summary Chondromyxoid Fibromas are rare, benign, chondrogenic lesions characterized by variable amounts of chondroid, fibromatoid, and myxoid elements that are most commonly found in the metaphysis of long bones. Patients typically present between the ages of 10 and 30 with regional pain and swelling. Diagnosis is made with biopsy showing hypercellular area with lobules of fibromyxoid tissue and myxoid stroma with stellate cells. Treatment is usually intralesional curettage and bone grafting (or PMMA). Epidemiology Demographics more common in males most common in second and third decades of life may affect patients up to 75 years old Anatomic location long bones (ie. tibia, distal femur) often affects metaphyseal (proximal tibia) regions pelvis feet or hands Etiology Pathophysiology may arise from physeal remnants Genetics mutations a genetic rearrangement may affect chromosome 6 (postion q13) Presentation History long standing pain (months to years) may be incidentally identified Symptoms pain and mild swelling Imaging Radiographs findings lytic, eccentric metaphyseal lesion login to view 5 more bullets MRI findings low signal on T1-weighted images high signal on T2-weighted images Bone scan findings increased signal uptake will be seen Studies Histology findings low-power login to view 6 more bullets high power login to view 2 more bullets Diagnostic criteria histopathologic examination is mandatory for confirmation of the diagnosis Differential Radiographic aneurysmal bone cyst (ABC) chondroblastoma non-ossifying fibroma Histologic chondroblastoma enchondroma chondrosarcoma Treatment Operative intralesional curretage and bone grafting (or PMMA) indications login to view 1 more bullet Complications Recurrence occurs in 25% of cases Prognosis Natural history recurrence in CMF is not uncommon may occur in 20-30% of cases Negative prognostic variables children tumor is more lobulated with abundant myxoid material Metastasis has not been reported