Reduced uptake pattern on 68 Ga-DOTATATE-scan may indicate necrosis predicting aggressive behavior in pheochromocytoma and paragangliomas (PPGLs).

Abstract

Predicting malignancy among pheochromocytoma paragangliomas (PPGLs) remains a challenge, with only limited understanding of the clinical and molecular characteristics. It has been suggested that reduced avidity of a PPGL on 68 Ga-DOTATATE PET/CT could be a sign of not only altered metabolic activity, but also of increased biologic aggressiveness, possibly due to loss of SSTR-expression. Retrospective cohort review. Thirty-seven patients who underwent treatment for PPGL at a tertiary institution over the period 2010-2022, had their biochemical, radiological, and clinicopathological variables collected. Five of 37 (13%) patients (5 males) with a mean age of 42 years were found to have malignant PPGLs. The mean size of the tumors were 5.4 cm, with 4 located in the paraaortic area and 1 in right adrenal. Functional imaging with 68 Ga-DOTATATE PET/CT showed a mean SUVmax of 4.5. Four of 5patients underwent open resection of the tumors under general anesthesia following preoperative alpha blockade with oral phenoxybenzamine. The mean PASS score of the excised tumors was 5.5 in keeping with biologically aggressive tumors, with evidence of necrosis. All but 1 patient had germline SDHB-mutation (Deletion Exon 1). Postintervention after a mean follow-up of 31 months, 2 of 5 (40%) patient developed spinal metastasis and 1 patients (25%) died of cardiac complications. A non-highly avid PPGL on DOTATE scan should be considered as possibly having necrosis of tumors indicating a more aggressive tumor-biology. There might be a subgroup of patients in whom FDG-PET scan should be considered to gain additional information.