Recurrent polytopic chromaffin paragangliomas in a 9-year-old boy resulting from a novel germline mutation in the von Hippel-Lindau gene

Pediatric Neuroendocrine Neoplasms: Rare Malignancies with Incredible Variability

Neuroendocrine neoplasms (NENs) encompass a variety of neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs) which can arise anywhere in the body. While relatively rare in the pediatric population, the incidence of NENs has increased in the past few decades. These neoplasms can be devastating if not diagnosed and treated early, however, symptoms are variable and can be indolent for many years. There is a reported median of 10 years from the appearance of the first symptoms to time of diagnosis. Considering some of these neoplasms have a mortality rate as high as 90%, it is crucial healthcare providers are aware of NENs and remain vigilant. With better provider education and easily accessible resources for information about these neoplasms, awareness can be improved leading to earlier disease recognition and diagnosis. This manuscript aims to provide an overview of both the most common NENs as well as the rarer NENs with high lethality in the pediatric population. This review provides up to date evidence and recommendations, encompassing recent changes in classification and advances in treatment modalities, including recently completed and ongoing clinical trials.

VHL disease

von Hippel-Lindau disease (VHL) disease increases susceptibility to several malignancies, including renal cell carcinoma, haemangioblastomas of the central nervous system or retina and phaeochromocytomas. The VHL tumour suppressor gene, responsible for the disease, encodes for a major regulator of the hypoxic response by targeting the transcription factor hypoxia inducible factor (HIF) for degradation. In this review, we present a synopsis of clinical features of the disease and emphasise unique aspects of VHL syndrome in the paediatric population. Genotype-phenotype associations based on the risk of phaeochromocytoma have pointed to the existence of additional, HIF-independent functions of VHL that remain underexplored. We also examine the progress on these pleiotropic roles of VHL, which contribute to explain clinical features of VHL disease. These advances have important translational implications and are likely to offer a new host of therapeutic options to individuals affected by the disease in the future.

Emergencies caused by pheochromocytoma, neuroblastoma, or ganglioneuroma

Pheochromocytoma may lead to important emergency situations, ranging from cardiovascular emergencies to acute abdomen and multiorgan failure. It is vital to think about this disease in any emergency situation when conventional therapy fails to achieve control or symptoms occur that do not fit the initial diagnosis. The importance of keeping this diagnosis in minds is underscored by the fact that, in 50% of pheochromocytoma patients, the diagnosis is initially overlooked. Two other tumors of the sympathetic nervous system, neuroblastoma and ganglioneuroma, are less commonly associated with emergency conditions. If they occur, they are often linked to catecholamine excess, paraneoplastic phenomena, or local tumor mass effect.

Laparoscopic and retroperitoneoscopic treatment of pheochromocytomas and retroperitoneal paragangliomas: results of 161 tumors in 126 patients

BACKGROUND

Laparoscopic and retroperitoneoscopic excisions of pheochromocytomas and retroperitoneal paragangliomas are challenging surgical procedures because of extensive intraoperative catecholamine release, extreme vascularization, and demanding localization.

MATERIALS

In a prospective clinical study 161 chromaffine neoplasias (134 pheochromocytomas, 27 paragangliomas) were removed endoscopically in 126 patients (67 males, 59 females, age 41.7 +/- 16.4 years; 130 operations). Six patients showed multiple (2-5) tumors. Tumor size ranged from 0.5 to 12 cm (mean 3.5 +/- 1.9 cm). Forty-two patients suffered from hereditary diseases. Twenty-four patients had bilateral adrenal diseases; in 14 patients pheochromocytomas were removed on both sides synchroneously. Ten neoplasias were local or loco-regional recurrences (7 pheochromocytomas, 3 paragangliomas). The laparoscopic route was chosen in 16 operations; the retroperitoneoscopic technique was performed in 128 others. Partial adrenalectomies were performed in 57 operations (in all but one of the patients with bilateral disease). High-dosage alpha-blockade with phenoxybenzamine was routinely used.

RESULTS AND DISCUSSION

Conversion to open surgery occurred once. Perioperative complications were minor (17%); mortality was zero. Operating time for unilateral retroperitoneoscopically removed primary pheochromocytomas (n = 113) was 82 +/- 49 minutes (range: 20-300 minutes) and depended on tumor size (< 3 cm vs. > or = 3 cm; P < 0.05) and gender (P < 0.001), but not on extent of resection (partial vs. total, P = 0.266). Operating time for paragangliomas ranged from 55 to 600 minutes. Median blood loss was 20 ml. Median duration of postoperative hospitalization was 4 days. In 22 of 24 patients with bilateral disease, complete preservation of cortical function was achieved. Locoregional and/or distant metastatic recurrence were found in 5 patients.

CONCLUSIONS

Endoscopic removal of solitary, bilateral, multiple, and recurrent pheochromocytomas and retroperitoneal paragangliomas is feasible and safe, but surgeons need extensive experience in minimally invasive techniques, as well as in endocrine surgery.

Regulation of microtubule stability by the von Hippel-Lindau tumour suppressor protein pVHL

Von Hippel-Lindau (VHL) tumour suppressor gene inactivation is linked to the development of haemangioblastomas in the central nervous system and retina, often in association with other tumours, such as clear-cell carcinomas of the kidney and phaeochromocytomas. Here we show that the VHL protein (pVHL) is a microtubule-associated protein that can protect microtubules from depolymerization in vivo. Both the microtubule binding and stabilization functions of pVHL depend on amino acids 95-123 of pVHL, a mutational 'hot-spot' in VHL disease. From analysis of naturally occurring pVHL mutants, it seems that only point mutations such as pVHL(Y98H) and pVHL(Y112H) (that predispose to haemangioblastoma and phaeochromocytoma, but not to renal cell carcinoma) disrupt pVHL's microtubule-stabilizing function. Our data identify a role for pVHL in the regulation of microtubule dynamics and potentially provide a link between this function of pVHL and the pathogenesis of haemangioblastoma and phaeochromocytoma in the context of VHL disease.