adrenal incidentaloma

1. OVERVIEW OF THE
ADRENAL
INCIDENTALOMA

2. Incidentaloma
Definition
 Adrenal incidentalomas are unsuspected
adrenal masses greater than 1 cm in
diameter identified on cross-sectional
imaging performed for seemingly unrelated
causes
 Frequency of adrenal incidentalomas is
relatively high, with reporting an incidence
of approximately 5%

3.  Incidence of the incidental adrenal mass
increases with age,with a risk of less than
0.5% in individuals in their 20s and up to
7% in those 70 years of age or older
 Nearly 20% of adrenal incidentalomas are
found to be potential surgical lesions
 The two characteristics of primary clinical
relevance are imaging and metabolic activity
or functional status

5. Imaging of Adrenal Masses
 Ultrasonography is a suboptimal imaging
modality for detecting and fully
characterizing adrenal lesions
 Ultrasonography is responsible for identifying
individuals with adenomas, right-sided lesions
appear to be more common.

6. Computed Tomography and
Magnetic Resonance Imaging.
 CT and MRI permit cross-sectional and
reconstructed anatomic image
characterization of the adrenals and serve
as the cornerstone for adrenal evaluation.
 Most adrenal incidentalomas are small
homogeneous masses with regular
contours that cannot be immediately given
a pathologic label.

7.  An unenhanced CT scan is the first, and
perhaps single best, and most easily
interpreted test for intracellular lipid and
therefore can diagnose an adrenal
adenoma in more than 70% of cases.
 Low attenuation (<10 HU) on unenhanced
CT corresponds to high intracytoplasmic
lipid content and is diagnostic for an
adrenal adenoma

8.  Despite the high specificity of the 10-HU cutoff,
few low-density (<10 HU) pheochromocytomas
have been reported, underscoring the
importance of a metabolic workup for all
adrenal lesions
 CECT -Irregular margins and an enhancing rim
can be quite specific for malignancy

9. Computed Tomography Washout
Study
 Approximately 30% of adrenal adenomas
exhibit an attenuation of greater than 10 HU
on unenhanced CT owing to their lower
lipid content.
 These “atypical adenomas” are
indistinguishable from nonadenomas on
noncontrast CT density measurements
alone
 Fortunately, lipid-poor adenomas possess
identical properties to lipid-rich adenomas
regarding their rapid loss (washout) of
enhancement after CT contrast load

10.  An absolute percent washout (comparing
noncontrast values with 15-minute
postcontrast density values) of greater than
60%, or a relative percent washout (RPW)
(comparing arterial phase density
measurements with 15-minute postcontrast
density values) of greater than 40% on
delayed (washout) imaging, is indicative of
adenoma

11. MRI
 MRI harnesses the interference between
signal collected from fat and water tissue
to evaluate for intracellular lipid content
 On such opposed phase chemical shift
imaging, signal intensity loss on out-of-
phase sequences, when compared with in-
phase imaging, signifies the presence of
intracellular lipid and definitively identifies
the lesions in question is an adenoma

13.  Nevertheless, CT washout studies are
considered the gold standard and appear
to surpass opposed phase chemical shift
MRI in their sensitivity for identifying
adenomas
 MIBG imaging has a limited role in the routine
evaluation of adrenal incidentalomas.
 FDG PET is best reserved for cases in which
CT imaging and clinical data are inconclusive

14. Biopsy of Adrenal Masses
 The role of adrenal biopsy has been limited
for the followingreasons:
 (1) modern imaging in the context of
clinical characteristics affords superb
diagnostic capabilities,
 (2) histologically,adenomas cannot be
reliably differentiated from adrenal
carcinomas,
 (3) adrenal biopsy is not without risk

15.  Adrenal biopsy should be pursued only
when limitations of imaging have been
reached and when the physician and
patient are certain that the result of biopsy
will influence management.
 When used to differentiate benign from
metastatic disease, adrenal biopsy carries
favorable test characteristics.

16. Size and Growth
 A relationship does exist between the size
of an adrenal lesion and its malignant
potential, with larger masses more likely to
exhibit adverse clinical and pathologic
features
 Masses that exceed 6 cm should be
considered malignant until proven benign,
which usually requires definitive resection.

17.  Although management of masses between 4
cm and 6 cm is controversial, thought leaders
in the field advise that in otherwise healthy
individuals, masses 4 cm or larger should be
resected.
 Kinetics of growth should be followed. The
current recommendation is to resect masses
that grow over 1 cm;

18. Assessment of Function of
Adrenal Masses
 The NIH consensus statement
recommends metabolic testing for all
adrenal incidentalomas
 Current practice is to test all new adrenal
masses for cortisol and catecholamine
hypersecretion. In patients with a history of
hypertension, aldosterone hypersecretion
should also assessed

19. Testing for Cortisol
Hypersecretion
 Three first-line tests are available to screen
patients with incidentalomas for Cushing
syndrome:
 (1)LD-DST,
 (2) a late-night salivary cortisol test, and
 (3) a 24-hour UFC evaluation.

20. Testing for Aldosterone
Hypersecretion
 The screening test of choice for Conn
syndrome is the ratio of morning plasma
aldosterone (ng/dL) to renin (ng/mL/hr).
 An ARR of 20 (some suggest 30) along with
a concomitant aldosterone concentration
above 15 ng/mL is indicative of Conn
syndrome

21. Testing for Catecholamine
hypersecretion
 Free fractionated plasma metanephrines
and the 24-hour urinary fractionated
metanephrine test constitute the mainstay
for pheochromocytoma testing.
 Acetaminophen can produce a false-
positive result owing to cross reactivity in
the assay and should be stopped for at
least 5 days before testing

22. Testing for Adrenal Sex Steroid
Hypersecretion
 Hypersecretion of adrenal sex steroids by
adrenal masses, especially incidentalomas, is
exceedingly rare.
 The most common adrenal mass that
hypersecretes sex steroid is an adrenal
carcinoma that concomitantly exhibits cortisol
hypersecretion
 Routine testing of incidentalomas for sex
hormones is currently not recommended