unusual presentation of acute lymphoblastic leukemia masquerading idiopathic intracranial hypertension

Idiopathic intracranial hypertension (iih) is defined as increased cerebrospinal fluid (csf) opening pressure and abnormal fundoscopy when other causes of increased intracranial pressure are ruled out. we present a patient with a primary diagnosis of iih who had undergone a lumboperitoneal shunt. later she was treated with shunt revision, anti-tuberculosis drugs, and intravenous immunoglobulin. acute lymphoblastic leukemia (all) was diagnosed after bone marrow biopsy. the initial response to chemotherapy was promising. careful history taking, avoidance of unnecessary repetition of diagnostic procedures, avoidance of a tunneled vision, and a strong clinical suspicion is important to see the hidden causes underlying a difficult case of pseudotumor cerebri. acute lymphoblastic leukemia and carcinomatous meningitis should be sought in iih patients with abnormal presentation and unusual response to the known treatments.