SUN-322 Worsening of Carcinoid Syndrome during Lutetium Therapy in a Patient with Bronchial Carcinoid and Acromegaly

Introduction: Neuroendocrine tumors (NET) are uncommon, particularly when affecting the lungs having an incidence of 0.2 to 2 per 100,000. However, they represent 1-2% of all lung malignancies and up to 30% of all NET. In the context of Multiple Endocrine Neoplasia type 1 (MEN1), bronchial carcinoid account for 2% of tumors and have also been reported in MEN4. Case: A 22 year-old male presented with an incapacitating headache after a dental extraction. Brain MRI showed a 3.3x2.4x1.4 cm lesion, suggestive of pituitary apoplexy. Of note, he had a normal brain MRI performed 20 months before due to mental confusion. He complained of abdominal cramps and diarrhea that started six months before, and had an unexplained weight loss of 10 kg during the last two months. He exhibited mild acromegalic features. On pre-operative evaluation, a routine chest X-ray was performed that showed a central lesion in inferior left pulmonary lobe (ILL). A CT scan revealed a 4.5x4.0x3.5 cm lesion in ILL. On biochemical assessment, he had panhypopituitarism with basal GH levels of 2.05 ng/mL and IGF-I of 823 ng/mL (normal range 99-289). He was submitted to transsphenoidal surgery and the histopathological analysis revealed a somatotropinoma and not somatotroph hyperplasia. A bronchoscopy showed a vegetative and hypervascularized lesion, obstructing the left bronchial segment, compatible with bronchial carcinoid. (18)F-FDG PET CT and (68)Ga-DOTATOC PET CT scans revealed discrete increase in glycolytic metabolism and significant increase of SSTR expression in the ILL lesion, hepatic lesions and multiple bone lesions consistent with a well differentiated metastatic bronchial carcinoid. At baseline, chromogranin A level was 17,906 ng/mL (normal range 25-140), serotonin 806.8mcg/L (normal range 30-200) and urinary 5-hydroxyindolacetic acid 19.3 mg/24h (normal range 2.0-9.0). MEN1 sequencing was negative for mutations. In the post-operative evaluation, IGF-I level fell to 474 and GH was 2.48. Pegvisomant and octreotide LAR were started with normalization of IGF-I levels. Peptide receptor radionuclide therapy (PRRT) was initiated with lutetium worsening dramatically his abdominal pain, which resolved after rescue subcutaneous octreotide and reintroduction of octreotide LAR. Since the second cycle, octreotide LAR has been given after (177)Lu dose. BNP levels are within normal range and the patient has a normal echocardiography. Conclusion: The patient has two NET that can be part of a yet undiagnosed syndrome. Well-differentiated NET may synthesize humoral factors that can cause carcinoid syndrome. Excessive circulating serotonin levels may lead to carcinoid heart disease, diarrhea and cramping. During PRRT, hormone-related crisis can occur as a severe side effect. Therefore, octreotide LAR should not be stopped during Lutetium therapy.