Morphology and pathogenesis of adrenal cysts.

Adrenal cysts represent a rare condition (approximately 250 cases have been reported). We report two additional cases: the first involved a huge lesion removed surgically and thoroughly studied preoperatively; the second was an incidental autopsy finding. Detailed ultrastructural studies have been made of both cases. We think that the basic cell of origin of the cyst is an endothelial cell lining lymphatic channels. We speculate that the pseudocysts, which have been described as having a fibrous lining, probably were at one time also lymphendothelial but, perhaps due to trauma or repeated bleeding, the major portion of the endothelial lining became replaced by collagen. The primary and secondary cystic malignancies and cases of cysts due to parasites should be classified separately from the adrenal cysts of lymphendothelial origin which probably represent a benign tumor-like overgrowth.