Giant Cell Tumor of Patella with Secondary Aneurysmal Bone Cyst-A Rare Case Report of Anterior Knee Pain in Young Adults.

INTRODUCTION: Primary bone tumors of the patella are rare, with an incidence as low as 0.12%. The majority are benign, with giant cell tumors (GCT) being the predominant tumor affecting this sesamoid bone. An associated secondary aneurysmal bone cyst (ABC) component with a primary patellar GCT is rarely seen.

CASE REPORT: We report a case of a 20-year-old male with long-standing anterior knee pain for 9 months. Having visited multiple clinics and found no relief, the patient presented to us at our out-patient department. Clinical examination suggested patellar tenderness, and knee radiographs showed a lytic lesion with cortical erosions. Computed tomography and magnetic resonance imaging were suggestive of GCT. A patellectomy with a good extensor repair was performed. A patellar biopsy revealed a mixed picture of a primary GCT with a secondary ABC. The patient was closely followed up, and at 12 months, he recovered completely and recorded an excellent functional outcome.

CONCLUSION: With the incidence of bone tumors on the rise, one should be aware of this relatively rare cause of anterior knee pain. A simple radiograph will help in early diagnosis and will go a long way toward better salvage procedures than more radical procedures like patellectomy.