Presentation
Right knee pain.
Patient Data
Right distal femoral lateral condyle marrow infiltrative lesion eliciting low signal on T1, high signal on T2, and STIR WI. It shows lateral cortical erosion and associated extra-osseous soft tissue component invading the adjacent muscles. Associated enlarged popliteal lymph nodes are also noted. Moderate knee joint effusion.
Torn posterior horn of the medial meniscus. Torn anterior horn of the lateral meniscus. Sprain of the ACL.
FDG avid right distal femoral lateral condyle lytic lesion with SUV max 27. It shows lateral cortical disruption and extra-osseous soft tissue component.
FDG avid metastatic right popliteal and right external iliac lymph nodes.
Biopsy revealed large cell malignant lymphoma.
Case Discussion
Primary bone lymphoma (PBL) is a less common manifestation of lymphoma than secondary involvement from disseminated lymphoma.
Diffuse large B cell lymphoma (DLBCL) is the most common subtype. The bony pelvis and femur are the most common locations.
Differential diagnosis
For plain film presentation of permeative bone destruction consider 1: