days in a 28-day cycle. It has been approved by the Food and Drug Administration for the treatment of refractory anaplastic astrocytoma and newly diagnosed glioblastoma multiforme. Clinical efficacy of temozolomide has also been demonstrated in melanoma, and a variety of other solid tumors [1] . Used as a single agent, temozolomide has also been shown to have activity against brain metastases from melanoma [2] . Three phase II trials have been reported using temozolomide in patients with brain

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... etastases from solid tumors [3] [4] [5] . We are reporting this case in order to direct the attention of researchers to another possible cause of pancytopenia in patients receiving chemotherapy. Case Report A 22-year-old female patient was admitted to our University Hospital with complaints of seizure and confusion. Neurological examination revealed disorientation of time and place, agitation, mild nuchal rigidity, and mild bilateral papilledema. Cranial magnetic resonance imaging revealed a 5 ! 6 ! 6 cm irregularly shaped mass with cystic components on the left temporal lobe that was causing peripheral edema and midline shifting. Dexamethasone (16 mg/day) and valproic acid as antiepileptic therapy were started. Total excision of the mass from the temporal lobe was performed. Histopathological examination of the specimens showed a high-grade malignant glioma. After surgery, maximum-dose radiotherapy was delivered to the left temporal lobe. Residual mass was detected upon follow-up cranial MRI Abstract Objective: To report pancytopenia caused by temozolomide, a second-generation alkylating agent. Clinical Presentation and Intervention: A 22-year-old patient presenting with seizures and confusion was seen in the emergency room. Cranial magnetic resonance imaging revealed a mass. After surgery, the patient was diagnosed with glioblastoma multiforme and was given temozolomide at 150 mg/m 2 on days 1 through 5 every 4 weeks. During the last cycle of temozolomide, grade 3 thrombocytopenia persisted. Possible causes of pancytopenia including vitamin B 12 deficiency were investigated. Conclusion: This case report shows that vitamin B 12 deficiency can be a potential cause of pancytopenia and it should be kept in mind for patients receiving chemotherapy.