カルバマゼピンによる薬剤性免疫性血小板減少症の1例

抄録

Drug-induced immune thrombocytopenia （DITP） is diagnosed based on the clinical course due to the lack of a disease-specific diagnostic approach. However, general diagnostic criteria for DITP advocated by George et al. included two prospective items, which are impractical for clinicians when facing patients in the clinic. On the other hand, Arnold et al. proposed alternative diagnostic criteria which include no prospective items. In this report, we describe the clinical course of a case with DITP caused by carbamazepine （CBZ）, which was diagnosed using Arnold’s criteria and successfully managed. A 77-year-old woman presented to our clinic with the chief complaint of left tongue pain. She was diagnosed as idiopathic trigeminal neuralgia, and we prescribed CBZ. The pain disappeared, but she noticed petechial purpura on her extremities on day 10 of CBZ administration. Four days after that, it expanded to the breast and back. On day 15 of CBZ administration, blood tests revealed a marked decrease in platelet count of 1.1×10⁴/μl. At that time, she met Arnold’s criteria, and was diagnosed as DITP caused by CBZ. No evidence of intracranial hemorrhage was indicated, and the patient was instructed to rest in hospital. Also, we stopped the administration of CBZ. Consequently, the platelet count began to improve from day 3 of stopping CBZ to 20.4×10⁴/μl on day 6 and the petechial purpura disappeared on day 14. Since then, we have prescribed precavalin as a substitute for CBZ, and her clinical course has been uneventful.