Intraosseous ganglion cyst mimicking chondrosarcoma on MRI: a case report

BACKGROUND: The intraosseous ganglia is a benign cyst, rarely locate in the olecranon process. As intraosseous ganglia can mimic malignant bone tumor, computed tomography (CT) is important for diagnosis even when magnetic resonance imaging (MRI) suggests malignant bone tumor, such as chondrosarcoma. CASE PRESENTATION: In this paper, we report a 42-year-old woman with intraosseous ganglia in the olecranon process of the ulna. She complained pain in right elbow for 3 weeks. MRI revealed an intraosseous mass which initially diagnosed as chondrosarcoma. However, followed computed tomography (CT) demonstrated scattered intralesional gas and no underlying mineralization, and we can exclude chondrosarcoma from diagnosis. CONCLUSIONS: The intraosseous ganglia can mimic bone tumor in MRI; therefore, CT is essential for accurate characterization of bone tumor. Even if MR imaging strongly suggests chondrosarcoma of the bone, CT should be performed as additional study.