Endocrine Abstracts

Introduction: The widespread use of abdominal computed tomography and magnetic resonance imaging has led to a rise in the diagnosis of incidental adrenal lesions, some of them are pheochromocytomas (Pheo).

Objective: To investigate the differences between incidental (IPheo) and symptomatic Pheo (SPheo).

Methods: A multicenter retrospective study on clinical and pathological characteristics, treatment and outcome in patients with Pheo followed up in neuroendocrinology units who underwent surgery between 1981 and 2016 was performed. The diagnosis of IPHeo was established when the adrenal lesion was discovered on a previous imaging study performed for an unrelated reason.

Results: Seventy-two patients with Pheo [44 SPheo (61%) and 28 IPheo (39%)] were studied. Age at diagnosis was significantly higher in IPheo than in SPheo patients [mean age 57±13 year vs 49±14 year; P=0.018]. There were no significant differences in sex distribution.The tumor was sporadic in 86% (n=24) of IPheo and in 80% (n=35) of SPheo (NS). The prevalence of hypertension at diagnosis was similar in both groups of patients [10 (35.7%) IPheo and in 18 (40.9%) SPheo, NS]. The 24-hour urinary fractionated metanephrines were less frequently elevated in IPheo than in SPheo patients (31% vs 70%, P=0.024). The elevation of 24-hour urinary catecholamines excretion was similar in both groups (78% vs 70%, NS). One patient (3.6%) had normal urinary catecholamines and metanephrines in IPheo group vs 3 (7.6%) in SPheo (NS). Complications during surgery were similar in both groups (15% in IPheo vs 29% in SPheo, NS). The tumor size was significantly lower in IPheo than in SPheo [4.9±2.3 cm (range, 1.5–10) vs 6.4±2.9 cm (range, 2.4–13), P=0.037]. There were no differences in both capsular and vascular invasion [5 (19%) IPHeo vs 7 (18%) SPheo, NS], as well as in the presence of necrosis [6 (24%) IPHeo vs 7 (19%) SPheo, NS], and recurrence rate between both groups. No patient had metastasic or persistant disease in IPheo group while 3 patients (6.8%) showed it in SPheo. One patient (3.6%) had recurrent disease in IPheo group vs 6 (13.6%) in SPheo (NS).

Conclusion: In our series IPheo affect older people and are smaller than SPheo. Urinary metanephrine are less frequently elevated in IPheo than in SPheo. Any incidental adrenal mass should be investigated for possible pheochromocytoma despite the absence of symptoms. Lastly, a normal hormonal study does not completely rule out the presence of a Pheo.