Endocrine Abstracts

Background: Composite pheochromocytoma (CP) is a rare condition with only about one hundred cases reported in the medical literature. The diagnosis is based solely on pathological findings, with most patients having manifestations of excess catecholamines with no distinctive pre-operative clinical or radiological features compared to usual pheochromocytoma (PCC) or paraganglioma (PGL). Prompt and accurate diagnosis of the neural and endocrine components is vital, as undifferentiated, or poorly differentiated tumours have prognostic implications if malignancy affects one or both components of the composite tumour.

Case report: A 43-year-old normotensive male was referred for evaluation of an incidentally detected heterogeneous left adrenal mass (46mm x 31mm x 29mm). The patient described adrenergic symptoms that included excessive sweating, anxiety, and headaches. Plasma metanephrine and normetanephrine levels were elevated (518 pmol/l and 3670 pmol/l respectively). MIBG Iodine 123 SPECT Scan showed marked focal tracer uptake within the left adrenal gland consistent with a phaeochromocytoma. Laparoscopic left adrenalectomy was undertaken after appropriate pre-operative alpha and beta blockade. Histology of the excised adrenal tumour showed composite pheochromocytoma, with a ganglioneuroma as the histological second component. On immunohistochemistry staining, both tumours stained positive for chromogranin and synaptophysin. The ganglioneuroma tissue component was highlighted by neurofilament, S100 and SOX-10 positivity. Plasma metanephrines normalised after surgery.

Discussion: While pheochromocytoma and paragangliomas are tumours that originate from the chromaffin cells, ganglioneuroma represents the mature spectrum of tumours from autonomic ganglion cells or their precursors. The vast majority of composite pheochromocytoma with ganglioneuroma are benign with malignant pheochromocytoma reported in about 3% of cases. Approximately 13% of composite pheochromocytoma/-ganglioneuromas are known to metastasise. Long term follow-up is vital to monitor for risk of recurrence and metastases.