Reddit reviews Glimpses of the Devil: A Psychiatrist's Personal Accounts of Possession,

Absurd to state there is no single documented case, there is plenty of documentation which describe this phenomenon.

Supernatural entities? Psychosis?

As an atheist, supernatural doesn't fit my world view, however, make of this what you will, it shows there is plenty of similar documented "cases"

• Spirit Possession and Exorcism: History, Psychology, and Neurobiology, Volume 1 - Mental States and the Phenomenon of Possession Patrick McNamara, PhD, Associate Professor of neurology at Boston University School of Medicine, Boston, MA. 2011.
  
  
• Glimpses of the Devil: A Psychiatrist's Personal Accounts of Possession
  
  
• The Growing Evidence for ‘‘Demonic Possession’’: What Should Psychiatry’s Response be? Journal of Religion and Health, Vol. 44, No. 1, Spring 2005, Stafford Betty.
  
  
• The Unquiet Dead: A Psychologist Treats Spirit Possession
  
  
• Possession Demoniacal & Other; T. K. Oesterreich, Professor, University of Tubingen, 1930
  
  
• Dissociative Symptoms and Reported Trauma Among Patients with Spirit Possession and Matched Healthy Controls in Uganda
  

http://www.amazon.com/Glimpses-Devil-Psychiatrists-Personal-Possession/dp/1439167265

The American psychiatrist M. Scott Peck came to believe in the reality of spiritual evil based not on personal religious experience but rather on the anomalous clinical presentation of two patients. He subsequently participated in a couple of exorcisms in the capacity of a psychiatrist and observer and wrote this book detailing the experience. It's "the first complete account of exorcism and possession by a modern psychiatrist" and makes for very interesting reading if you have the nerve.