Fig. 19.105 Smear of pleural effusion depicting mesothelioma cells.
The largest cell contains yellow cytoplasmic lakes of glycogen. Smear of
pleural fluid (Papanicolaou x LP). Reproduced with permission from Naylor B:
Pleural, peritoneal, and pericardial fluids. In: Keebler CM, Somrak TM (eds)
Manual of Cytotechnology,
7th edn. Chicago: ASCP Press; 1993.
Fig. 19.106 Smear of pleural effusion depicting tissue fragments of
mesothelioma in a dense, finely granular, orangeophilic background
caused by a high concentration of hyaluronic acid in the specimen. To the
naked eye the specimen was hyperviscous (Papanicolaou x LP). Reproduced
with permission from Naylor B: The exfoliative cytology of diffuse malignant
J Pathol Bacteriol
(Fig. 19.109) which may cause the cells to be mistaken for kerat-
inized squamous epithelial cells; such change rarely occurs in
benign mesothelial cells.
Because it is important to distinguish between mesothelioma
and metastatic adenocarcinoma in serous fluids, not only from
the epidemiologic and therapeutic aspects but also from the
aspect of asbestos-related litigation, immunocytochemistry and
electron microscopy have been widely used to make this dis-
tinction. Whitaker also pointed out the usefulness of using cell
blocks in the diagnosis of mesothelioma.176 Not only do they
demonstrate the presence of collagen cores in some cohesive
clusters of mesothelioma, they also provide a readily available
medium for immunocytochemical investigation.
Fig. 19.107 Smear of pleural effusion depicting mesothelioma cells in a
heavy background of gray-blue precipitate of hyaluronic acid (Papanicolaou
Fig. 19.108 Cell block of pleural effusion depicting an acinus of
mesothelioma in which are dark blue precipitated specks of hyaluronic acid
(Papanicolaou x HP).
Fig. 19.109 Smear of pleural effusion depicting degenerating
mesothelioma cells: shrinking of cell size, smoothness of nuclear
chromatin, and eosinophilia of cytoplasm. Such cells could be mistaken for
benign or malignant squamous epithelial cells (Papanicolaou x LP).