Diagnostic Utility of Various Techniques in Bone Tumours.

Bone tumours are relatively uncommon. The precise incidence of specific bone tumours is not known, because many bone lesions are asymptomatic and are not biopsied. In 1958, Jaffe pointed out the importance of correlation between the surgeon, the radiologist and the pathologist in diagnosis of bone lesions 1. Tumours of the skeletal system are relatively constant in their presentation. The five basic parameters of importance in this regard are the age of the patient, bone involved, specific area with in the bone (epiphysis, metaphysis (or) diaphysis, cortex, medulla or periosteum), radiographic appearance and microscopic appearance. The pathologist should be fully aware of the first four before trying to evaluate the fifth. Symptoms are most often non specific in bone tumours. Most patients present with pain, swelling or both. Occasionally the patient present with pathological fractures. None of these features suggest a specific diagnosis. However there are some lesions of bone associated with specific symptomatology. A patient with an osteoid osteoma can presents with exquisite pain which is relieved with analgesic. A patient with Ewings sarcoma of bone may present with fever and increased ESR suggesting the diagnosis of osteomyelitis. This may lead to inappropriate therapy and delay in diagnosis. So symptoms are of limited value in arriving at a diagnosis. The age of the patient and the exact location of the tumours are extremely important. Most of the highly malignant sarcomas such as Ewings sarcoma and osteosarcoma occur in children. Lower grade sarcomas such as chondrosarcoma occur in adults. The location and extent of the lesion are of great importance. Giant cell tumour usually occur at the epiphyseal end of the bones. A lesion containing a large number of giant cells occurring in a location such as metaphysis (or) diaphysis should suggest the possibility of some other process – such as hyperparathyroidism, osteosarcoma (or) Aneurysmal bony cyst. About half of the osteosarcoma arise around the knee either in the distal femoral (or) proximal tibial metaphysis. A cartilaginous neoplasm involving the flat bone is a chondrosarcoma. Roentgenographic appearance is of great importance. The roentgenogram is the best way to localize the lesion. There are several radiological features that aid in diagnosing a benign from malignant lesion. Benign tumours tends to be well circumscribed and may have a sclerotic rim. Malignant tumours tend to be poorly circumscribed. Most spindle cell sarcomas tend to show geographic areas of destruction. Geographic destruction refers to a large hole in the bone. Small cell malignancies such as Ewings sarcoma tends to show permeative destructive process, this refers to a moth eaten appearance in which there are multiple small holes in the bone with intervening residual bone 1. The character of the periosteal reaction is important. Benign lesions such as Langerhan cell histiocytosis show thick, regular periosteal new bone formation. Malignant tumours such as Ewings sarcoma tends to form multiple layers of poorly organized new bone in the periosteum. Existing estimates suggest however, that benign tumours are more frequent in males. Data concerning bone sarcoma are more comprehensive and reveal that males and females are affected at a ratio of 1 : 0.7. Although primary tumours develop in all parts of the skeleton, most demonstrate a predilection for the long tubular bones. Benign tumours tend to arise in the appendicular skeleton, with approximately 45% developing in the femur and tibia, usually about the knee. In comparison to benign tumours, bone sarcomas more frequently involve the pelvis and axial skeleton and rarely affect the small bones of hands and feet