Rubeanic acid stained liver biopsy demonstrating copper deposits.
Wilson's disease is caused by a genetic disorder, affecting an individual's copper metabolism. A distinguishing characteristic of Wilson's disease is copper accumulation in the liver. Hematoxylin and eosin (H&E) stained tissue slides commonly do not reveal the presence of copper. Copper stains such as rhodanine or rubeanic acid (shown in the image) can be used to positively identify copper in liver biopsy tissue, although quantitative copper studies, performed on formalin-fixed, paraffin-embedded (FFPE) tissue, are more sensitive and helpful to the pathologist. Because other liver diseases may also stain positively for copper, pathologists also review the biopsy for another distinguishing characteristic of Wilson's disease which is the presence of Mallory hyalin. The presence of copper and Mallory hyalin are commonly correlated with the clinical history of the patient to positively diagnose the patient with Wilson's disease.