Severe erosive polyarthritis in a human skeleton dated to the early modern period of Japan

A human skeleton apparently afflicted with severe polyarthritis was unearthed from an early modern grave at the Tamukai site in the northernmost part of Honshu in Japan. The bones, likely from a late middle-aged male, showed severe resorptive lesions and ankylosis in many of the peripheral joints. Lesions were found in both bilateral and symmetrical distributions, sometimes accompanied by juxta-articular osteoporosis. Differential diagnoses included either rheumatoid arthritis, psoriatic arthritis, or leprosy, with psoriatic arthritis being the most likely. Whatever the final diagnosis, the identification of arthritis mutilans is clear. Because some bones were missing and a mixture of characteristics of both types of arthritis was evident, it was impossible to make a definitive diagnosis. However, this case is valuable for the severity of the lesions and the rarity of erosive polyarthritis found in archaeological skeletons from an Asian site.