97 1 necrosis, and foci of plasma cells and lymphocytes beneath hypertrophic synovial epithelium, is seen and is typical of the findings listed in the ARA criteria for diagnosis of rheumatoid arthritis. The synovial membrane surface is thrown into folds or villous projections which extend into the joint space. Fibrovascular proliferation extending from the synoviocartilaginous junction across the articular cartilage results in bony cartilaginous resorption. These eroded areas of articular cartilage and periarticular bone are visualized radiographically as “punched out” or erosive lesions and are found most often in chronic rheumatoid arthritis. This disease is very similar to, if not identical with human rheumatoid arthritis. I bring this to your attention because some of these dogs may be found in homes of human rheumatoid arthritis patients. 1. REFERENCE Newton CD, Allen HL: Rheumatoid arthritis in dogs. Am Vet Med Assoc 168:113-121, 1976 CHARLES D. NEWTON, D.V.M., M.S. University of Pennsylvania School of Veterinary Medicine 3800 Spruce Street Philadelphia, Pennsylvania 19104 Resorption of the Mandible in Vinyl Chloride Acro-osteol ysis To the Editor: The article by Seifert, Steigerwald, and Cliff (A&R 18507-5 12, 1975) describing resorption of the mandible i n patients with progressive systemic sclerosis prompts us to report a similar observation in a patient with vinyl chloride acro-osteolysis. The patient was a 36-year-old male Caucasian who had worked for 6 years in the manufacture of polyvinyl chloride. Initially he was a reactor cleaner and subsequently he worked in close contact with the reactors, although he did not actually enter them. After 3 years he developed progressive Raynaud’s phenomenon and instability of his fingertips. There was gradual thickening and coarsening of the skin with generalized weakness and severe disability. Apart from finger changes there was gross thickening of the skin of the hands, forearms, upper arms, face, and around the angles of the jaw. He also suffered marked limitation in opening his mouth. X-rays revealed multiple areas of lysis. I n particular, typical changes affected the terminal phalanges Fig 1. Orthopantomogram of the mandible showing erosion 0s bone of the fingers with lysis of the central parts of the phalanges, but with preservation of the bases and tips of these bones. Lytic areas were also seen around the sacroiliac joints, in the phalanges of the great toes, and elsewhere. X-rays of the mandible (Figure 1 ) showed gross erosion of the posterior borders of the ascending rami with complete loss of the angles of the mandible. These erosions extended anteriorly to include the region of the inferior dental canal. There was erosion of the left mandibular condyle, which was reduced to a spike, and erosion of the right coronoid process. The patient was endentulous, with an area of radial lucency around one retained tooth root, but this lucency could well have been inflammatory in origin. Biochemical studies of the collagen in acro-osteolysis are similar to those of progressive systemic sclerosis ( I ) . The similarity of this complication confirms that vinyl chloride acro-osteolysis has many features similar to those of progressive systemic sclerosis and will probably be a useful model in the study of that condition. REFERENCE I . Jayson MIV, Lloyd-Jones K , Black CM, et al: Collagen changes in acro-osteolysis. Proc R SOC Med (in press) MALCOLM I. V . JAYSON, M . D . , M.R.C.P. KENLLOYD-JONES, M.D. DAVID C. BERRY,M . D . MICHAEL BROMIGE, M.D. Departments of Medicine and Dentistry University of Bristol, Harlow Wood Orthopaedic Hospital, and The General Hospital Nottingham, England
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