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1999 Resident Poster Competition

Darin Brimhall D.O.
Washington University
Acute Cushing's Syndrome as a Result of Ectopic Acth Secretion

Third Place
Clinical Division

Darin Brimhall D.O.: Acute Cushing's Syndrome as a Result of Ectopic Acth Secretion

Learning Objectives: (1) Recognize the clinical features and establish the diagnosis of Cushing's syndrome, (2) Localize ectopic ACTH-secreting tumors in Cushing's syndrome with the use of In-Pentetreotide (octreotide) scintigraphy.

Case: A 39-year-old woman is admitted with generalized weakness and cramps, and a potassium level 1.7 mmol/L. The patient also complained of two months of facial fullness, hirsutism, acne, hair thinning, dysesthesia, irregular menstruation, hyperpigmentation of her face and upper trunk, and dizziness. The patient has no known past history of diabetes of hypertension, but was found to have a random blood sugar of 430 mg/dL and had developed hypertension.

Labs: morning plasma cortisol level 63 m /dL (normal 5-25 m g/dL), free urinary cortisol level 3100 m /24 hours (normal 20-100 m gh/24-4 and 3400 m g/24-4 after 2.0 mg and 8.0 mg dexamethasone respectively. Fasting morning ACTH level 181.1 pg/ml (normal <60 pg/ml), repeat level after 8.0 mg dexamethasone 303 pg/ml. Urinary 17-ketosteroids 47 mg/24-h (normal 5-15 mg/24-h).

MRI of the head and pituitary ruled out pituitary microadenoma. CT of the chest & abdomen were performed to evaluate the adrenal glands and rule out tumor. The results showed bilateral adrenal enlargement and multiple hepatic "hemangiomas." Tumor localization SPECT imaging using In-Pentetreotide (octreotide) scintigraphy was then obtained to evaluate for ectopic-ACTH secreting lesion. This revealed abnormal accumulation of tracer in a mass anterior to the aorta adjacent to the uncal process of the pancreas. Upon retrospective evaluation of the abdominal CT, a small mass was observed.

She underwent surgery which revealed unresectable islet cell carcinoma and multiple hepatic metastases. Bilateral adrenalectomy was performed to control the Cushing's syndrome.

Discussion: 5-10% of all cases of Cushing's syndrome are caused by ectopic ACTH secretion. The efficacy of In-Pentetreotide scintigraphy in localizing ectopic ACTH-secreting tumors in Cushing's syndrome is controversial. We present a case of the usefulness of somatostatin receptor scintigraphy in localizing this patient's lesion.

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