Radiologic resolution of malignant infantile osteopetrosis skeletal changes following hematopoietic stem cell transplantation

Abstract

Introduction: Hematopoietic stem cell transplantation (HSCT) is the only known curative treatment of malignant infantile osteopetrosis (MIOP). In this study, short-term serial bone surveys were used to assess radiologic evolution of skeletal changes after HSCT in MIOP.

Materials and methods: Baseline whole-body bone survey was performed in all patients. HSCT was successful in 14 patients (11 with full chimerism, three with mixed chimerism) in whom follow-up bone surveys were carried out at 6 and 12 months after HSCT.

Results: Normal corticomedullary differentiation was evident in five (P = 0.06) and 12 (P < 0.005) patients at 6 and 12 months, respectively. Abnormal endobone appearance in long bones, present in 11 participants at baseline exam, disappeared in eight (P = 0.008) and all (P = 0.001) patients at 6 and 12 months, respectively. In 6-month follow-up, rachitic changes significantly disappeared (P < 0.01) in long bones; however, they were evident in ribs of 12 patients (P = 0.50). No patient had rickets in ribs or long bones after 12 months.

Conclusion: We observed considerable resolution of MIOP skeletal changes after HSCT in all patients with either full or mixed chimerism. Rachitic changes in long bones, attenuated corticomedullary differentiation, and endobone appearance were the first to resolve. We propose using single long bone plain x-ray to demonstrate short-term skeletal response to HSCT.

Keywords: hematopoietic stem cell transplantation; malignant infantile osteopetrosis; radiologic resolution; skeletal changes.