Acute psychosis following initiation of ruxolitinib in post-polycythaemia vera myelofibrosis case report.

Polycythaemia vera (PV) is a myeloproliferative neoplasm (MPN) which can progress to myelofibrosis (MF), a phenomenon termed post-PV MF. Ruxolitinib is a Janus activated kinase (JAK) inhibitor that targets JAK1/2 mutations and is approved for treatment of high-risk MF. This is a case report of a patient with post-PV MF who developed acute psychotic disorder five months after commencing ruxolitinib and whose mental status returned to baseline within one week of stopping ruxolitinib. Importantly, there was no history of mental health disorder and no identifiable triggers for his presentation. Ruxolitinib has not previously been implicated in the development of psychosis but is known to cross the blood-brain barrier and affect multiple cell signalling pathways within the central nervous system. Together, this makes an association between ruxolitinib and neuropsychiatric symptoms plausible, yet further understanding of causal mechanisms is warranted.