Figure 10. Rheumatoid arthritis in a 61-year-old man. Coronal T2-weighted fat-suppressed image of the ankle shows a high-signal-intensity lesion with a surrounding hypointense rim (large arrow) in the inferior aspect of the talar body, features that represent an area of subcortical erosion with adjacent bone marrow edema. Several smaller areas of erosion in the calcaneus (small arrows) and high-signal-intensity synovitis in the tarsal sinus (*) support a diagnosis of erosive inflammatory arthritis rather than a neoplasm. Subchondral erosions and degenerative cysts, particularly larger (1–3-cm) lesions with adjacent edema and enhancement, were commonly misinterpreted as a neoplasm and resulted in needless referrals to the Orthopaedic Oncology Clinic. This case demonstrates the importance of recognizing an arthritic process.