Adrenal cortical epithelial cysts in two saddleback tamarins (Saguinus fuscicollis).

Adrenal cysts of epithelial origin were found incidentally in the adrenal cortical tissues of two adult female saddleback tamarins. In one case, a small cluster of minor cysts was located at the cortico-medullary border. The cysts were filled with a periodic acid-Schiff (PAS)-positive, amorphous substance and lined by a cuboidal PAS-negative epithelium, which resembled morphologically the ascending Henle's loops of the kidney. These microcysts were thought to be mesonephric remnants. In the second case, two large cysts of 1 to 3 mm diameter extended throughout the entire cortex. The cysts were filled by a watery, PAS-negative fluid and lined by a bi- to multi-layered, cytokeratin-positive epithelium. The basal epithelial layer consisted of cuboidal cells, which became cylindrical to drop-like in appearance towards the cyst lumen. The cysts closely resembled mesothelium-derived adrenal cysts in man. This is the first report of adrenal cysts in non-human primates.