Calcium oxalate crystals in the kidney and thyroid of leprosy patients.

The presence of calcium oxalate crysta.ls in the human kidney ,vas reported 111 1959 ( 15) . This was later follo'Ned by many studies in which the same kind ?f crystals were found in the human thYl:Old (17), retina oculi (5, 18), and myocardIUm ( 2). These ealciu m oxal ate crystals ha ~e been thought to have a different pathologIC meaning from crystal formation in primary oxalosis. There have been discussions on the relationship between this kind of crystal and malignant tumor (:\) and urcmia ( I, 7). . In the course of a study of 149 autopsi es of leprosy patients performed in two Japanese national leprosaria ( Keifu-en Leprosarium and Komyo-en Lcprosarium ) during 1943-1967, similar calcium oxalate crystals were found in 46 cases of leprosy patients in the kidn ey and I or thyroid. Although a group of autopsy cases from the 1960's in this study have shown crystals at a higher rate in the thyroid with distinct correlation with malignant tumors, most of the cases with crystals in the kidney and l or thyroid were not related to uremia. ~s similar crys tals w('ru found frequently 111 autopsy cases at general hospitals , :he presence of these crystals is not a specIfic finding for leprosy (10). In summarizing the histopathologic fin~­ ings of 46 cases of leprosy, a hypothesIs as to the pathogenesis of the crystals is presented together with a discussion of th~ pathologic meaning of such crystal depOSItion in leprosy.