ABSTRACT
Lymph nodes act as a scaffolding system and home for lymphocytes, monocytes, and histiocytes in the lymphatic system. The capsule and its extension within the lymph node parenchyma together with a reticular meshwork form the supportive elements of the lymph node. The mantle zone in the lymph nodes is usually homogeneous without an overt marginal zone, typical for follicles in the spleen. Evaluation of the lymph node requires correlating architectural characteristics with cytologic features. Polarization helps to differentiate reactive follicles from follicular lymphoma. The size of lymphoid cells is categorized by comparing the nuclei of histiocytes or endothelial cells. High-grade tumors with blastic features often show admixtures of histiocytes, which engulf cellular debris and give rise to a so-called starry-sky pattern when the lymph node is examined at low power. The lymph node is enlarged with mixed follicular and paracortical hyperplasia, small foci of necrosis, and a pleomorphic infiltrate composed of lymphocytes, histiocytes, and plasma cells.
