A case of idiopathic thrombocytopenic purpura treated by splenic irradiation

A 74-year-old woman was in hospital because of a metastatic lung tumor from breast cancer. On April 3, 2001, the platelet count decreased to 4.1 × 10 ⁴/μl, on April 18, to 1.6 × 10 ⁴/μl. The number of megakaryocytes in bone marrow was rather small, but the concentration of platelet-associated IgG (PAIgG) increased and other diseases which were capable of inducing thrombocytopenia were excluded, and a diagnosis of idiopathic thrombocytopenic purpura was made. A 3-week course of corticosteroid therapy was ineffective. Splenic irradiation (1 Gy/fr, 3 fr/week, total 6 Gy) was performed instead of splenectomy because of her age, bad prognosis due to breast cancer stage IV and her general state was poor. Thereafter, although corticosteroid therapy was tapered, the platelet count increased to 7.8 × 10 ⁴/μl one month after the end of irradiation.