Giant cell tumor

There is a well-defined, oval-shaped, eccentric, lytic lesion noted in the medial aspect of epi-metaphysis of the distal third of femur. There is narrow zone of transition with no obvious periosteal reaction noted. There is no matrix mineralization. There is ill-defined, blurring of margin over its medial aspect. However, there is no obvious cortical destruction and no soft tissue component is noted. Visualized knee Joint space appears normal.

There is a well defined, oval shaped, eccentric, lytic lesion noted in the medial aspect of epi-metaphysis of the distal third of femur. There is narrow zone of transition with no obvious periosteal reaction noted. There is no matrix mineralization. There is cortical thinning with breach noted at the anterior, posterior and medial aspects of the lesion. The lesion appears 2.1mm away from the articular surface. Visualized knee Joint space appears normal.

Relatively well-defined, oval-shaped, eccentrically located, expansile, irregular marginated, T1 low/ T2 intermediate to slightly high/ PD FS high signal intensity lesion measuring ~ 5.6 x 4.6 x 3.3 cm noted on the epi-metaphysis of the medial aspect of lower end of femur. There is peripheral T1 low signal intensity rim. There are multiple, tiny, subcentimetric, T2/ PD FS high signal intensity areas noted within the lesion suggesting cystic areas. There is no fluid-fluid level.

On GRE, there is no blooming artefact. Post contrast study shows homogenous enhancement of the lesion. There is cortical thinning with breach noted at the medial, anterior and posterior aspects of the femur associated with enhancing, soft tissue component measuring ~ 1.9 x 0.5 cm protruding outwards from the margin of cortical breach just at the juxtacortical position at the medial aspect. Medially, there is loss of interface with vastas medialis muscle while posteriorly there is loss of interface with the medial head of gastrocnemius. The lesion is ~ 2.1 mm away from the articular surface of the femur.

Multiple, ill-defined, patchy, altered, PD FS high signal intensities which show enhancement on post contrast study are noted in the peri-lesional area in the distal third of femur suggesting bone marrow edema. There is minimal knee joint effusion.