Amyloidosis in Rheumatoid Arthritis Investigated by Means of Rectal Biopsy.

The types of disease associated with secondary amyloidosis have undergone considerable change in recent years. Largely because of modern antibiotic treatment, amyloidosis associated with tuberculosis, osteomyelitis, chronic lung disease, and syphilis is now rarely seen. For this reason rheumatoid arthritis is now one of the commonest causes of secondary amyloidosis. Although amyloidosis may be suspected on clinical or biochemical grounds, a definite diagnosis can only be made by tissue biopsy or post mortem. Most investigations of the incidence of amyloidosis in patients with rheumatoid arthritis have been based on post mortem studies. Missen and Taylor (1956), in reviewing the literature, found a wide variation in the reported incidence. The highest incidence-60 per cent.-was reported by Teilum and Lindahl (1954), whereas Rosenberg, Baggenstoss, and Hench (1943) had found only one case of amyloidosis in thirty necropsies on patients with rheumatoid arthritis (3 3 per cent.). This marked discrepancy reveals the limitations inherent in deriving the incidence of a disease from "selected" necropsies. Rectal biopsy has recently been advocated by several authors as the best and most convenient method for the diagnosis of amyloidosis. Blum and Sohar (1962) obtained positive results in 75 per cent. of a series of 62 patients with amyloidosis already diagnosed by other methods. In this paper we describe the results of rectal biopsy used as a screening test for amyloidosis in a random population of patients with rheumatoid arthritis, the majority of whom were currently under treatment at the Oxford Regional Rheumatism Centre. In addition to the rectal biopsy, other clinical and laboratory data were collected from each patient included in the study.