Adrenal tumors are usually diagnosed by clinical symptoms of hormone excess. The increasing use of ultrasound and computed tomography results in the detection of a substantial number of incidentally discovered adrenal tumors. Most of these tumors are nonfunctional adrenocortical adenomas, but a few cases of subclinical cortisol production in "incidentalomas" have been reported. We investigated prospectively the prevalence of autonomous cortisol production in 68 patients (44 females and 24 males, aged 25-90 yr) with adrenal incidentalomas at our institution. As a screening procedure all patients with incidentalomas underwent an overnight dexamethasone suppression test (1 mg). Patients who failed to suppress serum cortisol below 140 nmol/L (5 micrograms/dL) underwent more comprehensive studies (prolonged dexamethasone suppression test, determination of the diurnal rhythm of cortisol secretion in saliva, and CRH stimulation test). Eight patients (12% of all patients with incidentalomas; 5 females and 3 males, aged 25-71 yr) were finally identified as having cortisol-producing tumors, and the findings in these patients were compared with those of overt Cushing's syndrome in 8 patients (8 females, aged 26-50 yr) suffering from cortisol-producing adrenal adenomas. The tumor size of patients with cortisol-producing incidentalomas ranged from 2-5 cm. No specific signs and symptoms of hypercortisolism were present, but arterial hypertension (seven of eight subjects), diffuse obesity (four of eight subjects), and noninsulin-dependent diabetes mellitus (NIDDM; two of eight subjects) were frequently observed. Baseline cortisol levels were in the normal to upper normal range, whereas baseline ACTH levels were suppressed in five of the eight patients. In none of the patients was serum cortisol suppressible by low dose or high dose dexamethasone. The ACTH and cortisol responses to CRH were normal in two, blunted in one, and suppressed in four patients. Unilateral adrenalectomy was performed in seven patients and resulted in temporary adrenal insufficiency in four of them. After surgery, improvement of arterial hypertension, a permanent weight loss in obese subjects, and a better metabolic control of NIDDM were noted in the majority of patients. The following conclusions were reached. Incidentally diagnosed adrenal tumors with pathological cortisol secretion in otherwise clinically asymptomatic patients are more frequently observed than previously assumed. Adrenocortical insufficiency is a major risk in these patients after adrenalectomy. After surgery, hypertension, obesity, and NIDDM may improve. Patients with asymptomatic adrenal incidentalomas, therefore, should be screened for cortisol production by means of an overnight dexamethasone suppression test.

Bei 23 Frauen und neun Männern im mittleren Alter von 54 (25-73) Jahren wurde bei der Klärung anderer Beschwerden zufällig ein asymptomatischer Nebennierentumor entdeckt. In allen Fällen ließen sich die Tumoren computertomographisch darstellen. Achtmal waren sie beidseits lokalisiert, in je 12 Fällen rechts-oder linksseitig. Der durchschnittliche Tumordurchmesser betrug 3 (1-9) cm. Vier Tumoren (12,5%) wiesen eine endokrine Aktivität auf (ein Phäochromozytom, drei cortisolproduzierende Tumoren). Acht Patienten wurden adrenalektomiert, dabei ergaben sich sechs Nebennierenadenome, ein benignes Phäochromozytom und ein Ganglioneurom. Eine Feinnadelbiopsie wurde bei zwei Patienten vorgenommen, der zytologische Befund war benigne. Computertomographische Verlaufskontrollen bei elf (34,4%) der nicht-operierten Patienten 6-48 Monate (im Mittel 14 Monate) später zeigten bei keinem der Patienten eine Größenzunahme des Tumors. Daher erscheint es bei zufällig diagnostizierten Nebennierentumoren gerechtfertigt, zunächst einmal den Verlauf zu beobachten, da gutartige Prozesse offensichtlich weitaus häufiger sind als maligne. Bei einem Tumordurchmesser von mehr als 6 cm ist jedoch wegen des Malignitätsrisikos eine Adrenalektomie durchzuführen.