Background: Ectopic Cushing’s syndrome from an ACTH-secreting neuroendocrine tumor (NET) is a rare condition whose onset and disease progression is often more aggressive than other forms of Cushing’s syndrome due to complications from severe hypercortisolism.
Clinical Case: A 75-year old woman presented with profound proximal muscle weakness, severe hypokalemia, Cushingoid features, and biopsy-proven Candida esophagitis. Initial testing was consistent with ACTH-dependent Cushing syndrome: elevated 24 hour urinary cortisol excretion (1,310.54 mcg/24h; n <50 mcg/24h), abnormal 1 mg dexamethasone suppression test (68.3 ug/dL), and elevated ACTH level (200 pg/mL; n: 7.2–63.3 pg/mL). MRI was negative for a pituitary lesion but abdominal CT revealed an 8.8 cm liver mass with biopsy consistent with a well-differentiated neuroendocrine tumor, WHO Grade 2. Subsequent 68Ga-DOTATATE-PET/CT noted DOTATATE uptake in the liver lesion, a 0.9 cm right pulmonary nodule, and the pancreatic tail without CT correlate. Initially, the patient was prescribed mifepristone and spironolactone for hypokalemia. Given her NET of unknown primary, metastatic disease, and immunocompromised state due to hypercortisolism, the patient was not a candidate for surgical resection of her NET but was instead referred for bilateral adrenalectomy. However, she rapidly decompensated from complications of her hypercortisolism prior to surgery. Her weakness progressed to immobility, and she developed acute psychosis manifested as agitation and mutism. The patient was immediately admitted to the hospital where she developed new-onset atrial flutter and myelosuppression requiring multiple transfusions. She underwent urgent bilateral adrenalectomy, but despite surgery, her post-operative course was complicated by hypoxemic respiratory failure and shock. The patient shortly thereafter expired from pulseless electrical activity arrest.
Conclusion: This atypical case of an ectopic ACTH-secreting NET highlights the life-threatening complications associated with severe hypercortisolism, including: opportunistic infection, severe metabolic abnormalities, psychosis, myopathy, and critical illness that can incite myelosuppression and unstable arrhythmias. These patients can quickly deteriorate and are at high risk for mortality. Early diagnosis and swift reversal of their hypercortisolism with bilateral adrenalectomy are oftentimes needed to prevent these potentially fatal complications.