Treatment of pediatric idiopathic pulmonary hemosiderosis with low-dose cyclophosphamide.

Objective: To report the safety and efficacy of long-term, low-dose cyclophosphamide therapy in a child with idiopathic pulmonary hemosiderosis (IPH).

Case Summary: A 7-year-old boy diagnosed with IPH 4 years previously was initially prescribed prednisolone. Because he only had a transient response to prednisolone, oral cyclophosphamide 2 mg/kg/d was later added. A dramatic improvement was noted during the subsequent follow-up. One year after cyclophosphamide therapy, the patient suddenly developed thrombocytopenia (platelet count 75 x 10(3)/mm(3)), with the platelet count decreasing to 10 x 10(3)/mm(3) over the following 10 months. Cyclophosphamide was tapered to an alternating daily dosage of 1 mg/kg. The tapering resulted in a subsequent increase in the platelet count, which was maintained between 20 and 50 x 10(3)/mm(3) without occurrence of petechiae or spontaneous bleeding. Under this reduced dosing regimen, the disease has remained in remission for >1 year.

Discussion: Due to the low prevalence of IPH, only limited data document the safety and efficacy of immunosuppressive therapy in treating this disease. Although our patient showed a good response to low-dose cyclophosphamide, he developed thrombocytopenia with its use. The mechanism is unclear, but it may be similar to that of high-dose cyclophosphamide-induced myelosuppression. Due to the development of thrombocytopenia, the use of cyclophosphamide was maintained under a reduced dosing regimen. The benefit of long-term immunosuppressive therapy is controversial, and more clinical evidence is required to support its continued usage.

Conclusions: Long-term, low-dose cyclophosphamide is effective in treating childhood IPH, but caution should be exercised due to the possible development of thrombocytopenia. Periodic monitoring of the platelet count in long-term treatment is recommended.