A 27-year-old male presented with swelling in the lower end of his tibia. A CT scan and FNAC revealed an eccentric expansilelytic lesion in the lower tibia with cortical breech and soft tissue extension consistent with a giant cell tumor. Biopsy of the lobulated mass with core necrosis and cystic changes confirmed the diagnosis of giant cell tumor. Giant cell tumors typically present as eccentric, expansile lesions in the metaphysis of long bones with relative sparing of the joint.

1. GCT – CASE REVIEW27 YR OLD MALE WITH SWELLING LOWER END OF TIBIA CT RT ANKLE : Eccentric expansilelytic lesion in lower end of tibia posteromedially with cortical breech and soft tissue extension ? mitotic lesion ( GCT / ABC). FNAC : Giant cell tumor of bone ( tibia lower end). MERCURY IMAGING INSTITUTE SCO 172-173 SEC 9C CHANDIGARHMERCURY IMAGING CENTRE SCO 16-17 SEC 20D CHANDIGARH

2. LOBULATED MASS WITH CORE NECROSIS , DEGENERATION SUBARTICULAR LOCATION

3. CYSTIC INTRASUBSTANCE CHANGE PSEUDOCAPSULE / OSSEOUS SCLEROSIS

4. EXPANSILE , ECCENTERIC SUBARTICULAR ,LOBULATED LESIONRELATIVE SPARING OF JOINT IS APPRECIATED

5. TIBILAIS POSTERIOR TENDON

6. TIBIALIS POSTERIOR TENDON

7. GCTOSTEOCLASTOMAOSTEOBLASTOCLASTOMAMYELOID SARCOMATUMOR OF MYELOPLAXUSFEATURES TO REMEMBEREccentericExpansilelytic lesion with narrow zone of transitionSubarticular ( mature skeleton)Metaphyseal ( immature skeleton)Open epiphyseal plate acts as barrier to tumor growth

8. LESSONS LEARNTHypointense border around the lesion is either osseous sclerosis / pseudocapsule.Core necrosis/ cysts/ degeneration – supports GCT as possibility ( Intratumoral ABC components) Tibia lower end is involved in 2 to 5 percent of cases.Soft tissue extension is more often than joint involvement.Joint involvement is rare in GCT ( appreciated more often in sacral joint).Narrow zone of transition appreciated between the lesion and normal region.