Megaloblastic Anemia Due to Intrathecal Methotrexate

We diagnosed to the patient as primary medias-tinal CD20 positive diffuse large B-cell lymphomatwo years ago. The patient received R-CHOP che-motherapy. Complete remission was obtained fromchemotherapy. After 18 months, headache, nauseaand vomiting occurred. Cranial magnetic resonanceimaging showed mass lesions. Cranial radiotherapywas applied. Then intrathecal methotrexate (MTX)was administered at a dose of 12 mg via lumbarpuncture twice weekly for 6 weeks. Pancytopeniawas detected after ten days of the discontinuation ofintrathecal MTX. There were apparent megaloblasticchanges on the bone marrow aspiration and biopsy.The biochemical parameters were folic acid 6.22 ng/ml(N:4.2-19.99) and cobalamin 803 pg/ml (N:197-866).The patient was treated with oral folic acid 5 mg/day.Hematological parameters were hemoglobin 10.2 g/dl, platelet count 432 000/mm3, and leukocyte count5100/mm3 at the 14th day. In conclusion, the patientstreated with intrathecal MTX should be followed-upand folic acid prophylaxis may be considered.