[Lymphomas of the thymus and mediastinum]

Lymphocyterich lesions account for the majority of relevant differential diagnoses in the anterior mediastinum and include non-neoplastic and neoplastic entities. With only 10-15% of cases, lymphomas account for a relatively small proportion of these. A systematic approach and consideration of epidemiological and clinical background information are crucial for a correct diagnosis, particularly in the case of small biopsies. A few entities dominate among mediastinal lymphomas: nodular sclerosing Hodgkin lymphoma (NSCHL) is the most common form, accounting for 50-70% of cases, followed by primary mediastinal large B‑cell lymphoma (PMBL) and T‑lymphoblastic lymphoma (T-LBL). Epidemiologically, all of these tumors occur predominantly in children and young adults; all other lymphomas are rare and mostly affect older patients. In this context, typical practical diagnostic challenges include the distinction of B‑cell lymphomas from other B‑cell-dominated lesions, the distinction of T‑LBL from thymomas, the subtyping of sclerotic lymphomas (NSCHL, PMBL, gray zone lymphomas) and their separation from other sclerosing processes. This overview focuses on the discussion of these practice-relevant diagnostic problems.