A survey on incidental adrenal tumors in Japan.

A nationwide Japanese survey of 210 cases from 116 collaborating institutions demonstrated a dramatic increase in incidentally detected adrenal tumor from 4 cases in 1980 to 54 in 1988. The most common diagnosis was nonfunctioning cortical adenoma (69 cases), followed by pheochromocytoma (49). A total of 14 malignant tumors (6.7%) and 16 functioning benign cortical lesions was also found. Histological study revealed that functioning tumors were small and found in relatively young female patients, nonfunctioning cortical adenomas were of similar size but found in older patients, and all malignant tumors were larger than 6.5 cm. in diameter and occurred in patients 58 years or younger. These results indicate an increase in the occurrence of incidental adrenal tumor and the complexity of pathology.