In medicine, an incidentaloma is a tumor (-oma) found by coincidence (incidental) without clinical symptoms and suspicion. It is a common problem: up to 7% of all patients over 60 may harbor a benign growth, often of the adrenal gland, which is detected when diagnostic imaging is used for the analysis of unrelated symptoms. With the increase of "whole-body CT scanning" as part of health screening programs, the chance of finding incidentalomas is expected to increase.

When faced with an unexpected finding on diagnostic imaging, the clinician faces the challenge to prove that the lesion is indeed harmless. Often, some other tests are required to determine the exact nature of an incidentaloma.

Adrenal incidentaloma

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In adrenal gland tumors, a dexamethasone suppression test is often used to detect cortisol excess, and metanephrines or catecholamines for excess of these hormones. Tumors under 3 cm are generally considered benign and are only treated if there are grounds for a diagnosis of Cushing's syndrome or pheochromocytoma (Grumbach et al 2003).

Pituitary incidentaloma

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Autospy series have suggested that pituitary incidentalomas may be quite common. It has been estimated that perhaps 10% of the adult population may harbor such endocrinologically inert lesions (Hall et al). When encountering such a lesion, long term surveillance has been recommended (Molitch). Also baseline pituitary hormonal function needs to be checked, inculding measurements of serum levels of TSH, prolactin, IGF-I (as a test of growth hormone activity), and adrenal function (i.e. dexamethasone suppression test).

Others

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Other organs that can harbor incidentalomas are the liver (often a hemangioma), thyroid, parathyroid, and the kidneys.

Scientific criticism

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The concept of the incidentaloma has been criticized, as such lesions do not have much in common other than the history of an incidental identification and the assumption that they are clinically inert. It has been proposed just to say that such lesions have been "incidentally found." (Miralas et al) The underlying pathology shows no unifying histological concept.

References

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• Grumbach MM, Biller BM, Braunstein GD, Campbell KK, Carney JA, Godley PA, Harris EL, Lee JK, Oertel YC, Posner MC, Schlechte JA, Wieand HS. Management of the clinically inapparent adrenal mass ("incidentaloma"). Ann Intern Med 2003;138:424-9. PMID 12614096.
• Hall WA, Luciano MG, Doppman JL, Patronas NJ, Oldfield EH. Pituitary magnetic resonance imaging in normal human volunteers: occult adenomas in the general population. Ann Intern Med 1994;120:817-20. PMID 8154641
• Molitch ME. Pituitary incidentalomas. Endocrinol Metab Clin North Am 1997;26:725-40. PMID 9429857
• Miralas P, Skandalakis JE. Benign anatomical mistakes: incidentaloma. Ann Surg 2002;68:1026-8. PMID 12455801

Radiology | Endocrinology | Oncology | incidentaloma | Incidentalome