Endocrine Abstracts

Introduction: Paraganglioma (PGL) is a neuroendocrine tumor derived from extra adrenal autonomic paraganglia with a germinal mutation rate of 30%. Metastatic paraganglioma (MPGL) can only be predicted after evidence of secondary lesions and it can occur in up to 50% of cases. Clinical course is remarkably variable, but 5-year overall survival is generally around 50%. Treatment options include surgical resection, chemotherapy, radiotherapy, and ¹²³I-MIBG. Being a neuroendocrine tumor, PGL usually express somatostatin receptors but somatostatin analogues have been seldomly used in metastatic PGL and its efficacy is not well demonstrated.

Clinical case: We present a 45yr female patient with a 1-month history of right thoracic pain associated with homolateral back pain and upper limb paresthesia. Thoracic CT identified a 6 cm lesion on the right lung apex, with extensive invasion of posterior thoracic wall, D1 and D2 vertebral bodies and vertebral canal. Urinary normetanephrine was markedly increased (7719 pg/ml, RR <600). Tissue biopsy allowed the diagnosis of aggressive PGL with Ki-67 of 15%. PET ⁶⁸Ga-DOTANOC was unremarkable except for the previously known lesion. After alfa-blockade, surgery was performed and then followed by ¹²³I-MIBG (200 mCi). Post-treatment scintigraphy and PET ⁶⁸Ga-DOTANOC identified residual tumor without distant metastasis. After 4 years of loss of follow-up, symptoms returned, and both ¹²³I-MIBG scintigraphy and PET ⁶⁸Ga-DOTANOC identified a 7 cm thoracic lesion and additional bone lesions on multiple vertebrae and iliac bone. The patient underwent a second surgical procedure but had tumor progression 4 months later. Stereotaxic radiotherapy with 49 gray was then given. However, the following PET ⁶⁸Ga-DOTANOC showed new metastatic bone lesions and so we decided to start lanreotide 120 mg every 28 days. After 6-months, all previously known lesions were stable but a new slightly increased uptake was seen at the pleura. So that, we increased lanreotide frequency to every 3 weeks. Since then, 18 months have passed with no evidence of disease progression and she is still on this treatment regimen.

Discussion: To date, metastatic PGL can only be cured by surgical resection. Chemotherapy, radiotherapy and ¹²³I-MIBG are used for disease control. Most recently, peptide receptor radionuclide therapy has shown promising results. Somatostatin analogues such as lanreotide are currently used on gastroenteropancreatic neuroendocrine tumors but its role in PGL treatment is still unclear. This case shows an extraordinary response of MPGL to lanreotide, raising interest in this potential therapeutic weapon for a subset of patients who have still few treatment modalities available.