[Unconventional hip arthroplasty for a 15-year-old benign bone fibrous histiocytoma in a pediatric patient]. / Artroplastía no convencional de cadera por histiocitoma fibroso benigno óseo en un paciente pediátrico con 15 años de evolución.

INTRODUCTION: Benign fibrous histiocytoma is a rare tumor with very stringent radiologic and histopathologic criteria. It accounts for approximately 1% of all the benign bone tumors. It may be located in both the soft tissues and bone. Its usual location is the shaft, the epiphyseal end of the long bones, the pelvis and the ribs. The age range of presentation is very broad, from 5 to 75 years; it occurs more frequently in young adults. It is rare in children. CASE: Female, 27 year-old patient who presented at 10 years of age with a tumor in the right proximal femur, which was diagnosed as benign fibrous histiocytoma. She underwent surgical en bloc resection and unconventional arthroplasty with a RIMAG prosthesis. She did fine, had no alterations of implant instability and bone quality. She is developing properly, with symmetry of the extremities and appropriate mobility. DISCUSSION: There are only a few articles addressing subtotal and total hip arthroplasty in pediatric ages. There are reports in adolescents ranging from infection to loosening, periprosthetic fracture, revision and, generally speaking, implant failure. However, we did not see this type of complications in this case, and the patient received appropriate management.