Lucent Lesions of the Patella

Differential considerations for lucent lesions of the patella include:

• Dorsal defect of patella: Normal variant
• Subchondral cyst: Can be seen with osteoarthritis or pyrophosphate arthropathy.
• Amyloid deposition: In patients with renal disease.
• Chondroblastoma: Most common benign neoplasm of the patella. Round or lobulated with a well-defined sclerotic rim.
• Giant cell tumor: Geographical pattern of bone destruction. Involve more than 3/4 of the patella and lead to cortical thinning and septations. Locally aggressive
• Pigmented villonodular synovitis:
• Unicameral bone cyst:
• Aneurysmal bone cyst:
• Metastasis:
• Malignant tumor: Hemangioendothelioma, lymphoma, and osteosarcoma.
• Gout: Rare. Soft tissue component may be seen on MRI. Has a predilection for the superolateral aspect of the patella.
• Osteomyelitis: Rare. More common in adolescents (peak vascularity of the patella) or immunocompromised patients. No periosteal reaction (since sesamoids don't have a periosteal layer).

References

Singh J, James SL, Kroon HM, Woertler K, Anderson SE, Jundt G, Davies AM. Tumour and tumour-like lesions of the patella--a multicentre experience. Eur Radiol. 2009 Mar;19(3):701-12.