[A Case of Idiopathic Thrombocytopenic Purpura during Adjuvant Chemotherapy for Colon Cancer].

A 76-year-old man underwent surgery for sigmoid colon cancer. The pathological finding was stage Ⅱ with a high-risk of recurrence (SI [bladder], l y0, v2, pN0, H0, P0, M0). He was treated with TS-1 as adjuvant chemotherapy. After the 1 course of chemotherapy, his platelet count was 4,000/mL. The high index of platelet associated IgG (PA-IgG) and bone marrow examination suggested that thrombocytopenia was caused by idiopathic thrombocytopenic purpura. The platelet count improved by prednisolone administration and Helicobacter pylori eradication treatment. After 6 months with no administration of adjuvant chemotherapy, the colon cancer recurred locally, and we performed a Hartmann's operation.