Musculoskeletal MRI Unknown Cases Texas Radiologic Society 93rd Annual Scientific Meeting Austin, TX April 21-23, 2006

1. Musculoskeletal MRI Unknown CasesTexas Radiologic Society93rd Annual Scientific MeetingAustin, TXApril 21-23, 2006 Lezlie R Warren, MD CPT USAF Justin Q Ly, MD CPT USAF Douglas P Beall, MD Wilford Hall Medical Center San Antonio, TX Intro self and say what talk this is Say only 2nd yr resident Want to emphasize MRI, so those images first followed by other modalities I like nature // got distracted by internetIntro self and say what talk this is Say only 2nd yr resident Want to emphasize MRI, so those images first followed by other modalities I like nature // got distracted by internet

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3. 20 y/o male referred from outside hospital

4. Exophytic pedunculated lesion arising from dist femur w/ both cortical and medullary continuity Can see displacement of popliteal arteryExophytic pedunculated lesion arising from dist femur w/ both cortical and medullary continuity Can see displacement of popliteal artery

5. T2 FS Shows continuity of medullary portion of lesion and of cortex High signal cartilage cap w/ not well seen low signal lining (perichondrium) Just say �with this entity you will see���T2 FS Shows continuity of medullary portion of lesion and of cortex High signal cartilage cap w/ not well seen low signal lining (perichondrium) Just say �with this entity you will see���

6. Axial and sagittal CT shows medullary and cortical continuity Pedunculated, well marginated process affecting the distal femurAxial and sagittal CT shows medullary and cortical continuity Pedunculated, well marginated process affecting the distal femur

7. Angio shows compromise of the popliteal artery by this lesionAngio shows compromise of the popliteal artery by this lesion

8. Diagnosis?

9. Osteochondroma Most common benign bone lesion accounting for 20-50% of all bone tumors If multiple, associated with Multiple Hereditary Exostoses Results from the separation of a fragment of epiphyseal growth plate cartilage which subsequently herniates through the periosteal bone surrounding the growth plate Cases after surgery and traumaCases after surgery and trauma

10. Osteochondroma Complications: Deformity (cosmetic or osseous) Fracture (host bone or lesion) Vascular or neurologic compromise Bursae formation (bursa exostotica) Malignant Transformation to chondrosarcoma (1%) Also known as osteocartilaginous exostosis A developmental lesion, rather than a true neoplasm (results from the separation of a fragment of epiphyseal growth plate cartilage which subsequently herniates through the periosteal bone surrounding the growth plate There are cases of secondary osteochondroma, from sx or trauma, tansplantation of physeal tissue, or even after xrt Accounts for 15% of ALL bone tumors (B9 & malig) Malignant tx 3-5% in HME (from 1%) Fxr can be of host bone or of lesion Usuall dx�d before third decade w/ male predominance Osteochondroma has it�s own growth plate (therefore should stop growing at skeletal maturity) Likes metaphyses of long bones (knee and prox humerus) Usually directed away from neighboring growth plate Most important feature for dx is the uninterrupted merging of cortex with the host bone, and communication of medullary portion w/ parent bone The narrow band of low signal surrounding the cap represents the overlying perichondrium Can have calcs in stalk, B9 finding Can get inflammatory chgs of bursa covering cartilage cap NM not reliable for malig tx as both have incr uptake HME also known as multiple hered osteochondrom; familial osteochondromatosis, diaphyseal aclasis (AD); more frequently sessile type of lesion Calcs in cartilaginous cap, worrisome for malig tx Most common benign bone lesion accounting for 20-50% of all bone tumors The least common complication of an osteochondroma occurring in less than 1% of cases is malignant transformation to chondrosarcoma Clinical features suggestive of malignant transformation are pain (in the absence of fracture or bursitis), pressure on adjacent nerve, or growth of lesion beyond age of skeletal maturity Also known as osteocartilaginous exostosis A developmental lesion, rather than a true neoplasm (results from the separation of a fragment of epiphyseal growth plate cartilage which subsequently herniates through the periosteal bone surrounding the growth plate There are cases of secondary osteochondroma, from sx or trauma, tansplantation of physeal tissue, or even after xrt Accounts for 15% of ALL bone tumors (B9 & malig) Malignant tx 3-5% in HME (from 1%) Fxr can be of host bone or of lesion Usuall dx�d before third decade w/ male predominance Osteochondroma has it�s own growth plate (therefore should stop growing at skeletal maturity) Likes metaphyses of long bones (knee and prox humerus) Usually directed away from neighboring growth plate Most important feature for dx is the uninterrupted merging of cortex with the host bone, and communication of medullary portion w/ parent bone The narrow band of low signal surrounding the cap represents the overlying perichondrium Can have calcs in stalk, B9 finding Can get inflammatory chgs of bursa covering cartilage cap NM not reliable for malig tx as both have incr uptake HME also known as multiple hered osteochondrom; familial osteochondromatosis, diaphyseal aclasis (AD); more frequently sessile type of lesion Calcs in cartilaginous cap, worrisome for malig tx Most common benign bone lesion accounting for 20-50% of all bone tumors The least common complication of an osteochondroma occurring in less than 1% of cases is malignant transformation to chondrosarcoma Clinical features suggestive of malignant transformation are pain (in the absence of fracture or bursitis), pressure on adjacent nerve, or growth of lesion beyond age of skeletal maturity

11. Osteochondroma Features suggestive of malignant transformation: Pain (in the absence of fracture or bursitis) Growth of lesion beyond age of skeletal maturity (own growth plate) Thick cartilage cap > 1.5 cm (is normally 1-3 mm, rarely > 1 cm)

12. Osteochondroma Imaging Findings: Pedunculated with slender pedicle, usually directed away from adjacent growth plate Or sessile, with a broad base attached to the cortex *There is communication of the cortex and the medullary portion of the lesion and host bone Calcifications in the chondro-osseous portion of the stalk (sign of benignity) Cartilaginous cap (high signal on GRE and T2 images)

13. Osteochondroma DDx: Osteoma Periosteal chondroma Juxtacortical osteosarcoma Soft tissue osteosarcoma Juxtacortical myositis ossificans Treatment: Solitary osteochondromas can be monitored in the absence of clinical symptoms or complications If malignant transformation is suspected, the lesion is surgically resected Osteoma: Ivory like sclerotic mass attached to bone; assoc w/ cutaneous and subcutaneous masses and intestinal polyps (Gardner syndome) Periosteal chondroma Lack of medullary and cortical continuity Juxtacortical osteosarcoma Aggressive features: periosteal reaction, soft tissue mass Soft tissue osteosarcoma Aggressive features: periosteal reaction, soft tissue mass Juxtacortical myositis ossificans History of trauma; lack of continuity w/ cortex and medullary space Osteoma: Ivory like sclerotic mass attached to bone; assoc w/ cutaneous and subcutaneous masses and intestinal polyps (Gardner syndome) Periosteal chondroma Lack of medullary and cortical continuity Juxtacortical osteosarcoma Aggressive features: periosteal reaction, soft tissue mass Soft tissue osteosarcoma Aggressive features: periosteal reaction, soft tissue mass Juxtacortical myositis ossificans History of trauma; lack of continuity w/ cortex and medullary space