Table 1.

Few illustrated cases with clinical profile, radiological findings and follow up.

Case	Clinical	Imaging	Management
1.	8-year boy: gradually increasing, painful lower leg swelling. Examination showed tender, well defined swelling in infrapatellar region along the region of tibial condyle. advised.	AP and lateral X rays of the knee joint showed: •Ill defined lytic lesion with permeative bone destruction involving the proximal metadiaphysis of tibia along the tibial tubercle with a broad zone of transition and varying types of periosteal reaction. •Resorption of overlying cortex with displaced soft tissue planes. •No definite matrix mineralization seen.(Fig. 1A) Diagnosis: Aggressive lesion: Ewing’s Sarcoma MRI of the knee •T2 W and PD FAT SAT: hyperintense mixed intensity soft tissue lesion involving the proximal diametaphysis of tibia, and marrow infiltration is extending. upto the proximal one-third of the tibial shaft. There is extra-osseous extension of the mass lesion involving the muscles with extension till the subcutaneous plane and stretching of overlying skin. •Post contrast scans revealed heterogeneous enhancement of the mass lesion with early wash out of the contrast. •DWI images reveal diffusion restriction with ADC reversal confirming the malignant nature of the lesion (Fig. 1A). The lesion is involving the epiphysis, reaching unto the cortex and likely involving articular margin and cartilage with involvement of distal part of patellar tendon. PET CT revealed: •Strong FDG avidity in the lesion with no abnormal uptake in the rest of the tibia and proximal and distal joints or anywhere else in the body ruling out distant metastases. Lungs and liver were free of any metastasis (Fig. 1B).	Biopsy: Ewing’s sarcoma grade 3 (Fig. 1B). Treatment: Post chemotherapy surgery Wide resection and reconstruction by endo-prosthesis and knee joint replacement.
2.	15-year- boy: pain in left thigh region, gradually increasing in intensity. Examinations: vague swelling and diffuse tenderness in the proximal thigh region on left side.	AP and lateral X ray of the knee joint: •Permeative pattern of destruction in the proximal shaft of left femur involving metadiaphysis with a broad zone of transition. •Overlying cortex is ill defined with mixed sunray and onion peal type of periosteal reaction with presence of Codman’s triangle and effaced/displaced overlying fat planes. •No definite matrix mineralization (Fig. 2A). Diagnosis: Appearance represents aggressive bone tumor with Ewing’s sarcoma kept as principle diagnosis with other remote possibility of osteosarcoma. MRI of the left femur: •heterogeneously enhancing soft tissue mass lesion involving the proximal diametaphysis of femur with early enhancement in dynamic scans. •There is extra-osseous extension of the mass lesion involving mainly the vastus group of muscles and relative sparing of posterior compartment. •DWI images reveal diffusion restriction with ADC reversal confirming the highly cellular nature of the lesion (Fig. 2A). Radionuclide bone imaging: •Diffuse uptake in the lesion with no abnormal uptake in the rest body ruling out distant bony metastases or lung metastasis (Fig. 2A).	Biopsy: confirmed the diagnosis of Ewing’s sarcoma. Treatment: •adjuvant chemotherapy followed by wide resection and reconstruction by endoprosthesis including left hip prosthesis was done (Fig. 2B). •The margin of the removed part of the bone was free of disease and the patient is followed on adjuvant chemotherapy
3.	13-year- boy: pain in left mid thigh region with diffuse tenderness in the mid thigh region. Examination revealed diffuse tenderness in the mid thigh region. X ray of the left thigh was advised.	AP and lateral X rays of the femur: •cortical irregularity with aggressive periosteal reaction along the antero-medial aspect of mid shaft of left femur (Fig. 3A). Diagnosis: Possibility of aggressive bone lesion and MRI done for further evaluation. MRI of the left femur including the knee joint: •cortical thinning and irregularity along the antero-medial aspect of mid diaphysis of femur with diffuse and interrupted periosteal reaction and adjacent marrow edema. No obvious involvement of overlying thigh muscles (Fig. 3A) was seen. •DWI imaged reveals diffusion restriction with ADC reversal within the lesion. •Possibility of Ewing’s sarcoma was kept, radiologically. Chest X-ray was done which was within normal limits.	Biopsy: •Ewing’s Sarcoma. Treatment: •Euro Ewing’s protocol: extracorporeal Radiotherapy to the involved area (Fig. 3B). •The bone containing the tumor excised, and was subjected to single high dose of radiotherapy. •The treated bone replanted followed by adjuvant chemotherapy to the patient. •Post replant surgery X-rays were done (Fig. 3B) maintaining adjuvant chemotherapy.
