Page 250 - Clinical Hematology Atlas

234 SECTION FIVE MISCELLANEOUS

MESOTHELIAL CELLS

Mesothelial cells are shed from membranes that line body cavities and are often found in
serous fluids.

FIGURE 24–19 Mesothelial cell with pale blue FIGURE 24–20 Mesothelial cells with deeply
cytoplasm (pleural fluid 31000). basophilic cytoplasm (pleural fluid 31000).

SHAPE: Pleomorphic
SIZE: 12-30 mm
NUCLEUS: Round to oval with smooth nuclear borders; nucleus may be eccentric or multinucleated,
making the distinction between the mesothelial and plasma cell difficult at times
Nucleoli: 1-3, uniform in size and shape
Chromatin: Fine, evenly distributed
CYTOPLASM: Abundant, light gray to deeply basophilic
Vacuoles: Occasionally
NOTE: Mesothelial cells may appear as single cells in clumps or sheets. The clumping of cells
to one another and the variability of appearance require careful observation to accurately
differentiate mesothelial cells from malignant cells. Three characteristics can aid in this
determination:
1. Mesothelial cells on a smear tend to be similar to one another.
2. The nuclear membrane appears smooth by light microscopy.
3. Mesothelial cells maintain cytoplasmic borders. When appearing in clumps, there may
be clear spaces between the cells. These spaces are often referred to as “windows.”