Two cases of bone erosion produced by subcutaneous rheumatoid nodules about the elbow are reported. The usual pattern of articular and para-articular bone resorption is contrasted with the rare manifestation of bone-scalloping by rheumatoid nodules. Rheumatoid nodules must be included in the differential diagnosis of cortical bone erosions.Bone erosion underlying rheumatoid nodules has received little comment in the literature because of its rarity.132 The purpose of this brief report is to document two instances of this unusual manifestation of rheumatoid arthritis.
CASE 1R.P., a 46-year-old man with a 4-year history of rheumatoid disease involving the elbows, wrists, fingers, and knees, developed large subcutaneous nodules over the right forearm and elbow. There were 5 distinct masses, the largest measuring just over 2 in. in diameter (Fig la). There was marked inflammation of the synovial structures of both hands, with multiple tendon ruptures and dislocation of the wrists bilaterally. Firm, nontender movable nodules of smaller size were present in the left elbow region, dorsum of the small joints of fingers, pretibial regions, and over multiple vertebral spinous processes.Roentgenograms of the right elbow and forearm (Fig Ib) showed soft tissue masses overlying sharply outlined cortical bone erosions in the ulna and radius. These corresponded to the externally visible and palpable subcutaneous nodules. No periosteal reaction was present at the sites of erosion, suggesting that the nodules were not subperiosteal. Extensive surgical reconstruction of the right wrist and hand was undertaken, with excision of subcutaneous nodules about the elbow and forearm. These were not fixed to the periosteum and had the typical histological appearance of rheumatoid granulomas (Fig 2) .
CASE 2G.K., a 63-year-old man, noted the onset of rheumatoid arthritis 10 years ago, with pain and swelling in the right wrist. Subsequently, he developed similar involvement of the left hand and wrist and both elbows. In the past 3 to 4 years, large nodules appeared about the elbow. These were most prominent on the extensor surfaces of both forearms in the region of the ulna. Nodules were also present over the dorsal aspects of the interphalangeal joints of fingers. Roentgenograms of the left elbow showed two punched-out cortical defects in the proximal portion of the ulnar shaft, in precise relationship to the overlying rheumatoid nod-