8769 A Case of Metastatic and Catecholamine Producing Bilateral Pheochromocytoma in a Patient with RET Gene Mutation

Abstract Disclosure: R.A. Mayers: None. A. Szafran-Swietlik: None. RET mutation, observed in multiple endocrine neoplasia type 2 syndromes, is implicated in the development of pheochromocytomas of the kinase signaling cluster. Such tumors have lower metastatic risk and adrenergic production compared to the ones from the other clusters. We present a case of a metastatic, bilateral, small and biochemically active pheochromocytoma .This is the case of a 27-year-old man diagnosed with MEN 2A. He underwent total thyroidectomy due to medullary thyroid carcinoma at 2 years old. He was deemed cured and started on levothyroxine replacement. Since then, his plasma metanephrines by liquid chromatography-mass spectrometry and urine metanephrines done in a yearly basis as screening, were always within range of normality. Over the years, he developed substance abuse disorder with use of Kratom and methamphetamines and was admitted in a rehabilitation center multiple times in the last three years. During this time, the patient was reported to be slightly tachycardiac which was initially attributed to the use of substances. On the last year, an echocardiogram done as evaluation of his tachycardia showed an ejection fraction of 35%. Later, his annual metanephrine levels were markedly elevated (free metanephrine: 137 pg/mL and free normetanephrine : 157 pg/mL, normal ranges reported as less than 57 pg/mL and less than 148 pg/mL respectively). Abdominal tomography showed a right adrenal nodule of 1.2 cm and a left adrenal nodule of 1.6 cm, both with more than 10 Hounsfield Units. A Metaiodobenzylguanidine scan revealed a left adrenal nodule of 1.8 cm with diffuse radiotracer uptake, a right adrenal nodule of 1.2 cm with radiotracer activity and 3 subtle areas of focally increased radiotracer activity in the liver, two in left hepatic lobe and other in posterior right upper lobe. He underwent bilateral adrenalectomy with cortical sparring. Pathology results evidenced a left adrenal with a unifocal mass of 1.8 cm and a right adrenal with a mass of 1.2 cm , both without lymphovascular, capsular, local invasion or necrosis, a mitotic rate of 1-2 without atypical mitosis, not encapsulated with clean margins and positive for synaptophysin , chromogranin and S100 stains. An additional mass of 0.7 cm on the right adrenal gland was described with similar characteristics to the described before except for the involvement of the surgical margins. Currently on the literature there are different opinions regarding screening approach for pheochromocytomas in the presence of RET mutations. There are not strong recommendations regarding the use of imaging as a screening tool in this group of patients. It is important to consider that there are cases, as the one described in this report, that might present metastatic disease even with the presence of small pheochromocytomas that belong to the cluster of kinase signaling. Presentation: 6/3/2024