Poster Presentation ESA-SRB 2023 in conjunction with ENSA

We present the case of a 26-year-old male with a 39mm right adrenal incidentaloma, with elevated plasma metanephrines and normetanephrines (Table 1) suggestive of phaeochromocytoma. He also had multiple TIRADS 3-4 thyroid nodules, with biopsy features highly suspicious for medullary thyroid carcinoma (MTC). Calcitonin and CEA levels were also elevated (Table 1). Concerningly, an adrenal MRI showed multiple sub-centimetre intrahepatic lesions, highly suspicious for metastases with a differential diagnosis of haemangiomata. The main concern was for metastatic phaeochromocytoma which could affect haemodynamic stability during planned operative management. Following multidisciplinary discussion, the liver lesions were felt to be more likely metastatic MTC than phaeochromocytoma given the elevated calcitonin and CEA, with known cervical nodal metastasis. As such, following medical optimisation with alpha- and beta-blockade, the patient underwent right adrenalectomy, followed by thyroidectomy one month later. Plasma metanephrines normalised following adrenalectomy, and histology confirmed the presence of a phaeochromocytoma. Somewhat unexpectedly, there was loss of succinate dehydrogenase B (SDHB) expression. Histology of the thyroid confirmed the diagnosis of MTC with involvement of 6/29 lymph nodes resected. Post-operative calcitonin and CEA reduced substantially but remained elevated, suggestive of persistent tumour burden. The findings of a phaeochromocytoma and MTC are suspicious for multiple endocrine neoplasia type 2. The loss of SDHB expression in the phaeochromocytoma also raises the possibility of SDHB mutation. There is no known family history of thyroid, parathyroid, or adrenal malignancies or paragangliomas. SDHB mutations can predispose to non-medullary thyroid cancers (1), but not typically MTC. To our knowledge, there is one case report of a 60-year-old woman with MTC who had a SDHB gene deletion, with no underlying RET mutation (2). There are no cases of RET and SDHB mutation co-expression in patients with phaeochromocytomas. We eagerly await results of genetic testing in our patient.