A Rare Case of CNS Limited B-Cell Acute Lymphoblastic Leukemia Presenting as Acute Onset Psychosis

We report a case of a 52-year old male who presented with acute onset psychosis without any systemic symptoms or signs, with normal routine blood biochemistry, peripheral smear and radiological imaging of the brain. Diagnostic lumbar puncture and Flow cytometry of CSF revealed evidence of B-cell Acute Lymphoblastic Leukemia with 44.2% blast cells. Further workup with bone marrow examination was surprisingly normal. PET-CT did not reveal evidence of any malignancy in any organ system other than CNS. B-ALL presentation limited to CNS is rare, and with sole psychiatric manifestation without any focal neurological deficits, meningeal and or systemic signs is even rarer. This case will definitely widen the scope of differential diagnosis of a case of acute-onset psychiatric symptoms in middle to late age.