Renal cell carcinoma presenting as a pseudo-carcinoid tumour

A 38-year-old woman presented with hypertension and a renal cell carcinoma. Raised urinary 5-hydroxyindoleacetic acid values >300 micromol/l, predictive of carcinoid tumour, were found during the perioperative period. The values returned towards normal 2 weeks post-surgery. Immunohistochemical examination of the renal cell carcinoma with neuroendocrine markers was negative. Despite a diligent search, no carcinoid tumour could be identified and the patient was well 4 years later. There was no dietary or drug explanation for this pseudocarcinoid.