Lung Cancer |

Rapid Onset Ectopic ACTH Syndrome as Initial Presentation of Small Cell Lung Cancer FREE TO VIEW

Asad Shafiq, MD; Shravanti Macherla, MD; Urooj Fatima, MD
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Robert Packer Hospital, Sayre, PA

Chest. 2014;146(4_MeetingAbstracts):646A. doi:10.1378/chest.1992268
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SESSION TITLE: Cancer Student/Resident Case Report Posters I

SESSION TYPE: Medical Student/Resident Case Report

PRESENTED ON: Tuesday, October 28, 2014 at 01:30 PM - 02:30 PM

INTRODUCTION: About 1% of patient with small cell lung cancer (SCLC) have Ectopic ACTH Syndrome (EAS). EAS as initial presentation of SCLC is rare. Hypertension with hypokalemic metabolic alkalosis is a common manifestation in many endocrine disorders but when it is acute in onset and deteriorates rapidly, EAS should be considered. Patients presenting with rapid onset EAS due to SCLC have poor prognosis.<!--EndFragment--><!--EndFragment--><!--EndFragment-->

CASE PRESENTATION: 74-year-old male with 50 pack years smoking history and hypertension presented with fatigue and insomnia for three days. On presentation, he was hypertensive(190/84 mm Hg) but rest of physical exam was unremarkable. Initial work up showed severe metabolic alkalosis(ph 7.65, HCO3 50 mmol/L), hypokalemia(1.9 mEq/L) and elevated transaminases. These values were normal six weeks back. Considering severe metabolic disturbance and uncontrolled hypertension, workup for endocrine disorder was done. Renin and Aldosterone was normal. Low Dose Dexamethasone Suppression Test(LDDST) was 101μg/dl and 24 hour Urinary Free Cortisol(UFC) was 7122 μg per 24 h suggesting Cushing syndrome(CS). High Dose Dexamethasone Suppression test(HDDST) was 108 μg/dl and ACTH was 437 pg/ml suggesting EAS. Chest and Abdominal CT showed 1.6 cm right middle lobe pulmonary nodule with mediastinal and pretracheal lymphadenopathy, bilateral adrenal hyperplasia and hepatomegaly. Mediastinal lymph node biopsy was consistent with small cell neuroendocrine carcinoma with positive TTF 1 stain suggesting pulomnary origin. Patient was treated with ketoconazole with improvement of neurologic symptoms and rapid resolution of hypokalemia and metabolic alkalosis. He was started on chemotherapy which was later stopped due to bone marrow metastasis. He died in three weeks from the onset of symptoms.<!--EndFragment-->

DISCUSSION: Our patient presented acutely with marked hypokalemia and metabolic alkalosis with hypertension, suggestive of mineralocorticoid excess. The typical phenotype of CS was absent and there were no signs of malignancy. CS is diagnosed with at least two abnormal screening tests. In this patient, UFC and LDDST were significantly elevated, confirming CS. He had high ACTH suggesting EAS vs. Cushing Disease(CD). HDDST didn’t suppress cortisol, suggesting EAS. The gold standard for differentiating EAS from CD is Inferior Petrosal Sinus sampling after administration of CRH. A pituitary-peripheral ratio greater than 2 suggests CD.

CONCLUSIONS: Rapid onset of severe hypokalemic metabolic alkalosis should raise suspicion for EAS even when typical malignant features are absent. Although rapid onset EAS due to SCLC carries a poor prognosis, it should still be treated; as it carries significant morbidity and the quality of life improves with treatment.

Reference #1: Ioannis Ilias, Torpy David J, Karel Pacak, et al. Cushing’s syndrome due to ectopic corticotropin secretion twenty years’ experience at the national institutes of health. J Clin Endocrinol Metab. 2005;90(8):4955-4962. doi: 10.1210/jc.2004-2527.

DISCLOSURE: The following authors have nothing to disclose: Asad Shafiq, Shravanti Macherla, Urooj Fatima

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