Endocrine Abstracts

Introduction: Pheochromocytomas/paragangliomas are rare neuroendocrine tumors. Although mostly sporadic, about 1/3 of the cases correspond to inherited autosomal dominant syndromes, often associated with germline mutations of the SDHD, SDHC and SDHB genes. The association with the SDHAF2(SDH5) gene has been recently discovered, with only few cases published worldwide, and it presents as a paraganglioma of the head and neck, without previous known description of other locations. Its natural history is still unclear, making clinical follow-up truly challenging.

Case report: Forty seven year-old woman, referred to the Endocrinology Department in 2003 by right adrenal nodule of 3 cm, an incidental CT finding. MRI confirmed right suprarenal nodule, well delimited, hypercaptant, with hyperintense signal on T2-weighted-images, that could represent pheochromocytoma. Hormonal study was compatible with non-secretory nodule: metanephrine 96.5 μg/24 h (52–341), normetanephrine 273.1 μg/24 h (88–444), dopamine 234.6 μg/24 h (65–400), adrenaline 2.7 ug/24 h (5–20), noradrenaline 31.7 ug/24 h(15–80), vanillylmandelic acid (VMA) 5.2 mg/24 h (1.4–6.5) and homovanillic acid(HVA) 4.2 mg/24 h(<8.3) in 24-h-urine. The scintigraphy with I131-norcholesterol documented nonfunctioning lesion, aspiration biopsy was suggestive of pheochromocytoma and scintigraphy with I123-MIBG was negative. The patient was proposed to right adrenalectomy, which she declined. She remained under clinical, analytical and imaging surveillance. In the 14-year follow-up with annual CT and MRI, a nodule reduction of 3 cm to 1.7 cm of greater-axis was observed. A PET-FDG and a PET-68Ga-DOTA-NOC were performed in 2012 and were both negative. Analytic control remained without changes. In 2014, the molecular genetics analysis revealed an heterozygotic mutation in the SDHAF2 gene (c.97C>T, p.Arg33Cys), also confirmed in another Genetics Department. At that time, the patient mentioned a cousin living in France probably affected. In 2017, a second review of histological slides maintained the diagnosis of pheochromocytoma. The patient is under surveillance, asymptomatic and without directed therapy.

Conclusion: The authors describe a rare case of isolated pheochromocytoma associated with mutation in the SDHAF2 gene, in a patient who chose not to undergo surgery and represents a true therapeutic and follow-up challenge, given the absence in the literature of case reports with similar clinical presentation and limited knowledge of its long-term evolution. Recent studies suggest that mutation analysis of the SDHAF2 gene is warranted in very young patients with isolated head and neck paraganglioma without mutations in SDHD, SDHC or SDHB genes, and in individuals with family history that are negative for mutations in all other risk genes.