Detection of adrenal and retroperitoneal masses in a general health examination system

To investigate the detection rate of adrenal and retroperitoneal masses other than kidney diseases in a general health examination system.

From May 1991 through February 1996, 41,357 subjects participated in the general health examination system in our hospital. Approximately 80% of participants were 40 to 59 years old. For all participants, transabdominal ultrasound (US) was performed by five expert examiners using an Aloka SSD-650 with a 3.5-MHz convex-type transducer. When US revealed abnormal lesions on the adrenal gland and in the retroperitoneal space, we recommended that participants be examined with computed tomography (CT), with a slice width of 5 mm.

Forty-three participants (0.1%) had abnormal findings on US. Of the 28 of those who underwent CT examination to confirm the lesions, 12 had adrenal and retroperitoneal masses. The detection rate was 0.029% of total participants and 42.9% of those who underwent CT examination. Clinical diagnoses were primary aldosteronism (1), preclinical Cushing syndrome (2), nonfunctioning adrenocortical tumor (5), pheochromocytoma (1), ganglioneuroma (1), adrenal cyst (1), and retroperitoneal neurinoma (1). False-positive results were dominant on the left side of the body (right 3, left 13). A deformed or accessory spleen (3), a cyst on the upper pole of the kidney (2), bowel air (2), and a pancreatic cyst (1) were misdiagnosed as adrenal lesions on US.

The low detection rate of adrenal and retroperitoneal masses by US does not support screening for the diseases in healthy subjects. However, if it is done as part of a general health examination, examiners should attentively observe not only the kidneys but also the adrenal gland and retroperitoneal space because clinically important diseases may be detected.