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Pancreatic neuroendocrine tumors in von Hippel–Lindau disease

Dear Editor, TY Park et al. recently reported a retrospective series of 55 patients with von Hippel–Lindau (VHL) disease and pancreatic involvement [1]. Since VHL disease is a rare genetic condition, this fairly large series might be of valuable information. However, we are quite surprised by the patient selection. Particularly, we do not know the reason why so many patients were excluded from the “VHL population”: the gold standard is genetic testing and only half of the patients had molecular confirmation of the diagnosis. Pancreatic involvement is frequent in VHL disease, including pancreatic cysts, serous cystadenomas and pancreatic neuroendocrine tumors (PNETs) [2]. Among them, PNETs are the major (if not exclusive) concern, because of the significant risk of metastatic course, thus warranting surgical resection or rigorous observation. Hence, it is of major importance to firmly assess the diagnosis of PNETs. Notably, the diagnosis criteria used by Park et al. (i.e. hypervascular mass strongly enhancing on computed tomography scan during arterial phase) is surprising and not validated [1]. Particularly, such criteria may not allow for accurate differentiation between PNET and metastasis from renal cell carcinoma or, more frequently, a pseudo-solid form of microcystic serous adenoma [3]. In a series, the latter accounted for the final pathological diagnosis of 15% of pancreatic surgical resections performed for presumed PNET [4]. Hence, diagnosis inaccuracy could explain the unusual rate (32.7%, twofold higher than that in the literature) of patients with PNET in the study by Park et al. [1]. Obtaining positive somatostatin-receptor scintigraphy and/or pathological confirmation is the optimal way to assess a firm diagnosis of PNET [5]. Management of VHL-related PNET is challenging, not only due to their frequent multiplicity but also due to simultaneous other life-threatening organs involvement (renal cancer, hemangioblastoma, and pheochromocytoma). Efforts have been made over the past decades to define the PNET patients requiring surgery, as reported by Libutti et al. [6], with the aim of a parenchyma-sparing strategy. In addition, we have recently reported that removing only the deemed