To the Editor:
Please “bear” with me, but the diagnosis offered by Wegner, et al1 is challenged. The wrist alterations in the presented radiologic image1 are identical to those noted in Figure 1 presented here, except that in this instance, it has progressed to partial fusion. However, neither this radiograph nor the one in the Wegner, et al1 report actually represents rheumatoid arthritis (RA), and Figure 1 here is that of the manus of a black bear, Ursus americanus OMNH (Oklahoma Museum of Natural History) 33-0-S1. Humans and bears share similar wrist anatomy. Relative sparing of metacarpophalangeal joints and erosive changes in distal interphalangeal joints would be distinctly unusual in RA, but are classic for those of spondyloarthropathy (SpA), especially of the psoriatic variety2. While there has been discussion about splitting or lumping peripherally limited erosive disease3, the variety of erosive arthritis that occurs in non-human mammals4 and specifically in bears5 has been clearly identified as SpA. In the case sited herein, syndesmophytes were present and erosive disease was also noted in 1 elbow. There is actually no evidence for occurrence of RA in non-human animals, if the authors considered the alternative diagnosis of SpA and not just ankylosing spondylitis.
Dorsal (left) and ventral (right) views of right wrist of OMNH 33-0-S1 Ursus americanus. Visible is loss of carpal bones with fusion of residual row. OMNH: Oklahoma Museum of Natural History.
