Endocrine Abstracts

Background: In 2016, a prospective study conducted by our team found a prevalence of 7.7% of pheochromocytomas (Pheo) in patients with neurofibromatosis type 1 (NF1) if systematic screening including free metanephrines measurement (DMX) and abdominal imaging was performed. Half of Pheo were secreting, with 16% being symptomatic. This suggested the benefit of a systematic screening by abdominal imaging and DMX assay. The objective of this study was to evaluate the impact of systematic screening in a large cohort of NF1 patients.

Methods: This was an observational retrospective study of NF1 patients followed in the Lyon reference center Leon Berard since 1990 and explored at the Lyon university hospital until August 2023. The files were screened for a history of Pheo and diagnostic circumstances, biological and morphological characteristics, therapeutic modalities and evolution were collected.

Results: The whole cohort comprised 1594 NF1 patients, from whom 585 had undergone abdominal imaging at least once from the age of 25. Forty-eight patients were diagnosed with a Pheo and 1 with an extra-adrenal paraganglioma (PPGL). Prevalence of Pheo/PPGLs was 8.4% in the imaging population and 3% for the whole cohort. Nineteen Pheo/PPGLs were diagnosed on systematic screening (Screening Group (SG)) and 27 were diagnosed either incidentally (n=10) or because of symptoms (n=17) (Non Screening Group (NSG)). Median age at diagnosis was 44 years in both groups, with more men in SG (58%) than in NSG (26%; p=0,037). In SG, 26.3% of patients were symptomatic vs 84.6% in NSG, (P<0.001) while the proportion of secreting Pheo (DMX >2N) was 66.7% in SG, vs 86.4% in NSG (P=0.253). None patient of SG had a Pheo >4 cm vs 24% in NSG (P=0.072). Bilateral Pheo were found in 16.7% of cases in SG vs 42.9% in NSG (P=0.489), all were synchronous in SG vs 43% in NSG. None SG patient was metastatic vs 8% (n=2) in NSG. The number of surgeries was equivalent in both groups; four patients had not been operated on yet. Sparing surgery has been performed in 26.7% of patients in SG (n=4) vs 4.2% (n=1) in NSG (P=0.062).

Conclusion: Systematic screening for Pheo could allow diagnosis of smaller lesions, fewer metastatic and more often asymptomatic despite secreting. It led to more conservatives surgeries.