Hydrocephalus and Hyponatremia as the Presenting Manifestations of Primary CNS Lymphoma

the cerebral convexity. He was then referred to our institution for further evaluation of presumed NPH. On admission, he was awake but apathetic and unmotivated. Vital signs were normal. He was confused and disoriented to time and place. He showed profound memory impairment and a MiniMental Status Examination read 5 out of 30. Cranial nerve, motor, sensory and refl ex functions were intact. Speech was slightly dysarthric and hypophonic. He was generally bradykinetic, accompanied by neither tremor nor rigidity. His gait disturbance was characterized by upright posture, widebased short steps, gait initiation diffi culty, shuffl ing, freezing and postural impairment. Routine blood works were normal except for mild hyponatremia (124 mmol/l). Serological tests for syphilis and AIDS were negative. Cerebrospinal fl uid (CSF) examination disclosed normal opening pressure, 3 white cells/mm 3 , normal glucose and elevated total protein (142 mg/dl). There were no malignant cells. Three consecutive therapeutic CSF drainages of approximately 70 ml failed to show any clinical improvement. Subsequent CSF tests for virus, tuberculosis, mycoplasma, syphilis, fungi and parasites were negative. One week after admission, he became drowsy and somnolent, with declining responsiveness. Marked hyponatremia (110 mmol/l) was noted and his Dear Sir, Although increasing incidence is reported, primary central nervous system lymphoma (PCNSL) is still uncommon in immunocompetent individuals. Accurate and timely diagnosis of PCNSL is often diffi cult because of its ambiguous clinical behaviors and inconsistent radiological fi ndings [1– 4] . We describe an unusual case of PCNSL whose clinical-radiological manifestations were fi rst suggestive of idiopathic normalpressure hydrocephalus (NPH) with hyponatremia.