4.	9-year male: history of pain and swelling in the right knee joint. Clinical examination showed a swelling in the lower end of the thigh with restricted movement at the knee. X ray of the right femur with knee joint was advised.	X ray of femur with knee: •an expansile mixed lytic and sclerotic lesion involving lower end of the right femur with broad zone of transition and resoprtion of the overlying cortex and aggressive periosteal reaction (Fig. 4A). There is extra-osseous extension of the lesion and new bone formation in the overlying soft tissue resulting in cumulus cloud formation. Diagnosis: Osteosarcoma of distal femur. MRI of the distal femur: •mixed intensity mass lesion involving the distal end of femur involving the meta-diaphysis, extension into the epiphysis, with intact articular margin of the femur and trans cortical and periosteal extension of the soft tissue. •Extra-osseous extension of the mass lesion is seen into the overlying soft tissue and posteriorly the lesion is extending into the knee joint (Fig. 4A). •MRI scans also revealed a focal T2 hyperintense lesion in proximal shaft of femur, skip lesion. Isotope scanning: •diffuse uptake in the lesion with no significant uptake in lesion in proximal femoral shaft.	Biopsy: •histopathology revealed predominantly osteoblastic cells with enhanced nucleocytoplasmic ratio and undifferentiation: high-grade osteosarcoma (Fig. 4B). Treatment: •Chemotherapy followed by surgical excision with negative surgical margins of the excised tumor. •Wide resection and reconstruction by endoprosthesis and knee joint replacement was done and follow up check radiograph (Fig. 4B).
5.	13 year girl presented with gradual increasing painless swelling over distal arm. She is a kabaddi player and got hit during a kabaddi match. Examination revealed a hard swelling along the anterior aspect of arm proximal to elbow joint. AP and lateral X-ray of arm are advised.	AP and lateral X rays of the forearm •diaphyseal lesion along external surface of lower humeral shaft with saucerization of the cortex, and new bone formation within the soft tissue and radiolucent mass extending into surrounding soft tissue. There is cortical thickening with Codman’s triangle seen at margin of the lesion (Fig. 5A). Diagnosis: Possibility of agsive lesion ; parosteal variety of osteosarcoma. Differential diagnosis: myositis ossificans in view of history of trauma. MRI: •heterogeneously enhancing soft tissue mass on surface of lower humerus showing dense areas of peripheral blooming representing new bone formation. No intramedullary invasion could be seen and erosion and saucerization of cortex. •DWI images reveal diffusion restriction with ADC reversal of the lesion (Fig. 5A). CT Scan: •confirmed cortical involvement with saucerization and dense mineralization in the soft tissue component. Periosteal reaction seen on the surface of bone. •CT guided biopsy was performed to establish a definitive diagnosis (Fig. 5A).	Histopathology: osteoblastic activity representing intermediate to high-grade osteosarcoma with extensive bone matrix and small amount of fibroblastic cellular atypia.
6.	A 25-year male swelling in the upper jaw region swelling started intraorally and gradually increased in size. It was associated with difficulty in opening of the mouth and pain on palpation. CT scan of the face and sinuses was advised.	CT scan: •thickening of the walls of maxillary sinus with osseous soft tissue mass and sunray type of ossification and periosteal reaction, obliterating the air space (Fig. 6A). •extension of the ossified soft tissue into the nasal cavity and floor of the mouth. Diagnosis: aggressive bone forming tumor: osteosarcoma. Chest X-Ray: revealed few calcified nodular lesions in both lungs (Fig. 6A). CT chest: confirmed the calcified nodules and also revealed a well-defined lytic lesion in D8 vertebra. MRI of the dorso-lumbar spine: •marrow infiltration of D8 vertebra and left sided posterior elements by enhancing soft tissue mass lesion with extra osseous extension of the soft tissue in adjacent muscles involving costovertebral junction (Fig. 6B). CT guided biopsy from this lesion (Fig. 6B) was done .	Histopathology (D8): high grade metastatic osteoblastic cells with proliferation of spindle cells, atypical chondrocytes and neo-osteogenesis, metastasis from high grade osteosarcoma. Treatment: •Neoadjuvant chemotherapy •Follow up scan revealed a mild regression in calcified nodular metastasis to the lungs and also there was regression in soft tissue associated with vertebral metastasis
7.	40 years male: pain and discomfort in left upper arm.	X-ray of the humerus: •a large expansile lytic lesion in proximal shaft of the left humerus with ill-defined margins and broad zone of transition. •Multiple internal septations were seen with thinning and irregularity of overlying cortex. •Few subtle foci of calcifications were seen within the lesion (Fig. 7). Diagnosis: Features were consistent with aggressive bone lesion with possibility of chondroid origin. MRI: •diffuse highly hyperintense signal mass lesion representing medullary calcific lobules and punctate low signal intensity foci representing medullary calcifications: chondroid matrix (Fig. 7).	Biopsy: •cartilaginous component with poorly differentiated and high cellular atypia confirming Chondrosarcoma. Treatment: Wide resection and reconstruction by endoprosthesis was performed followed by chemotherapy (Fig. 7).
