Endocrine Abstracts

Introduction: Peritoneal implantation of benign pheochromocytomas – also known as pheochromocytomatosis – is a rare event caused by tumour rupture during surgical intervention. In our tertiary referral centre, we managed over two hundred patients with adrenal pheochromocytoma in the past 27 years. Now we report on the two cases diagnosed and followed with pheochromocytomatosis.

Case 1: A 33-year-old man presenting with paroxysmal hypertension and palpitation was diagnosed with a left adrenal pheochromocytoma (60 mm largest diameter). Laparoscopic adrenalectomy was carried out in 2011. Difficulties manipulating the tumour required deliberate fragmentation to insert it into the entrapment bag. Hypertension and vasomotor symptoms resolved after surgery. Five years later, the patient presented with clinical and biochemical recurrence. During a second surgical exploration in 2017, multiple 2-3 mm nodules were found on the peritoneum forming a tumour-like mass in the left hypochondrium. Debulking tumorectomy with distal pancreatectomy and splenectomy were performed. Metanephrine and normetanephrine excretions remained elevated but non-progressive, 3-metoxitiramin excretion is within the reference range. On the most recent 123I-MIBG SPECT-CT, multiple radiotracer uptaking nodules were visualised on the peritoneal surfaces, around the left kidney and on the lower surface of the liver, however, distant metastases were not described. On doxazosin, the patient has rare mild symptoms of catecholamine excess, however; he is normotensive.

Case 2: A 34-year-old woman presented with hypertension, palpitation, tremor, headaches, and muscle cramps. She had elevated urinary metanephrine, and abdominal MRI showed a 46 mm pheochromocytoma in the left adrenal. Laparoscopic tumour removal was performed in 2006. Upon dissection, both the capsule and the tumour were found to be ruptured. Urinary metanephrines dropped to normal after surgery. Four years after the primary resection, a non-progressive metanephrine excretion wasdetected, while normetanephrine and 3-metoxitiramin excretions were within normal limits. The patient remained asymptomatic for the next nine years; successfully carried out a pregnancy. Repeated CT, MRI and 123I-MIBG imaging showed multiple nodules in the left adrenal bed and on the peritoneal surfaces, considered to be unresectable. Distant metastases were not visualised. Fourteen years after the primary surgery, the patient is normotensive on prazosin monotherapy.

Family history and genetic testing for hereditary pheochromocytoma/paraganglioma syndromes were negative in both cases.

Conclusions: Benign pheochromocytoma may recur because of tumour capsule rupture and local spillage of tumour cells during surgical resection, with subsequent peritoneal dissemination and implantation. Consecutive pheochromocytomatosis can account for difficult diagnostic and therapeutic challenge.