PART TWO
Diagnostic Cytology
Fig. 19.98 Papillary diffuse malignant mesothelioma arising from parietal
pleura. The neoplasm was infiltrative (H&E x LP). Reproduced with permission
from Naylor B: The exfoliative cytology of diffuse malignant mesothelioma.
J Pathol Bacteriol
1963;86:293-298.
Fig. 19.99 Smear of pleural effusion depicting tissue fragments of diffuse
malignant mesothelioma of the epithelial type. This specimen and
those illustrated in Figs 19.99 through 19.103 are from the pleural effusion
associated with the mesothelioma illustrated in Fig. 19.98. Smear of pleural
fluid (Papanicolaou x MP). Reproduced with permission from Naylor B: The
exfoliative cytology of diffuse malignant mesothelioma.
J Pathol Bacteriol
1963;86:293-298.
and peritoneal fluids from patients with diffuse malignant mes-
othelioma has enabled us to reach the point at which we con-
fidently and accurately diagnose most cases of mesothelioma
from routine cytologic preparations. The diagnosis of mesothe-
liomas without resort to surgery is a desirable goal because
mesotheliomas have a tendency to grow into thoracotomy and
laparotomy wounds; they may even spread along the tract of a
thoracentesis needle.
Figure
19.98 illustrates a histologic section of a well-
differentiated papillary diffuse malignant mesothelioma of
pleura and Figs 19.99 to 19.103 illustrate cells exfoliated from
the same mesothelioma into the accompanying pleural effu-
sion. In contrast to the picture of mesothelial hypertrophy
and hyperplasia, the cells of mesotheliomas tend to be more
profuse, often extremely so, and to form large cohesive clus-
ters (Fig. 19.99) accompanied by many smaller clusters and
Fig. 19.100 Smear of pleural effusion depicting two pairs of mesothelioma
cells with the cytoplasmic staining reaction and intercellular articulation
typical of benign mesothelial cells. In contrast to typical benign mesothelial
cells, these cells are larger and have a lower nucleocytoplasmic ratio
(Papanicolaou x HP). Reproduced with permission from Naylor B: The
exfoliative cytology of diffuse malignant mesothelioma.
J Pathol Bacteriol
1963;86:293-298.
Fig. 19.101 Smear of pleural effusion depicting a pair of mesothelioma
cells. Note the typical mesothelial articulation and the prominent nucleoli
(Papanicolaou x HP). Reproduced with permission from Naylor B: The
exfoliative cytology of diffuse malignant mesothelioma.
J Pathol Bacteriol
1963;86:293-298.
isolated cells, all exhibiting distinct morphologic characteristics
of benign mesothelial cells (Figs 19.100 to 19.103). Collectively,
the individual mesothelioma cells are larger than benign mes-
othelial cells, although their nucleocytoplasmic ratio is often
lower (Fig. 19.101). Their nuclei also tend to be smoothly round
or oval (Figs 19.100 and 19.101), in contrast to the more angu-
lated nuclear outline typical of adenocarcinoma. Nucleoli are
prominent (Fig. 19.101), and the nuclear chromatin is slightly
increased in density and more coarsely granular than in benign
mesothelial cells, a subtle feature that seldom can be relied on
to reveal the malignant nature of the cells.
Such neoplastic mesothelial cells may be so similar to benign
mesothelial cells that it may take an experienced eye to perceive
the differences between them. From our experience, we have
found that once we have determined that the cells in question
are of mesothelial lineage, the most significant features pointing
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