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Adrenal cancer
Diagnosis
CT scans
CT can
reliably distinguish cortical hyperplasia from tumor.
Incidentally discovered adrenal masses found in 1 to 3% of patients
undergoing abdominal scans by computed tomography (CT). Most of
these masses are benign, and adrenal cortical adenomas are 60 times
more common than primary carcinoma.
Criteria suspicious of malignancy
- The typical malignant case is characterized by a large unilateral
adrenal mass with irregular edges.
- Masses less than 3 cm in diameter are usually benign; in
contrast, the probability that the mass is malignant is generally
increased when it measures more than 6 cm. There is uncertainty with
masses measuring 3 to 6 cm and concern that adrenal cortical
carcinomas could be missed in early stages of development.
- The presence of contiguous
adenopathy serves as corroborating evidence.
Rationale
- Targeted CT scans of the adrenal using 3- to 5-mm sections offer the
best resolution and are particularly useful in detecting tumors that
are 1 cm or smaller.
- CT has great
sensitivity (more than 95%); however, it lacks specificity.
- CT can
be used to image the primary tumor plus local and distant metastases
in cancer.
MRI
MRI is able to distinguish among adenoma, carcinoma, and
pheochromocytoma. Signal loss on chemical shift MRI occurs in
adrenal cortical cancer.
- The sensitivity of MRI for distinguishing benign from
malignant masses was 89%, specificity was 99%, and accuracy was
94%.
PET scans
Positron emission tomography (PET) studies have used fluorodeoxyglucose or methionine C 11. A better imaging tracer for adrenal tumors may
be 11C-metomidate. Although this tracer does not distinguish
benign from malignant tumors, the presence of uptake in
extra-adrenal sites may indicate recurrence of disease or metastasis
in patients who have undergone resection of an adrenocortical
carcinoma.
Ultrasonography
This test has less sensitivity in detecting adrenal tumors and is
highly user-dependent in its interpretation and quality of results.
It has particular utility, however, in the follow-up of previously
detected incidentalomas.
Malignant lesions vary in echo texture and are heterogeneous in
appearance, with focal or scattered echopenic or echogenic zones
representing areas of tumor necrosis, hemorrhage, or calcification.
Angiography and adrenal venography
Selective angiography and adrenal venography have a
very small role in the diagnostic workup of adrenal masses. They
may be helpful in identifying smaller lesions and for distinguishing
tumors of the adrenal gland from tumors of the upper pole of the
kidney. Vena caval contrast studies and angiography may provide
additional staging information and allow for a more complete
preoperative assessment.
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Scintigraphy
Most adrenal cortical carcinomas fail to image with
131I-6β-iodomethylnorcholesterol scintigraphy. Because cortisol production suppresses ACTH
secretion and the function of the contralateral adrenal gland,
patients with cortisol-producing adrenal cortical carcinomas fail to
show an image either at the site of the tumor or the contralateral
gland. CT and iodomethylnorcholesterol scintigraphy can be
used together in the diagnosis of small (less than 4 cm) euadrenal
masses. Concordant images (CT image and increased uptake on the same
side) are benign in 100% of cases, whereas discordant images (a CT
tumor image on one side and increased uptake on the contralateral
side) are malignant in 73% of the cases.
Adrenal function tests
Other investigations may include appropriate
endocrine studies. The steroid profile in serum or urine can
help distinguish between benign and malignant adrenal cortical
tumors because of the presence of intermediary precursors in the
steroid biosynthesis pathway or their metabolites in patients with
malignant neoplasms.
Fine-needle aspiration and core biopsy
Never perform fine-needle aspirations on any adrenal mass without
first definitively excluding a pheochromocytoma; otherwise, the
procedure may precipitate a potentially fatal crisis.
Because the histologic analysis of these masses may be unreliable,
fine and/or core tissue needle aspiration biopsies (percutaneous
route) generally are not recommended except for possible metastatic
deposits.
The fine-needle and/or percutaneous core biopsies may be CT-guided
or ultrasound-guided. Presently, the only setting where this is
justified is in the evaluation of patients with a known malignancy,
in order to exclude adrenal metastases.
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