Spontaneously relapsing and remitting primary CNS lymphoma in an immunocompetent 45-year-old man.

A 45-year-old immunocompetent man with primary central nervous system lymphoma (PCNSL) presented with multiple spontaneous relapses and remissions in the absence of steroid treatment. Because of the fluctuations with improvement in both the clinical course and MRI findings, alternative disorders were considered that led to delay of diagnosis and treatment prior to brain biopsy. This case and a handful of others with single remissions emphasize that PCNSL cannot be reliably ruled out by improving or disappearing symptoms, signs or traditional MR imaging abnormalities.