Radiological assessment of extranodal lymphoma: spectrum of disease

Abstract

Primary extranodal lymphoma manifestation in the narrow sense is the term used to define the primary organ manifestation of a malignant lymphoma, excluding the thymus, spleen, Waldeyer's tonsillar ring, the appendix and Peyer's patches. However, in the clinical routine the term is also used for the secondary organ manifestation of underlying lymphoproliferative disease. Primary extranodal lymphomas are mainly non-Hodgkin lymphomas; there is primary extranodal manifestation of Hodgkin's disease in only about 1% of the cases. Among the extranodal NHL, the highly malignant forms predominate. A major exception is MALT lymphomas, which mainly show low slow growth. In the past, they were considered to be pseudolymphomas because of their slow and localized tumor growth. They were included as an entity of their own for the first time in the Revised European American Lymphoma (REAL) classification of 1994. The incidence data vary between < 10% and 25% for primary extranodal manifestation. The major reason for this is the difference in extranodal regions because of classification. Secondary organ involvement of an NHL occurs in up to 40% of the cases in the long-term course of the disease in primary nodal lymphomas. Secondary organ involvement is frequently diagnosed in AIDS patients who develop an AIDS-related lymphoma (85% of cases). The following contribution reports on the radiological imaging of extranodal lymphoma manifestation in the thoracoabdominal region.