Endocrinol Metab.  2015 Dec;30(4):481-487. 10.3803/EnM.2015.30.4.481.

A 5-Year Prospective Follow-Up Study of Lipid-Rich Adrenal Incidentalomas: No Tumor Growth or Development of Hormonal Hypersecretion

• Schalin-Jantti C
• Raade M
• Hamalainen E
• Sane T

• KMID: 2169656
• DOI: http://doi.org/10.3803/EnM.2015.30.4.481

Abstract

BACKGROUND
Current guidelines for follow-up of adrenal incidentalomas are extensive and hampered by lack of follow-up studies. We tested the hypothesis that small lipid-rich adrenal incidentalomas, initially characterized by tumor size <40 mm and <10 Hounsfield units (HUs) on unenhanced computed tomography (CT) may not demonstrate excessive growth/hormonal hypersecretion on follow-up.
METHODS
Sixty-nine incidentalomas in 56 patients were restudied with unenhanced CT and screening for hypercortisolism (dexamethasone suppression test [DST], plasma adrenocorticotropic hormone) and pheochromocytoma (24-hour urinary metanephrines and normetanephrines) 5 years later. Primary hyperaldosteronism was excluded at base-line.
RESULTS
Tumor (n=69) size was similar before and after 5 years follow-up (19+/-6 mm vs. 20+/-7 mm). Mean tumor growth was 1+/-2 mm. Largest increase in tumor size was 8 mm, this tumor was surgically removed and histopathology confirmed cortical adenoma. DST was normal in 54 patients and two patients (3.6%) were still characterized by subclinical hypercortisolism. Initial tumor size was >20 mm for the patient with largest tumor growth and those with subclinical hypercortisolism. All patients had normal 24-hour urinary metanephrines and normetanephrines. Low attenuation (<10 HU) was demonstrated in 97% of 67 masses re-evaluated with unenhanced CT.
CONCLUSION
None of the patients developed clinically relevant tumor growth or new subclinical hypercortisolism. Biochemical screening for pheochromocytoma in incidentalomas demonstrating <10 HU on unenhanced CT is not needed. For such incidentalomas <40 mm, it seems sufficient to perform control CT and screen for hypercortisolism after 5 years.

Keyword

Adrenal incidentaloma; Follow-up; Computed tomography; Pheochromocytoma; Metanephrine; Normetanephrine

MeSH Terms

Adenoma
Cushing Syndrome
Follow-Up Studies*
Humans
Hyperaldosteronism
Mass Screening
Metanephrine
Normetanephrine
Pheochromocytoma
Plasma
Prospective Studies*
Metanephrine
Normetanephrine

Figure

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  Fig. 1 The original study cohort with adrenal incidentaloma and number of patients and adrenal masses eligible for the 5-year follow-up study.

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  Fig. 2 Distribution of tumor size changes after 5 years follow-up.

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  Fig. 3 Unenhanced computed tomography of a typical adrenal incidentaloma (arrow) on the right. Placement of region of interest (ROI) cursor for measurement of Hounsfield units (HU) is also shown. HU was negative.

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