Pleural fluid of an 88-year-old male patient with a history of lung tuberculosis. a Numerous small lymphocytes in the sediment of the fluid, practically without mesothelial cells. Papanicolaou. Original magnification ×400. b FC demonstrating a reactive pattern with numerous CD3-positive T cells (83%) and a small CD19-positive B-cell population (9%) without light chain restriction (κ/λ ratio of 1:1), corresponding to a reactive lymphatic population in the effusion specimen. Lymphocyte-rich pleural effusions with a low mesothelial cell count are often seen in tuberculous pleurisy.