Endocrine Abstracts

Phaeochromocytoma and paragangliomas (PH/PG) are rare neuroendocrine tumours. Prediction of aggressive tumour behaviour remains a major challenge. The Phaeochromocytoma of the Adrenal gland Scaled Score (PASS) is used to separate benign from malignant lesions with a score > 4 showing potential for biologically aggressive behaviour. Pre-operatively, MIBG together with CT/MRI remain the diagnostic radiological gold standard.

We report a 68-year-old female who was found to have a locally arising colonic adenocarcinoma on biopsies. Staging also identified a 10.7 cm right adrenal lesion and work-up revealed markedly raised urinary metanephrines and positive MIBG imaging. The MDT decision was to first remove the colonic cancer with appropriate alpha blockade. It was felt that a combined laparoscopic approach would not be appropriate given the adrenal lesion size, which might require an open procedure. Histology confirmed a stage III Duke’s C tumour and adjuvant chemotherapy commenced. Although adrenal surgery had been planned once she completed chemotherapy, she did not tolerate chemotherapy and it had to be discontinued. An open adrenalectomy was undertaken. Histology was consistent with a phaeochromocytoma with a PASS score of eight. 2 months after adrenal surgery, she reported intermittent tingling and numbness in the left arm with thoracic back pain. An MRI confirmed a soft tissue mass at T₂ extending into the spinal cord. Urinary metanephrines confirmed persistently elevated normetadrenaline levels. She underwent bilateral laminectomy under alpha-blockade. Histology confirmed a metastatic phaeochromocytoma. She is currently awaiting Ga⁶⁸-DOTATATE PET-CT imaging to guide further management.

Ga⁶⁸-DOTATATE PET-CT has been shown to be the most sensitive imaging modality for detection of metastatic PH/PG and would potentially have identified metastatic lesion(s) not seen on MIBG scanning. We therefore propose that Ga⁶⁸-DOTATATE PET-CT – where available – should be used for initial staging and MIBG should be reserved for those patients only for whom MIBG therapy is being considered.