Anatomical study of the thoracic duct and its clinical implications in thoracic and pediatric surgery, a 70 cases cadaveric study.

INTRODUCTION: Given the high variability and fragility of the thoracic duct, good knowledge of its anatomy is essential for its repair or to prevent iatrogenic postoperative chylothorax. The objective of this study was to define a site where the thoracic duct is consistently found for its ligation. The second objective was to define an anatomically safe surgical pathway to prevent iatrogenic chylothorax in surgery for aortic arch anomalies with vascular ring, through better knowledge of the anatomical relationships of the thoracic duct. METHODS: Seventy adult formalin-fixed cadavers were dissected. The anatomical relationships of the thoracic duct were reported at the postero-inferior mediastinum, at levels T3 and T4. RESULTS: The thoracic duct was consistently situated between the left anterolateral border of the azygos vein and the right border of the aorta between levels T9 and T10, whether it was simple, double, or plexiform. It was located medially, anteromedially, or posteriorly to the left subclavian artery in 51%, 21%, and 28% of the cases, respectively, at the level of T3. At T4, it was posteromedial in 27% of the cases or had no direct relationship with the aortic arch. CONCLUSION: These results favor mass ligation of the thoracic duct at levels T9-T10 between the right border of the aorta and the azygos vein, eventually including the latter. To prevent iatrogenic postoperative chylothorax in aortic arch anomalies with vascular ring surgery, we recommend remaining strictly lateral to the left subclavian artery at the level of T3 to reach the aortic arch anomalies with vascular ring at T4.

Pediatric pheochromocytoma in association with Von Hippel-Lindau disease: Focus on screening strategies.

INTRODUCTION: Von Hippel-Lindau disease (VHL) is a syndrome of familial predisposition to the development of malignant and benign tumours, due to mutations in the VHL tumour suppressor gene. Pheochromocytoma is a tumour that develops in the adrenal gland, rare in pediatric age, and may be associated with genetic abnormalities including mutations in the VHL gene. Systematic screening of pheochromocytoma in children carrying a VHL mutation has been proposed. However, some VHL patients who have been screened may develop symptoms associated with pheochromocytoma despite screening. Here, we report on such a case. CLINICAL CASE: A 13-year-old boy, known to be a carrier of a mutation of the VHL gene, undergoing annual screening, was admitted to our hospital for clinical symptoms related to a right adrenal pheochromocytoma discovered on abdominal imaging. After hemodynamic stabilisation, the pheochromocytoma was surgically resected. Histology confirmed the diagnosis of pheochromocytoma. The postoperative care was simple. The event-free period is currently 2 years. DISCUSSION: The present case has led us to reflect on the French and international screening strategies for pheochromocytoma in children carrying a mutation of the VHL gene. Between 2013 and 2018, six different recommendations were proposed for pheochromocytoma screening in secondary prevention for children with a VHL mutation, with variability regarding the age of onset and complementary examinations to be carried out. Despite the existence of these recommendations, our case demonstrates that a pheochromocytoma can develop by escaping well-performed screening. The role of early abdominal imaging should be redefined to improve the efficiency of screening. CONCLUSION: The discovery of a pheochromocytoma in a child must be systematically investigated for an underlying genetic cause. In the particular case of children carrying a mutation of the VHL gene, annual abdominal imaging should be included in the pheochromocytoma screening protocol from the age of 5 years.