Collagenofibrotic glomerulopathy in 3 tortoises.

Collagenofibrotic glomerulopathy (CG) is a rare renal disease characterized by the abnormal accumulation of type III collagen within glomeruli. This is the first study to report CG in 3 tortoises housed within the same facility. Histologic analyses revealed eosinophilic glomerular deposits, which had segmental positive immunolabeling with anti-type III collagen antibodies by immunohistochemistry. These deposits were observed in approximately 70% of glomeruli in case 1, 50% in case 2, and 95% in case 3. An ultrastructural examination confirmed that the deposits were comprised of irregularly arranged collagen fibrils with periodic transverse striations mixed with fibrils of a smaller diameter. Additionally, similar deposits were noted in the walls of arterioles in the spleen of case 3. Therefore, CG in tortoises may be a systemic disease.