Neurogenic tumors of the mediastinum

Abstract

Mediastinal lesions are rare and usually of neurogenic origin, predominantly located in the posterior mediastinum. Their specific locations are typically the paravertebral sulci. The most common types of lesions are thymomas (27.8%), benign mediastinal cysts (20.0%), and lymphomas (16.1%). The distribution of lesions varies among mediastinal compartments, with thymomas (38.3%), benign cysts (16.8%), and neurogenic tumors (53.9%) being the most common in the prevascular, visceral, and paravertebral mediastinum, respectively. The relative frequency of different cell types and their malignancy risk are strongly associated with age. Children and young individuals mostly have tumors originating from autonomic ganglia, two-thirds of which are malignant. In adults, tumors originating from nerve sheaths are more common and mostly benign. These lesions also vary across continents or countries; benign cysts are the most common mediastinal lesions in the People's Republic of China, thymomas in Europe, and lymphomas in North America and Israel. Benign cysts, thymic carcinomas, and metastases are more frequently seen in larger hospitals, while lymphomas and thymic hyperplasia are more common in smaller hospitals. Among malignant mediastinal masses in children, lymphoma is the most common diagnosis (66.0%), followed by neuroblastoma (10.7%), germ cell tumors (5.4%), and T-cell acute lymphoblastic leukemia (17.9%). The rate of admission to the intensive care unit (ICU) can be 37.5%. Factors significantly associated with ICU admission are stridor, pericardial effusion, and the need for pleural drainage. Almost all patients (98.2%) present with symptoms, with lymphadenopathy being the most common (69.6%). Neurogenic tumors are relatively common among mediastinal masses. The distribution of diagnoses is as follows: neurogenic tumors (52%), thymic tumors (20%), teratomas (14%), and lymphomas (14%). In the cystic group, bronchogenic cysts account for 66%, pericardial cysts for 17%, and hydatid cysts for 7%. Neurogenic tumors can arise from neural elements anywhere in the thorax, including nerve sheaths, autonomic ganglia, and paraganglionic tissues. They all have an embryonic heritage derived from the neural crest. These tumors can exhibit various cytological products and immunohistochemical markers that aid in pathological diagnosis. Spinal cord invasion by the tumor occurs in approximately 10% of cases. It can be asymptomatic and incidentally discovered. The absence of a capsule, low degree of atypia, low mitotic index, and low cell density have been correlated with a lower malignancy potential. Surgical resection is the main treatment method, with an average survival estimated at 51.3 months. There is a significant difference in survival between be- nign and malignant tumors based on histological subtypes. In infants and children, these tumors usually originate from autonomic ganglion tissues and rarely from nerve sheaths. However, in adults, nerve sheath tumors derived from embryonic neural crest cells (e.g., schwannomas) are more common than those from autonomic ganglia. These neurogenic tumors exhibit varying degrees of maturation and a diversity of generated cell types. A relatively simple but comprehensive classification has been proposed for tumors seen in both infants and adults. In infants and adults, 50% to 75% of posterior mediastinal neoplasms are neurogenic, while lymphomas are more commonly found in the posterior compartment in older children. Approximately 50% to 60% of these are malignant, with the majority of mediastinal masses in children being malignant. Neurogenic tumors account for about half of all mediastinal lesions, with a prevalence of 53.9%. Among 3308 patients, thymomas (27.8%), benign mediastinal cysts (20.0%), and lymphomas (16.1%) were the most common. The distribution of lesions varies among mediastinal compartments. © 2021 Akademisyen Kitabevi A.Ş. All rights reserved.