Name : Morteza
Family :Sanei Taheri
Affiliation : ----------------
Academic Degree: ----------------
Resident : Samira Shahhamzei
Gender : Male
Age : 35
A middle age man with knee pain
Imaging Procedures and Findings
Figure 1 and 2 show an osseous mass with continuity of the cortex and medullary cavity of the lesion with that of the femur suggestive of osteochondroma. The cartilage cap thickness was about 4 mm (not shown). inflamed and distended bursa is seen over the lesion. Bursa is differentiated from cartilage cap only in GRE images (see discussion). Plain graphy demonstrates osteochondroma with Undertubulation (a widened diameter of the bone) as well and the bone scan is hot .
Osteochondromas (exostoses) are the second most common benign tumor of bone after nonossifying fibromas. The most common locations are around the knee (distal femur and proximal tibia) and the proximal humerus. The morphology of an osteochondroma is more important than the signal intensity in terms of diagnosis. Both CTand MRI demonstrate the continuity of the cortex and medullary cavity of the osteochondroma with that of the parent bone .The perichondrium is well seen on T2-weighted MR images as an area of low signal intensity surrounding the outer surface of the high signal intensity cartilage cap. MRI measurements of cartilage cap thickness are also accurate. The thickness of this structure is important in distinguishing benign osteochondroma from exostotic chondrosarcoma. The cartilage cap is usually thicker than 1.5 cm in chondrosarcoma. The formation of a bursa over an osteochondroma is common, and the bursa is usually asymptomatic; if it becomes inflamed and distended, it can be painful. On T2-weighted images, bursal fluid has high signal intensity similar to that of the cartilage cap, and it can be difficult to differentiate the two. On gradient echo sequences, cartilage has a lower signal intensity than that of fluid, and the diagnosis is easily made.
Hagga John R. CT AND MRI OF THE WHOLE BODY . 5TH edition P2134