Ans. d (Osteoclastoma). (Ref. Maheshwari Ortho 2nd/216 and Q. No.l of the same section of same paper)BENIGN BONE TUMORSOsteoclastoma or giant tumour OB GCT- They are commonly found in the epiphysis of a bone, lying close to the epiphyseal plate.- 'Soap-bubble' appearance is typical.- The cortex over the tumour may be destroyed and there may be periosteal elevation.- They can be treated by block excision but, unfortunately, they are commonly closely associated with a joint. - If they are rapidly growing or recur after excision they may be malignant and require more aggressive treatment.Osteochondroma- Most common benign bone tumor.- The commonest site is in the femur or the tibia around the knee.- They have bony pedicle which grows away from the epiphyseal plate and is covered in a large cartilage cap.- If they become painful or cap > 20 mm thick, possibility of malignant change considered.Osteoid osteoma- Most common true benign tumor of bone.- These benign tumours occur in children, adolescents and young adults.- They are commonest in the femur and tibia but can occur elsewhere, even in the spine.- Typically produce a constant aching pain, most noticeable at night and is sometimes relieved by aspirin.- CT most diagnostic and appears as sclerotic lesion with the characteristic radiolucent nidus.- Osteoid osteomas also show up very hot on radioisotope scans (double density sign).- Rx: RFA or Surgical excision. - common in the hands and the feet.- The condition of multiple enchondroma is called Oilier's disease. Multiple enchondroma with hemangioma is Maffuci's disease- Malignant change is not common but many chondromata when present this risk is increased. - have the same histological structure as fibrous cortical defects, but they are larger.- Most occur in children and adolescents between the ages of 10 and 20 years.- The x-ray appearance usually is characteristic with multilocular appearance or ridges in the bony wall, sclerotic scalloped borders, and erosion of the cortex.- Although most nonossifying fibromas regress spontaneously; If surgery is indicated, prefer curettage and allogenic bone grafting.ALSO REMEMBERRadiological evaluation of MSK disorders MethodImaging time, HCurrent indicationsA.Ultrasound<1Synovial cysts, Rotator cuff tears,Tendon injuryB.Radionuclide scintigraphy with 99mTcMDP1-4Metastatic bone survey, Evaluation of Paget's disease, Quantitative joint assessment, Acute and chronic osteomyelitisC.Radionuclide scintigraphy with111 In-WBC24Prosthetic infection, Acute osteomyelitisD.Radionuclide scintigraphy with 67Ga24-48Acute and chronic infection, Acute osteomyelitisE.Computed tomography (CT)<1Spinal stenosis, Spinal trauma, Osteoid osteoma, Tarsal coalition, SequestrumFMagnetic resonance imaging (MRI)1/2-2Sacroiliitis, Avascular necrosis, OsteomyelitisIntraarticular derangement and soft tissue. InjuryDerangements of axial skeleton and spinal cord,Herniated intervertebral discPigmented villonodular synovitisInflammatory and metabolic muscle pathology