This is Barry Bellosis, one of the musculoskeletal radiology fellows at Stanford University. 12 year old male presenting with three months of generalized right knee pain and limping. Concerned for osteosarcoma. The patient in this case presented with this pelvic radiograph demonstrating this ill-defined region of of lucency in the right medial femoral neck with some cortical disruption along its medial margin. There is also associated wide zone of transition. All these findings are suspicious for an aggressive lesion. In patients presenting with hip pain for which slipped capital femoral epiphysis is suspected, a pelvic radiograph can also be obtained. SCIFI or slipped capital femoral epiphysis would demonstrate widening of the physis or irregularity at its pre-sleep phase. On the acute sleep phase, the epiphysis is displaced posterior medially. This is not seen in this case. The patient then underwent MRI without contrast. Here on our coronal T1 imaging, we can see this mass as this is iso-intense to the surrounding muscle with surrounding soft tissue component right there. On our coronal T2, we can see this heterogeneously T2 hyper-intense mass or bright mass within the right femoral neck correlating to the findings on our T1. Additionally here on our axial T2 FATSAT and coronal T2 FATSAT, we can see this heterogeneously T2 hyper-intense or bright mass with some soft tissue component. All these findings are concerning for an aggressive osseous lesion such as osteosarcoma. On a different patient, on the 16-year-old female with shoulder pain, when we look at osseous lesion, we look at imaging findings that could suggest an aggressive or non-aggressive lesion. One of the things that we look at is the pattern of bone destruction. It could be geographic, mott-eaten, or permeated pattern. A permeated pattern is poorly visualized and suggests an aggressive lesion. Also, a mott-eaten pattern suggests an aggressive lesion. Other thing that we look at is the zone of transition between the normal and the abnormal bone. A non-aggressive lesion will have a narrow zone of transition, whereas an aggressive lesion will have a wide zone of transition where we can't really determine where here on the specific patient where the normal and the abnormal bone separates. The other thing that we look at is the presence or absence of periosteitis. For this specific patient, we can see this linear density arising from the cortex also seen here. This is a sign of periosteal reaction or specifically the sunburst type of periosteal reaction. More distally, we can see this elevated periosteum, which is also a sign of periosteal reaction known as the Codman's triangle. Both are a sign of an aggressive lesion and depicts the aggressive overgrowth of the lesion where the periosteum could not keep up. The other thing that we look at is a soft tissue involvement. In this specific case, we can see that there is some cortical destruction in the right humeral neck as seen here. There is an associated soft tissue component that we can see here. These are all signs of an aggressive lesion. The other thing that we look at is the location in the bone, whether it's epiphysis, metaphysis, diaphysis, or axial or appendicular skeleton, and also age of the patient. Some lesions or malignancies only occurs in children and some in adults. The associated symptoms, for example, night pain is associated with an aggressive type of lesion. The other things that we look at is the distribution of this lesion, whether it's monostatic or polyostatic. So this is the MRI within without contrast of this patient. Here in our proximal humerus, we can see a heterogeneous T2 hyper intense lesion with some soft tissue component also seen here on our coronal T1 imaging. There is bone marrow edema distally as seen here and some bone marrow signal abnormality on coronal T1. On our axial T1 FATSAT post contrast imaging, we can see that there is heterogeneous enhancement of this lesion and also of the surrounding soft tissue concerning for involvement.

2nd Edition, CASE 40

2nd Edition

Oncology

osteosarcoma

aggressive lesion

musculoskeletal evaluations

bone destruction

periosteal reactions