Bilateral phaeochromocytoma in neurofibromatosis type 1 - a rare entity but not to be missed

Amalka Premadasa; Yuvanaa Subramaniam; Hubbard Jonathan G; Anand Velusamy; Paul Carroll

doi:10.1530/endoabs.109.P34

P34

Prev Next

Section Contents Cite

Endocrine Abstracts (2025) 109 P34 | DOI: 10.1530/endoabs.109.P34

SFEBES2025 Poster Presentations Adrenal and Cardiovascular (61 abstracts)

Bilateral phaeochromocytoma in neurofibromatosis type 1 - a rare entity but not to be missed

Amalka Premadasa , Yuvanaa Subramaniam , Jonathan G Hubbard , Anand Velusamy & Paul Carroll

Author affiliations

Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom

We present a 65-year-old gentleman with Neurofibromatosis Type 1 (NF-1), referred for assessment of adrenal nodularity. These were incidental findings on CT as he had imaging for obstructive defaecation and weight loss. Colonoscopy showed a proximal ascending colon lesion with histology keeping with inflammatory polyp. There were no clinical features indicative of catecholamine excess. The MDM considered carefully the comprehensive imaging. Although there was confidence that the right lesion was phaeochromocytoma, on balance bilateral adrenalectomy was recommended given the indeterminate nature of the left gland, with underlying NF-1.

Histology revealed bilateral pheochromocytoma:

Right nodule - Ki67 2.4%, PASS 9/20

Left nodule - Ki67 0.7%, PASS 3/20

Table 1. Performance of the best ML models
Biochemistry	Results (pmol/l)	Normal values (pmol/l)
Plasma metadrenaline	9;2,546	<510
Plasma normetadrenaline	1,800	<1180
Plasma 3-methoxytyramine	73	<180
Imaging
CT Adrenals	2 cm right adrenal nodule with small cystic spaces: -Pre-contrast attenuation of 42HU -Absolute washout 55% -Relative washout 31% -Small cystic spaces shows persistent enhancement 1.7 cm left medial limb nodule: -Benign washout characteristics 1.1 cm left proximal medial limb nodule: -Pre-contrast attenuation of 32HU -Absolute washout 32% -Relative washout 19%
MR Adrenals	2 cm well-circumscribed right adrenal body, suspicious for phaeochromocytoma Indeterminate left adrenal lesions, T2 hyperintensity
MIBG Iodine 123 scan	Pathological high-grade increased uptake in right adrenal mass lesion No pathological activity in left adrenal gland
FDG-PET CT	High-grade uptake caecal mass Moderate uptake in right adrenal nodule consistent with a pheochromocytoma Low-intensity update in 1.1 cm left nodule

Post-operative plasma metanephrines were unremarkable. Subsequently, he underwent an open right hemicolectomy and ileocolostomy. There were 56 polyps, but none were suggestive of moderate/high grade dysplasia. The genetic susceptibility and association between NF-1 and pheochromocytoma is known with incidence of 0.1-5.7%. Bilateral pheochromocytoma is even rarer. Screening for phaeochromocytoma should be considered in these patients with careful decision making, especially when bilateral adrenal lesions are present.