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T1-weighted gadolinium-enhanced MRI of the pituitary. A hypointense lesion of the neurohypophysis is indicated.
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Figure 1: T1-weighted gadolinium-enhanced MRI of the pituitary. A hypointense lesion of the neurohypophysis is indicated.

Mentions: In September 2003, a 41-year-old man presented with unexplained progressive weight gain, facial plethora, tremor, sweating, newly-diagnosed hypertension, hypokalemia, and diabetes mellitus. Physical examination revealed a blood pressure of 170/110 mm Hg, pulse of 88 bpm, thyroid enlargement, and cushingoid features including striae, moon face, central obesity, and a buffalo hump. Laboratory testing showed hyperthyroidism (undetectable TSH, free T4 of 32 pmol/L (normal: 12–22), free T3 of 9 pmol/L (normal: 3.95–6.80)) and increased 24 h urinary free cortisol (7579 nmol per day, normal range: 22–212). Thyroid ultrasound showed a multinodular goiter. A Tc-99m-pertechnetate thyroid scan revealed increased uptake in an area of the left thyroid gland corresponding to an autonomous adenoma. Serum calcitonin was within the normal range. Basal serum cortisol and plasma ACTH were significantly elevated at 1307 nmol/l (normal range: 187–724) and 22.51 pmol/l (1.98–11.4), respectively. After a 2-mg overnight dexamethasone suppression test, serum cortisol was still at 1132 nmol/l (normal, < 80). Midnight cortisol was elevated at 847 nmol/l. After an overnight 8-mg dexamethasone suppression test, serum cortisol decreased by 38 % of basal values suggesting ectopic ACTH-secretion (EAS). CRH stimulated serum cortisol and plasma ACTH to less than 4 % of basal values. Inferior petrosal sinus sampling (IPSS) did not show significant central-to-peripheral ACTH gradients. Ectopic ACTH syndrome was diagnosed. Computed tomography (CT) scans at first presentation did not show pulmonary and/or abdominal tumors, however, both adrenals appeared enlarged with the left gland showing a tumor of 1 cm size. A magnetic resonance imaging (MRI) scan of the head demonstrated a small 3 mm hypointense and hypoenhancing lesion of the neurohypophysis (Fig. 1). An 111In-pentetreotide scan showed radiotracer enrichment in the left thyroid gland consistent with the region of the autonomous adenoma and faint focal octreotide enhancement in the abdomen which was interpreted to be nonspecific because of lacking correlation on CT scan and changing location of enhancement between early and late scan (Fig. 2). Positron emission tomography (PET) with 18F- fluorodeoxyglucose (FDG) and colonoscopy showed normal results. Thyroid antibodies were negative, supporting the scintigraphic finding that hyperthyroidism in this patient was caused by an autonomous adenoma. Given the scenario of EAS and an octreoscan being reliably positive only in the left thyroid gland, we decided to perform a left-sided hemithyroidectomy and subtotal resection of the right gland after treatment with methimazole, although basal calcitonin was normal and pentagastrin stimulation could not be performed because it was not available. Extensive pathological workup of the thyroid specimen did not reveal an ACTH-producing endocrine tumor but a 2 mm sized benign nodule on the right side, and 2 benign nodules (1 cm and 2 cm in diameter, respectively) within the left thyroid gland.

Ectopic Cushing' syndrome caused by a neuroendocrine carcinoma of the mesentery

Fasshauer M, Lincke T, Witzigmann H, Kluge R, Tannapfel A, Moche M, Buchfelder M, Petersenn S, Kratzsch J, Paschke R, Koch CA - BMC Cancer (2006)

Bottom Line: Surgical removal of the pituitary lesion within the posterior lobe did not improve hypercortisolism and we continued to treat the patient with metyrapone to block cortisol production.After removal of this carcinoma, the patient improved clinically.Laboratory testing confirmed remission of hypercortisolism.

Affiliation: Division of Endocrinology and Nephrology, University of Leipzig, Philipp-Rosenthalstr. 27, 04103 Leipzig, Germany. mathias.fasshauer@medizin.uni-leipzig.de

ABSTRACT

Background: ACTH overproduction within the pituitary gland or ectopically leads to hypercortisolism. Here, we report the first case of Cushing' syndrome caused by an ectopic ACTH-secreting neuroendocrine carcinoma of the mesentery. Moreover, diagnostic procedures and pitfalls associated with ectopic ACTH-secreting tumors are demonstrated and discussed.

Case presentation: A 41 year-old man presented with clinical features and biochemical tests suggestive of ectopic Cushing's syndrome. First, subtotal thyroidectomy was performed without remission of hypercortisolism, because an octreotide scan showed increased activity in the left thyroid gland and an ultrasound revealed nodules in both thyroid lobes one of which was autonomous. In addition, the patient had a 3 mm hypoenhancing lesion of the neurohypophysis and a 1 cm large adrenal tumor. Surgical removal of the pituitary lesion within the posterior lobe did not improve hypercortisolism and we continued to treat the patient with metyrapone to block cortisol production. At 18-months follow-up from initial presentation, we detected an ACTH-producing neuroendocrine carcinoma of the mesentery by using a combination of octreotide scan, computed tomography scan, and positron emission tomography. Intraoperatively, use of a gamma probe after administration of radiolabeled (111)In-pentetreotide helped identify the mesenteric neuroendocrine tumor. After removal of this carcinoma, the patient improved clinically. Laboratory testing confirmed remission of hypercortisolism. An octreotide scan 7 months after surgery showed normal results.

Conclusion: This case underscores the diagnostic challenge in identifying an ectopic ACTH-producing tumor and the pluripotency of cells, in this case of mesenteric cells that can start producing and secreting ACTH. It thereby helps elucidate the pathogenesis of neuroendocrine tumors. This case also suggests that patients with ectopic Cushing's syndrome and an octreotide scan positive in atypical locations may benefit from explorative radioguided surgery using (111)In-pentetreotide and a gamma probe.

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