LAUSR

Introduction and importance Chondromyxoid fibroma is a rare benign cartilaginous neoplasm, a mixture of benign cartilage and fibrous and myxoid tissue. It usually affects young people, commonly in the second and third decades of life with male being predominant. Differential diagnosess in chondromyxoid fibroma, are giant cell tumor, bone cyst, enchondroma, osteoblastoma, and low-grade chondrosarcoma. Case presentation We present a case of an 18-years-old male, with chief complaint of pain on the right knee since 3 year ago with an increasing size reaching diameter of 55 cm within three years. The radiograph and MRI revealed lytic blastic expansile multiloculated lesion, with wide transitional zone, and periosteal reaction on the epymetadiaphyseal part of right proximal tibia. The surgical procedure was performed consist of wide excision, reconstruction by cement knee arthrodesis using Kuntscher-nail, dynamic compression plate, bone cement and gastrocnemius flap. Clinical discussion After 3 months of surgery follow-up, there was no sign of recurrence, the patient walked partially weight bearing with a crutch. In 1 years post operative follow up, the Muscukoskeletal Tumor Society Scoring (MSTS) was 80%. There was no sign of recurrence. Conclusion In cases with large tumor size, wide excision with bone and soft tissue reconstructive surgery is required as mechanical and biological reconstruction. The cement arthrodesis provides a faster duration of surgery, lower risk of infection, and good functional outcome.