Pediatric mediastinal lymphoma

The mediastinum is the visceral compartment of thoracic cavity divided into the superior and inferior mediastinum, further inferior compartmentalize into anterior, middle, and posterior mediastinum. Lymphoma in the mediastinum may be primary or secondary to systemic disease. Lymphoma may arise from lymphoid organs-like thymus, mediastinal lymph nodes or other mediastinal organs like heart, lung, pleura, and pericardium. It comprises about 12% of all the mediastinal tumors in adults however, it constitutes 50% of the pediatric mediastinal mass. Anatomically lymphoma most commonly involves anterior mediastinum. Among the pediatric mediastinal lymphomas, lymphoblastic lymphoma (LBL) predominate followed by Hodgkin lymphoma (HL), primary mediastinal large B cell lymphoma (PMBCL) and very rarely Grey zone lymphoma. Other types of non-HLs (NHLs) are rare among pediatric population. Radiologically and clinically present as an anterior mediastinal mass with symptoms of dyspnea, cough, and superior vena cava syndrome. Also, clinically and radiologically all the pediatric mediastinal mass shares the overlapping features, hence, for treatment and prognostic points of view its essential to differentiate the three entities, i.e., LBL, HL and PMBCL. The pathological diagnosis of pediatric mediastinal lymphomas is quite challenging for general histopathologists. In this review, we describe the pathology, genetics, differential diagnosis, treatment, prognosis, and a simplified histopathological and immunophenotypical approach to differentiate the pediatric mediastinal lymphomas.