Recommendations for proceeding to FNA to evaluate for malignancy differ among subspecialty societies. Generally, nodules larger than 1 cm or nodules smaller than 1 cm with risk factors for malignancy should be referred for FNA.2,7
If diagnostic workup identifies a patient with hyperthyroidism due to an autonomously functional nodule or a nodule that may be at high risk for malignancy, it is appropriate to involve an endocrinologist and possibly a surgical subspecialist prior to discharge. Management of hyperthyroidism can include starting antithyroid agents (methimazole or propylthiouracil), radioactive iodine ablation, or referral for surgery.
Preparation for discharge of the patient whose incidentaloma is nonfunctional or does not appear to be malignant should include appointments to recheck thyroid hormone levels, including TSH as well as a thyroid ultrasound within one year of the initial discovery.
Adrenal incidentaloma. The prevalence of AIs found by CT of the abdomen ranges from 0.4% to 4%, while autopsy studies have found a prevalence of 1.4% to 9% with increasing prevalence with age.2,9,10 The majority of AIs are benign and nonfunctioning adenomas, in the absence of known malignancy. Other differential diagnoses include Cushing’s syndrome, pheochromocytoma, adrenocortical adenoma, aldosteronoma, and metastatic lesions.
Because functioning adrenal incidentalomas may be clinically silent, any patient found with an AI must undergo biochemical workup as part of their evaluation to assess for pheochromocytoma, Cushing’s syndrome, and if he or she has a history of hypertension or hyperaldosteronism (Conn’s syndrome). Table 3 outlines the approach for characterizing adrenal incidentalomas.2,11,12 An important point is that imaging studies are not useful in distinguishing a functioning versus nonfunctioning tumor but rather can help to discriminate malignant lesions.11
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Table 3. Characterization of the adrenal incidentaloma2,11
Inpatient surgical consult for resection is indicated if the patient is found to have pheochromocytoma, clinically apparent functioning adrenocortical adenoma, or a tumor size greater than 4 cm. Consultation with an endocrinologist is also recommended if biochemical tests are positive. If the diagnostic workup leads to suspicion for infection or metastatic disease, the patient should be referred for FNA.2,12
For patients whose lesions do not require surgical resection, repeat CT scan of the abdomen is recommended six months from the initial finding. Hospitalists should also arrange for the patient to repeat biochemical testing, including an overnight dexamethasone test.12,13
Back to the Case
The patient underwent biochemical testing and was found to have normal levels of plasma-free metanephrines, a plasma aldosterone, plasma renin activity ratio less than 20, and a serum cortisol level of 7 mg/dL after his overnight dexamethasone suppression test. The 24-hour urine collection for free cortisol revealed elevated levels of cortisol in the urine, and the ACTH level was low.
Endocrinology and endocrine surgery teams were consulted, and recommended surgical resection. After surgical resection of his tumor, the patient was started on glucocorticoid replacement and was discharged with a follow-up appointment with endocrinology.
Bottom Line
An inpatient approach to endocrine incidentalomas should include characterization of the clinical signs and symptoms, size, function, and malignant potential of the lesion. Based on this, inpatient surgical or medical management can be determined. Post-discharge management should include arrangements for surveillance testing and follow-up with appropriate subspecialists.
Dr. Tad-y is assistant professor of medicine and a hospitalist at the University of Colorado Denver.
