Endocrine Abstracts

Background: The detection of phaeochromocytomas evolved from autopsy finding to presentation in symptomatic/hypertensive, and genetically-predisposed individuals. Increasingly, phaeochromocytomas are diagnosed in incidental adrenal masses and the impact on the clinical, biochemical, and radiological features is unclear.

Methods: Retrospective review of patients with phaeochromocytomas seen at a large tertiary referral centre between January 2010 and May 2022. Diagnosis was confirmed histologically or with positive combination of indeterminate adrenal mass, unambiguously increased plasma and/or urinary metanephrines/normetanephrines (MN/NMN), and MIBG findings.

Results: We identified 149 patients with phaeochromocytoma; 131 (88.0%) underwent adrenalectomy, for 18 (12.0%) surgery was either awaited, carried high operative-risk, or declined by patients. Women represented 59.1% (n=88). Median age at diagnosis was 52 years (range=12-86). After excluding phaeochromocytomas diagnosed upon screening for genetic predisposition, patients presented with: 77 of 115 (67.0%), incidental; 20 (17.4%), adrenergic symptoms (e.g., palpitations); 18 (15.7%), hypertension. Presentation with bilateral phaeochromocytomas was in 8.7% (n=13). Three patients presented with metastatic disease. Median size of phaeochromocytomas was: overall, 47 mm (range=10-215 mm); diagnosed upon screening for genetic predisposition, 30 mm (range=10-75 mm); incidental, 42 mm (range=10-180 mm); symptomatic/hypertensive patients, 56 mm (range=15-215 mm) (all P-values=<0.05). Unenhanced CT was performed pre-operatively in 71 patients, all had tumour density ≥10 Hu or tumour was heterogeneous. Median MN/NMN increase was 5-10-fold (range=normal-95-fold), which was lower in patients with incidental phaeochromocytoma compared to symptomatic/hypertensive patients (P-value=<0.001). Phaeochromocytomas diameter positively correlated with fold increase in MN/NMN (r=0.62; P-value=<0.0001). MN/NMN production increased in incidental phaeochromocytomas with size: median size ≤20 mm (n=6), median MN/NMN ≤2-fold; size >20-30 mm (n=11), 2-3-fold; >30-40 mm (n=16), 3-4-fold; >40 mm (n=43), >10-fold (all P-values=<0.05).

Conclusion: Phaeochromocytomas most presented as adrenal incidentalomas. Small incidental phaeochromocytomas modestly increase MN/NMN and may represent a diagnostic challenge. Appropriate assessment of adrenal incidentalomas is crucial to avoid the adverse consequences of unrecognised phaeochromocytomas.