Mixed germ cell tumor of the pineal gland in a pediatric patient

Tumors of the pineal region are a rare clinical entity, comprising approximately 3%-8% of pediatric tumors. Based on their histopathological features, they are typically classified as pineal parenchymal tumors and germ cell tumors, with the latter being more prevalent. Clinical presentation is heterogeneous, with symptoms arising either due to tumor invasion or compression of adjacent neurovascular structures and increased intracranial pressure. Imaging studies are paramount in evaluating pineal region lesions and establishing an accurate diagnosis, with MRI representing the gold standard. Herein, we present the case of a 16-year-old boy presented with recurrent headaches. A head MRI revealed a pineal gland lesion. Histopathological examination confirmed the diagnosis, and the patient underwent a successful gross total resection (GTR) of the tumor. This case report seeks to draw attention to the elusive clinical presentation and management of this infrequently encountered tumor, as well as emphasize the importance of considering pineal gland tumors in the differential diagnosis of recurrent, chronic headaches in pediatric patients.     

Design and Validation of Additively Manufactured Metallic Cellular Scaffold Structures for Bone Tissue Engineering

Bone-related defects that cannot heal without significant surgical intervention represent a significant challenge in the orthopedic field. The use of implants for these critical-sized bone defects is being explored to address the limitations of autograft and allograft options. Three-dimensional cellular structures, or bone scaffolds, provide mechanical support and promote bone tissue formation by acting as a template for bone growth. Stress shielding in bones is the reduction in bone density caused by the difference in stiffness between the scaffold and the surrounding bone tissue. This study aimed to reduce the stress shielding and introduce a cellular metal structure to replace defected bone by designing and producing a numerically optimized bone scaffold with an elastic modulus of 15 GPa, which matches the human’s cortical bone modulus. Cubic cell and diagonal cell designs were explored. Strut and cell dimensions were numerically optimized to achieve the desired structural modulus. The resulting scaffold designs were produced from stainless steel using laser powder bed fusion (LPBF). Finite element analysis (FEA) models were validated through compression testing of the printed scaffold designs. The structural configuration of the scaffolds was characterized with scanning electron microscopy (SEM). Cellular struts were found to have minimal internal porosity and rough surfaces. Strut dimensions of the printed scaffolds were found to have variations with the optimized computer-aided design (CAD) models. The experimental results, as expected, were slightly less than FEA results due to structural relative density variations in the scaffolds. Failure of the structures was stretch-dominated for the cubic scaffold and bending-dominated for the diagonal scaffold. The torsional and bending stiffnesses were numerically evaluated and showed higher bending and torsional moduli for the diagonal scaffold. The study successfully contributed to minimizing stress shielding in bone tissue engineering. The study also produced an innovative metal cellular structure that can replace large bone segments anywhere in the human body.     

Redefining the R1 resection for pancreatic ductal adenocarcinoma: tumour lymph nodal burden and lymph node ratio are the only prognostic factors associated with survival

Introduction: The presence of positive nodal disease (LND) and the number of lymph nodes involved (LNB) are known to be significant prognostic markers for resected adenocarcinoma of the pancreas. In addition, the ratio of the number of involved nodes to the number of nodes resected known as the lymph node ratio (LNR) is emerging as an important prognostic marker. The role of the resection margin (RM) as presently defined (R1 ≤ 1 mm) is unclear as results differ based on the dataset. The aim of this study was to assess the impact of nodal disease and a redefined RM on outcome.Material and methods: Retrospective analysis of pancreatic head resections for adenocarcinomas from 2003–2009. The RM was re-analysed based on tumour clearance and categorized into: histopathological evidence of a tumour; ≤0.5 mm, ≤1 mm, ≤1.5 mm, or ≤2.0 mm of the actual surgical resection margin. The impact of histopathological variables on cancer-specific survival (CSS) and disease-free survival (DFS) was analysed.Results: LND, LNB and LNR were independent prognostic markers for CSS (P = 0.048, 0.003, 0.016) but, did not influence DFS. A LNR < 0.143 was associated with a higher CSS [38.16 ± 4.69 versus 20.59 ± 2.20 months, P = 0.0042, hazard ratio (HR) 3.74 (95% confidence interval (CI) 1.52–9.23)]. An R1 RM was not associated with CSS or DFS on multivariate analysis, irrespective of the distance. LNB and LNR maintained independent significance irrespective of the size of the RM.Conclusion: LNB and LNR are the only prognostic factors for CSS in patients with pancreatic head adenocarcinoma, but do not predict recurrence. Microscopic RMs does not seem to influence the outcome even when redefined. Further prospective studies are indicated to substantiate these findings.