This cytospin was prepared from a pleural fluid obtained from a patient with multiply recurrent non-Hodgkin lymphoma. The patient had repeated thoracentesis to remove excess fluid and to improve his quality of life while on palliative therapy.
The three large mononuclear cells indicated by the blue arrows are lymphoma cells. Notice their large total size and high N/C ratio compared to the background lymphocytes. The lymphoma cells contain scant amounts of basophilic cytoplasm with a few fine cytoplasmic vacuoles.
Notice also the wide range of normal and reactive cells in the background. In patients with recurrent malignant effusions, it is not uncommon to see such mixed cell populations.
It is important to look for lymphoma cells in known lymphoma patients, as these cells may be present in low numbers during and after therapy, rather than in the large numbers that are usually present upon initial diagnosis.