Appendiceal neuroendocrine neoplasms and resection of the mesoappendix: a retrospective comparative study.

PURPOSE: Incidental appendiceal neoplasms are identified in approximately 1% of the specimens of suspected appendicitis. The current institutional policy is to perform en bloc mesoappendix resection during routine laparoscopic appendicectomy allowing for staging, reducing the need for oncological right hemicolectomy (ORH). Herein, we review en bloc mesoappendicectomy in clinical practice and its effects on the rate of ORH. METHODS: We reviewed all cases of appendicectomy performed at the Auckland City Hospital between 1 May 2014 and 31 May 2019. Clinical notes and histopathological reports were reviewed. All neoplasms, surgical techniques and the need for further surgery were analysed. RESULTS: A total of 2455 appendicectomies were performed with an approximately similar number of procedures between the sexes and an overall median age of 31 years. Overall, 86% (n = 2098) of the specimens included resection of the mesoappendix, and 58 (2.4%) appendiceal neoplasms were identified. Of them, 33 (1.3%) specimens included neuroendocrine appendiceal neoplasms. Eleven (33%) patients with appendiceal neuroendocrine neoplasms were recommended ORH. One of these patients may have avoided additional surgery, whereas 3 (9.1%) patients with tumours of 10-20 mm avoided ORH because their mesoappendix was resected. CONCLUSION: At our centre, there has been a significant change in the practice of mesoappendix resection, and we support resection of the mesoappendix during appendicectomy. The procedure is technically straightforward and safe, incurs no increases in costs or time, allows for accurate tumour staging and guides decisions regarding further surgical interventions.

Extragastrointestinal stromal tumour of the transverse mesocolon mimicking giant ovarian cystic neoplasm.

Gastrointestinal stromal tumours (GISTs) are mesenchymal tumours which are most commonly found along the gastrointestinal tract. They are more rarely found in an extragastrointestinal location and typically present late due to only vague symptoms from mass effect. There are very few case reports of GIST arising within the transverse mesocolon. We report a case of a large cystic transverse mesocolic GIST which preoperative imaging concluded was likely of ovarian origin. This resulted in an abrupt change in the surgical management intraoperatively, but fortunately, an R0 resection was still achieved. This serves as an important lesson to keep the differential diagnosis broad when dealing with large cystic abdominal masses. The tumour was found to be KIT wild type, with a platelet-derived growth factor receptor alpha D842V mutation identified, conferring intrinsic resistance to imatinib.