Pheochromocytomas are diagnosed incidentally and at older age in neurofibromatosis type 1

IntroductionGuidelines do not currently recommend routine systematic hormonal screening for pheochromocytoma (PHEO) in all/normotensive patients with neurofibromatosis type 1 (NF1), in contrast to other PHEO-predisposing genetic syndromes such as Von Hippel-Lindau syndrome and multiple endocrine neoplasia type 2. ObjectivesTo characterize and compare parameters of PHEO in patients with NF1 to patients with or without other germline mutations. MethodsA retrospective chart review of patients with histologically proven PHEO at the Centre hospitalier de l'Universite de Montreal from 2000 through 2015. ResultsNeurofibromatosis type 1 was diagnosed clinically in nine patients in our cohort of 145 PHEO (62%). The mean age at diagnosis was 48 14 years, and seven patients had hypertension. No PHEO was diagnosed by systematic clinical screening. The mode of presentation was adrenal incidentalomas in five patients. Urinary metanephrines were elevated in 5/9 cases. Mean tumour diameter was 35 cm (min-max 15-125 cm). One had bilateral PHEO and none were malignant to date. Statistically significant differences were noted when comparing PHEO in NF1 to other genetic syndromes (n = 20), in terms of age at diagnosis (mean 48 vs 30 years P < 005), initial mode of presentation (no PHEO detected by routine screening in NF1 vs 40% in other genetic syndromes P < 005) and familial history of catecholamine-secreting tumour (none in NF1 vs 55% in patients with other genetic syndrome P < 005). ConclusionsPheochromocytoma in NF1 occurs in older patients with no family history compared to other syndromes; it is mostly unilateral, secretory and benign. The older age at diagnosis of PHEO could be secondary to delay in identification due to lack of systematic screening for PHEO in NF1.