The retroperitoneum is the space between the parietal peritoneum anteriorly and the transversalis fascia posteriorly. Most
retroperitoneal tumors arise from mesenchyme, neurogenic tissue, or embryonic rests. By this definition and by including lymph
nodes as a retroperitoneal organ, lymphoma is not considered a primary retroperitoneal tumor.
Key words Retroperitoneum - Lymph nodes - Lympadenopathy
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