What Is the Best Approach for the Evaluation and Management of Endocrine Incidentalomas?

Case

A 54-year-old man with a history of hypertension treated with hydrocholorothiazide and Type 2 diabetes mellitus is admitted with abdominal pain and found to have an incidental 2.1-cm left adrenal mass on CT scan of the abdomen. He denies symptoms of headache, palpitations, weight gain, or muscle weakness. His exam is significant for mildly elevated blood pressure. What is the best approach for evaluation and management of this incidental finding?

Overview

Incidentalomas are mass lesions that are inadvertently discovered during radiolographic diagnostic testing or treatment for other clinical conditions that are unrelated to the incidental mass. In recent decades, improvements in radiographic diagnostic techniques and sensitivity have led to increasing discovery of incidental lesions that are often in the absence of clinical signs or symptoms.1 Three commonly discovered lesions by hospitalists are pituitary, thyroid, and adrenal incidentalomas.2 The concerns associated with these findings relate to the potential for dysfunctional hormone secretion or malignancy.

Patients found with pituitary incidentalomas can be susceptible to several types of adverse outcomes: hormonal hypersecretion, hypopituitarism, neurologic morbidity due to tumor size, and malignancy in rare cases. Thyroid incidentalomas are impalpable nodules discovered in the setting of ultrasound or cross-sectional neck scans, such as positron emission tomography (PET) scans. Discovery of a thyroid incidentaloma raises concern for thyroid malignancy.3 The increased use of abdominal ultrasound, CT scans, and MRI has fueled the growing incidence of adrenal incidentalomas (AIs).

The discovery of an endocrine incidentaloma in the inpatient setting warrants a systematic approach that includes both diagnostic and potentially therapeutic management. A hospitalist should consider an approach that includes (see Table 1):

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Table 1. General inpatient approach to endocrine incidentalomas
  1. Characterization of the incidentaloma, including clinical signs and symptoms, size, hormonal function, and malignant potential;
  2. Immediate management, including medical versus surgical treatment; and
  3. Post-discharge management, including monitoring.

Review of the Data

Pituitary incidentalomas. The prevalence of pituitary incidentalomas found by CT ranges from 3.7% to 20%, while the prevalence found by MRI approximates 10%. Autopsy studies have revealed a prevalence ranging from 1.5% to 26.7% for adenomas less than 10 mm, considered to be microadenomas. Broad categories of etiologies should be considered: pituitary adenoma, nonpituitary tumors, vascular lesions, infiltrative disorders, and others (see Table 2). The majority of pituitary adenomas secrete prolactin (30% to 40%) or are nonsecreting (30% to 40%). Adenomas secreting adrenocorticotropin hormone (ACTH, 2% to 10%), growth hormone (GH, 2% to 10%), thyroid-stimulating hormone (TSH, <1%), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) are much less common.2 Significant morbidity and premature mortality are associated with hyperprolactinemia, acromegaly (growth hormone excess), Cushing’s syndrome, and hyperthyroidism. Additionally, up to 41% of patients with macroadenomas were found to have varying degrees of hypopituitarism due to compression of the hypothalamus, the hypothalamic-pituitary stalk, or the pituitary itself.4

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