Cystic Pheochromocytomas Show Distinct Biochemical and Radiological Features, Indian Study Finds

While earlier series by Erickson and colleagues and Mayo Clinic researchers documented rare cystic adrenal neoplasms, limited literature on specific bio-radiological traits has created a clinical gap that risks misdiagnosis as simple cysts and unsafe aspirations. Addressing this issue, Somdatta Giri and co-investigators from the Department of Endocrinology at Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India, conducted a comparative study evaluating clinical, biochemical, radiological, and intraoperative parameters between cystic and non-cystic pheochromocytomas.

Therefore, the 10-year retrospective study at JIPMER compared 46 patients with confirmed pheochromocytoma—8 predominantly cystic and 38 non-cystic—excluding those with incomplete records. Investigators analyzed clinical features, plasma metanephrine levels, CT imaging metrics, and intraoperative hemodynamics across both patient groups.

Key Clinical Findings of the Study Includes:

• Reduced Catecholamine Secretion: Investigators found that patients with cystic pheochromocytomas had a significantly lower prevalence of elevated plasma normetanephrine levels than non-cystic cases (37.5% vs. 85.7%, P = 0.005), with zero adrenergic-secreting tumors in the cystic group versus 31% in non-cystic tumors.

• Left-Sided Predominance: Researchers observed a strong lateralization preference, with cystic tumors occurring significantly more often in the left adrenal gland than non-cystic lesions (85.7% vs. 29.4%, P = 0.005).

• Lower Baseline CT Attenuation: Authors demonstrated that cystic tumors displayed significantly lower unenhanced baseline CT attenuation values compared to non-cystic counterparts (31.3 ± 8.2 HU vs. 39.25 ± 7.6 HU, P = 0.033), with 37.5% exhibiting the hyper-enhancing "ring sign".

• Larger Volume and Mass Effect: The study revealed that cystic lesions presented with larger mean diameters (7.2 ± 3.4 cm vs. 5.8 ± 2.6 cm, P = 0.31) and total volumes (105.1 ± 75.5 cm³ vs. 48.5 ± 33.8 cm³), driving mass effect symptoms in 42.9% of cases.

• Attenuated Hemodynamic Instability: Data showed that cystic pheochromocytoma patients experienced fewer intraoperative hypertensive spikes (systolic blood pressure [SBP] ≥160 mmHg; median 0 vs. 2 episodes, P = 0.11) and lower maximum SBP peaks (150 mmHg vs. 170 mmHg, P = 0.19) than non-cystic patients.

The results suggest that predominantly cystic pheochromocytomas represent a distinct neuroendocrine entity defined by lower biochemical secretory activity (37.5% normetanephrine elevation), left-sided anatomical localization (85.7%), larger volume (105.1 cm³), and lower baseline attenuation (31.3 HU). Consequently, clinicians must integrate multimodality imaging rather than relying solely on screening catecholamines to avoid missing cystic adrenal lesions.

Thus, the study concludes clinicians should maintain a high index of diagnostic suspicion and utilize comprehensive cross-sectional imaging alongside functional scans when evaluating biochemically negative or atypical adrenal cystic masses prior to invasive procedures.

While the retrospective single-center design, small cystic cohort, single-radiologist review, and radiological volume assessment present minor constraints, prospective multicentric studies with larger clinical cohorts would further validate these bio-radiological observations.

Reference

Giri S, Prasad A, Kumari B, Sreerag KS, Kalra S, Ramkumar G, et al. Comparison of the clinical and biochemical parameters between cystic and non-cystic pheochromocytoma. Indian J Endocr Metab 2026;30:346-51.