 Good evening everyone. I am Dr. Pooja, JR2 from Naira Medical College and Hospital, Sassaram. Today I am going to present a case on chondromixoid fibromas. Introduction. Chondromixoid fibromas are extremely rare, benign, cartilaginous neoplasm that account for less than 1% of all bone tumors, most commonly diagnosed before 30 years of age, mostly during second and third decades. There is no sex predilection in case of CMF. Now coming to my case, an eight-year-old male came with the complaint of pain and swelling in later aspect of distal one-third of right leg which was present for five months and was progressive in nature. Exid was performed and these are the radiological findings, multi-loculated eucent lesion which was eccentrically located in the meta-diaphysis of distal left tibia having narrow zone of transition and thin slerotic rim was noted. This was the lesion having narrow zone of transition and thin slerotic rim was noted. Next CT was performed. Here we can see moderately sized lesion of size approximately 3 into 1.5 centimeter which is multi-loculated radiolucent lesion is eccentrically located in the meta-diaphysis of the distal left tibia having narrow zone of transition and thin slerotic rim likely benign neoplasm. Next MRI was performed and a cortical based lesion of size 3 into 1.5 into 4 centimeter was noted with erosion of lateral cortex involving the distal tibial metaphysis and diaphysis not involving the growth plate which appeared hypo intense on T1. The lesion appeared hyper intense on T2 with her hypo intense rim this was the hypo intense rim which correspond to slerotic border and this represent the benign nature of the lesion. There is no surrounding edema hemorrhage necrosis or fluid level noted within the lesion and no significant extra oscis soft tissue involvement was seen. Next the lesion appeared hyper intense on T2 and ster. Post-contrast study showed heterogeneous enhancement in the lesion. Now coming to differential diagnosis the diagnosis was made benign neoplastic lesion of the bone and most likely differential diagnosis diagnosis made was chondromixoid fibroma and non ossifying fibroma. Then USG guided FNAC was performed on the patient and the smear confirmed it as chondromixoid fibroma this is the FNAC report of the patient. Coming to discussion most chondromixoid fibromas are located in the metafysal region of the long bones approximately in 60% of cases and may extend to the epifysal line. The classical site is the upper one-third of the tibia which accounts for 25% of all cases with the small tubular bone of the foot the distal femur and the pelvis or sacrum being other relatively common locations. These are the typical sites and these are less typical sites. Radiological features of chondromixoid fibroma mostly tibia is involved in 50% of cases and the lesion is metafysal it is a geographical reason which is eccentric oval or rod it causes endosteal scalloping it is expensile have soap bubble appearance and rarely calcification can be seen in matrix in few cases. Now coming to MR findings on T1 weighted image it is iso intense to skeletal muscle and internal hyper intense pokai can be seen in 37% of cases on T2 weighted imaging two patterns can be seen first may have peripheral band of intermediate signal with central hyper intensity second diffusely and homogeneously hyper intense on T1 weighted contrast there is peripheral nodular enhancement which correspond to peripheral band of intermediate signal on T2 MR another contrast enhancement can be seen in the form of diffuse enhancement. Now coming to DD of chondromixoid fibroma it includes aneurysmal bone cyst giant cell tumor. Giant cell tumor is well defined and have non-cellerotic margin in most cases non ossifying fibroma and chondroblastoma which occurs in younger age group and metaphyseal fibrous defect. This is the case of aneurysmal bone cyst in a patient which is sharply defined leucine bone lesion with thin wall cavities and on MR we can see fluid fluid level which is characteristic of aneurysmal bone cyst. Next DD is giant cell tumor this is the APN lateral x-ray of the knee which demonstrate leucine lesion located eccentrically within the distal lateral femur abelting the articulate surface and later it was confirmed as giant cell tumor pathologically also on MR a well-defined lesion in the distal metaphysis and was seen which extent which was which extend to the epiphysis of the right femur and was hypo intense on T1 and hyper intense on T2 and ster and was and show enhancement on post-contrast study there was small cystic lesion small cystic lesion within the lesion which was also demonstrated on T2 weighted images. Next DD is non ossifying fibroma this is the ankle x-ray which demonstrate a well circumscribed eccentrically sense in the diaphysis or metaphysis of the tibia the margins are slightly slerotic there was no periosteal reaction and it doesn't about the growth plate it was a case of NUF. MRI demonstrate an eccentric well-defined lesion composed of soft tissue which was a hypo intense on T1 and T2 both but shows a post-contrast enhancement it was a case of non ossifying fibroma. Now coming to summary condom x-ray fibroma is one among the many benign lytic lesions of the bone potential sites are proximal tibia and foot although the name suggests that it is a conduit lesion but calcification are usually not seen it resembles non ossifying fibroma. Now summarizing all thing well-defined osteolytic bone tumors and tumor like lesions have a plethora of differentials in different age groups. For simplicity a wide widely used mnemonic for lytic bone lesion is fog machines which include fibrous dysplasia, fibrocortical defect, osteoblastoma, giant cell tumour or geodes, metastasis myeloma and urizomal bone cysts, condom x-ray fibroma, condoblastoma, bronze tumor in case of hyperparathyroidism, osteomyelitis, infarction, non ossifying fibroma in condoma, eosinophilic granuloma and simple bone cyst. Now we can differentiate these lesions on the basis of location and age. In less than 30 years in less than 30 years of patient we can consider the lesion as condoblastoma or infection if it is located in epifysal region. If it is located in metafysal region we can consider condom x-ray fibroma in condoma, abc, simple bone cyst, non ossifying fibroma and if it is located in diaphysis we can consider fibrous dysplasia eosinophilic granuloma and if the patient is above 30 years of age and the lesion is in epifysal region then we can consider giant cell tumor, infexin and geode and if it is in the metaphysis we can consider in condoma, condosarcoma and if the lesion is in diaphysis we can consider it as metastasis myeloma or lymphoma. Thank you.