Giant cell tumor of the patella with a secondary aneurysmal bone cyst: A case report.

The substance of the patella is an uncommon location for tumor occurrence and development. The present study reports a case of giant cell tumor (GCT) of the patella, combined with an aneurysmal bone cyst (ABC). To the best of our knowledge, this is the second report of GCT with ABC published in English. GCT is the most common type of benign tumor. Secondary ABC is frequently associated with GCT, but this symbiotic tumor rarely occurs in the patella. A 27-year-old male patient was examined at the outpatient clinic, and clinicopathological characteristics of the tumor were observed. X-ray and computed tomography (CT) scans revealed a lytic lesion located in the center of the right patella. Curettage, followed by autogenic and allograft bone grafting, was performed. Histopathologically, the lesion was diagnosed as a GCT with secondary ABC. No recurrence or metastasis was identified during the 1-year follow-up period. The present study reports a case of GCT with secondary ABC, and discusses the rare location and histopathological type of this tumor, in order to improve diagnosis and treatment of patellar tumors in general.