Metastatic Somatostatinoma: A rare cause of diabetes requiring insulin therapy
R Sussman, R W Carroll, A Ghaffar, K Meeran, J F Todd
Imperial Centre for Endocrinology.
BW, a 49 year old school nurse, was referred to the endocrinology clinic with a recent diagnosis of metastatic neuroendocrine tumour. She had a long history of numerous symptoms including a 15-20 year history of right sided lower chest and upper abdomen pain which had worsened in the preceding months, and had recently developed flushing, indigestion, and increased defecation. Ultrasonography revealed liver and renal masses and she was referred for subsequent assessment.
The following investigations were performed:
Three sets of 24 hour urine 5HIAA and the urinary catecholamine’s were normal. Gut peptides showed raised chromogranin B GAWK fragmen (351, 165pmol/L). Somatostatin levels were initially normal. Concurrent primary hypothyroidism documented with TSH=15.1mU/L, FT3 4.4 pmol/L, and FT4 10.2 pmol/L and levothyroxine was commenced CT revealed a 5.2cm mass in the right kidney and a 15x12.6cm hepatic mass. Both lesions were avid on octreotide scanning. Biopsy of the renal mass revealed histology consistent with neuroendocrine tumour (NET). A MAG-3 renal scan attributed 40% of renal function to the affected kidney. Radiologically guided hepatic biopsy was consistent with metastatic NET.
Follow up at 1 year revealed an increase in the size of the renal and liver lesion, with a further liver lesion and possible splenic lesion noted. Serum somatostatin was noted to be significantly elevated (>1000pmol/L) and coincided with the development of diabetes requiring insulin treatment, and steatorrhoea. Following discussion with the Endocrinology MDT, Octreotide therapy was offered but declined. Embolization of the large hepatic lesion was performed with the post procedure phase complicated by pneumonia.
Somatostatinomas are rare and nearly always pancreatic or duodenal in origin. We describe a case of metastatic disease with a possible renal primary and a ‘somatostatin’ syndrome, and discuss management of this rare presentation. Initial normal somatostatin levels followed by significantly raised levels suggests tumour de-differentiation. Following hepatic embolization, glycaemic control has improved significantly allowing the removal of insulin therapy.