Figure 2

Photomicrographs of excisional lymph node biopsy. Panel A, Lymph tissue demonstrating expanded sinuses with histiocyte infiltration and distorted architecture. (HE stain, Original magnification 40 ×). Panel B. A higher magnification view demonstrating lymphocytes inside histiocytes (HE stain, Original magnification 400 ×). Notice pale cytoplasm, ovoid nuclei with a single nucleolus and open chramatin of histiocytes in contrast to lymphocytes with smaller round nuclei and dense chromatin. Examples of emperipolesis are noted by arrows; grey arrows identify examples of single lymphocytes within histiocytes and a curvilinear group of five lymphocytes are bracketed by the black arrows. Panel C. This panel depicts immunohistochemical evaluation for S-100. The large histiocytes are immunoreactive to S100 with both cytoplasmic and nuclear staining and the unstained cells in the cytoplasm of histiocytes are engulfed lymphocytes (Immunohistochemical stain, Original magnification 40×). Panel D. The panel contains a representative HE stained section from tissue obtained from the abdominal mass at autopsy depicting the diffuse large B cell non-Hodgkin's lymphoma diagnosed, the insert depicts positive anti-CD20 immunohistochemical staining, (Original magnification 100 ×).