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In response to ‘Pancreatic neuroendocrine tumors in von Hippel–Lindau disease’, by Louis de Mestier & Pascal Hammel

Dear Editor, We appreciate the comments from de Mestier L and colleagues and agree with their opinion about our study. von Hippel–Lindau (VHL) disease is a rare genetic disorder and has been given the diagnostic code Q858 according to the International Classification of Diseases 10 in our center. Diagnostic code Q858 of International Classification of Diseases 10 has been used to describe other phakomatoses, not elsewhere classified disease. Therefore, it was assumed that there might be considerable other rare disease given diagnostic code Q858 other than the VHL disease. This was the reason why many patients who did not meet clinical diagnostic criteria for VHL disease were considered to be not eligible and excluded from the ‘VHL population’ [1]. Molecular confirmation of mutation in the VHL gene is gold standard for the diagnosis of VHL disease. Since the VHL tumor suppressor gene was first isolated in 1993, advances in genetic testing, including multiple ligation-dependent probe amplification analysis, have increased the detection rate of VHL gene mutation to approximately 80–100% [2,3]. However, genetic testing is expensive and not covered by public or private health insurance in Korea. Furthermore, considering the sentiments of Koreans, most of the clinically suspicious VHL patients, even in case of affected family, are reluctant to undergo genetic testing; some of them considered this genetically inherited condition to be unacceptable and refused to undergo genetic testing. Therefore, practically, it is not easy to perform genetic testing in all clinically suspicious VHL patients [1]. Contrast-enhanced CT scan is a sensitive and easily available method for detecting pancreatic neuroendocrine tumor (NET) in VHL patients [4,5]. However, enhancing pancreatic mass on CT scan in VHL patients can be metastatic renal cell carcinoma, adenocarcinoma, NET and solid microcystic serous adenoma. Solid microcystic serous adenomas are hypervascular and solid-looking and are often misdiagnosed as NET on imaging study [6]. Therefore, particular attention should be paid for distinguishing pancreatic NETs that would require surgery from solid microcystic serous adenomas and unnecessary pancreatic surgery, which is associated with morbidity and mortality, should be avoided. Somatostatinreceptor scintigraphy, which is not available in Korea, can be helpful, and pathologic work-up should be considered. Pancreatic NETs in VHL disease are more likely to be detected at a relatively early stage and young age by screening examination compared with sporadic nonfunctioning pancreatic NET [7]. This point could be associated with favorable prognosis of pancreatic NETs in VHL disease compared with that of sporadic non-functioning pancreatic NET. Although several studies have suggested management strategy for VHL-associated pancreatic NET, there has been no consensus [8–10]. Surgical resection of VHLassociated pancreatic NET should be decided with caution considering size, location, number of lesions, comorbidity and compliance of VHL patients.