Extra-adrenal peripheral neuroblastic tumors: A clinicopathological study of 18 cases

Background: Peripheral neuroblastic tumors arise from the sympathoadrenal lineage of the neural crest. They have been classified according to the International Neuroblastoma Pathology Committee (INPC) into Four categories according to International Neuroblastoma Pathology Committee (INPC): a) Neuroblastoma (NB) b) Ganglioneuroblastoma (GNB), nodular c) Ganglioneuroblastoma, intermixed, and d) Ganglioneuroma (GN). Because of the rarity of extra-adrenal peripheral neuroblastic tumors, limited information is available regarding the chemotherapy of NB and GNB. A few case reports or case series with a small number of patients have been documented in the literature. Aim: To describe the clinicopathological characteristics of extra-adrenal peripheral neuroblastic tumors. Materials and Methods: Clinical, histopathological, and immunohistochemistry (IHC) findings of 18 cases were retrieved. Immunohistochemistry at the time of diagnosis was performed using Ventana Benchmark XT. The mean value was calculated using the Microsoft Office Excel 2019 software. Results: The posterior mediastinum was the most commonly affected extra-adrenal site in our study. Neuroblastoma consisted of eight cases (six in children, two in adults), of which four cases were poorly differentiated and the other four cases were differentiating. Two cases had favorable histology. The bone marrow and cervical lymph node metastasis were documented. Of the four GNB cases, one patient developed bone metastasis. All patients of NB and GNB received combination chemotherapy. One out of six GN patients presented with a large retroperitoneal mass encasing the aorta and renal vessels, mimicking a sarcoma. Conclusion: Extra-adrenal peripheral neuroblastic tumors do not pose any diagnostic issue in adequate tissue sampling. In limited material, immunohistochemistry is needed. The chemotherapy regimen has not been standardized due to rarity. Further molecular testing and targeted therapy may be of help in the future.