Summary

Ruxolitinib is a novel inhibitor of the Janus kinase (JAK) pathway that has become available for the treatment of myelofibrosis. There are increasing reports of opportunistic infections associated with ruxolitinib therapy. We present a case of Pneumocystis jiroveci pneumonitis complicating ruxolitinib therapy. Clinicians should consider the use of pneumocystis prophylaxis when using ruxolitinib.