will continue to be studied.

The authors have not supplied their declaration of competing interest.