3 DISCUSSION
VIPoma in adults is primarily pancreatic tumor, with the tail of the pancreas being the most common site of origin [9]. The majority of VIPomas in pediatric patients are ganglioneuroblastomas or ganglioneuromas originating in the adrenal medulla or sympathetic neural crest, in contrast to adult cases [10]. In our institution, VIPoma has been found in only 3 patients (2.7%) among 111 with neuroblastic tumors. Among our patients with neuroblastic tumors, minimal invasive surgery (MIS) was performed in about 12.0% of cases, so MIS for VIPNT seems to be an extremely rare application.
VIPNT is divided into cases preceded by diarrhea (primary type) and cases becoming clinically evident after chemotherapy [11]. Whether neoadjuvant chemotherapy or surgery should be prioritized for patients with VIPNT and IDRF positivity or metastases has been controversial. In such cases, tumor resection after a biopsy to confirm the tumor biology and neoadjuvant chemotherapy is recommended. However, as in our case, the effects of somatostatin analogs on VIPNT may be limited [12,13]. Kabalan et al. reported the efficacy of debulking and steroids for symptoms in cases of primary type with unresectable VIPNT [13]. Their case was preceded by two courses of neoadjuvant chemotherapy, but the diarrhea symptoms did not improve. Control of VIPNT symptoms may be difficult with chemotherapy or medical treatment [11]. A surgical approach was the first-line treatment in our case to control diarrhea. While extirpation of the VIPNT should be the first choice, volume reduction might be a suitable second choice in unresectable cases with positive IDRF or amplified MYCN following chemotherapy.
MIS for VIPoma has mainly been reported in cases of pancreatic neoplasms in adult patients [14]. Pediatric patients with solid tumors may also enjoy certain benefits of MIS in terms of a faster recovery, less pain, better cosmetic results, and earlier start of adjuvant treatment [5]. The primary type of VIPNT has a favorable prognosis of 90% [11] and may be suitable for MIS among pediatric patients. The International Pediatric Endosurgery Group (IPEG) issued guidelines in 2010 for laparoscopic adrenalectomy based on level III evidence and confirmed its feasibility without absolute contraindications [15].
The most important factor to consider for MIS is the tumor size. The IPEG-issued guidelines recommend a maximum size of 6 cm in their criteria [15]. Our case had a maximum diameter of approximately 4 cm, so complete tumor excision by laparoscopic surgery was considered feasible. In addition, the preoperative evaluation of IDRF is also important for performing laparoscopic surgery [16]. The risk of open conversion should be considered preoperatively, as radiological findings may not be compatible with the intraoperative findings [4]. Our case was a feasible indication for laparoscopic surgery with a tumor size of 4 cm and negative IDRF.