8.	A 28-year-old female patient presented with increasing swelling and pain in right ring finger. Examination the swelling was localized to proximal aspect of the finger and movement at metacarpophalangeal joint	X-ray of the index finger: •large lytic lesion with few septations and thinning of the overlying cortex in proximal shaft of proximal phalanx of index finger extending up to the articular surface with well-defined margins. •narrow zone of transition. •No definite matrix mineralization orobvious cortical break could be delineated (Fig. 8A). Diagnosis: Findings were in favor of nonaggressive lesion with possibilities of GCT or enchondroma. MRI of the finger: •confirmed a large heterogeneous soft tissue lesion in the corresponding location with partial resorption of overlying cortex. •DWI images reveal restricted diffusion with reversal of signal on ADC (Fig. 8A).	Treatment: Surgery with bone graft was placed within the bone defect created postoperatively (Fig. 8B). Histopathology: multinucleated giant cells without evidence of malignant transformation: low grade Giant cell tumor.
9.	20 years old male patient presented with severe pain in right lower leg, and relieved by salicylates. Associated history of fever or malaise was absent.	AP and lateral X rays of the lower leg •focal cortical thickening along anterior and medial cortex of mid shaft of tibia (Fig. 9). Diagnosis: Possibility of Osteoid Osteoma MRI: •Axial T2-weighted MR images shows the nidus, with diffuse cortical thickening and there is edema in the surrounding bone marrow and soft tissue (Fig. 9). Nuclear scan: •Intense uptake at the site of lesion confirming the nidus (Fig. 9).	Treatment: Local excision of the cortex containing the tumor Histopathology: •to confirm complete removal of nidus. •Postoperative X-rays were obtained to confirm the complete removal (Fig. 9) and patient eventually was completely pain free.
10.	16 years female pain in right arm. No associated history of fever was elicited.	AP and lateral X rays of the arm: •a large eccentric expansile lytic lesion in proximal shaft of humerus involving metadiaphysis with well-defined margin and narrow zone of transitio and thinning of overlying cortex. •No matrix mineralization appreciated on plain X-ray. No obvious periosteal reaction or cortical break (Fig. 10). Diagnosis: features of benign bony lesion with possibility of simple bony cyst/fibrous dysplasia. MRI: •a well-defined fluid intensity lesion in proximal metadiaphysis of humerus. No evidence of heterogeneous signal or fluid - fluid level seen ruling out internal hemorrhage (Fig. 10).	Treatment: surgery with bony curettage and bone grafting.
11.	27 year female had a chest X-ray done for cough.	Chest X-Ray: Lungs were clear with clear costophrenic angles. However a dense expansile lesion seen in lateral aspect of left 6th rib (Fig. 11). CT scan An expansile lytic lesion in left 6th rib with thick sclerotic margins and central ground glass haziness consistent No associated soft tissue changes were seen (Fig. 11). Radiological diagnosis: Fibrous Dysplasia.
12.	26 years boy: palpable hard swelling below the knee joint.	X-ray of knee: •An osteochnodral outgrowth from the anterior aspect of proximal tibia. There is continuity of the lesion with the medullary cavity representing osteochondroma (Fig. 12). MRI •Confirm the thickness of cartilaginous cap and changes in adjacent soft tissue (Fig. 12).