Pleural, Peritoneal, and Pericardial Effusions
Fig. 19.83 Smear of pleural effusion depicting a fragment of
nonkeratinizing squamous cell carcinoma of bronchus. Unlike a cluster
of mesothelial or adenocarcinoma cells, this cluster of cells has a loose,
angulated and "untidy” appearance (Papanicolaou x MP).
Fig. 19.84 A smear of the previous specimen depicting a pair of
nonkeratinizing third type cells of squamous cell carcinoma. Under the
microscope, delicate concentric lines are visible in the cytoplasm of the larger
cell; such lines are evidence of squamoid differentiation (Papanicolaou x OL).
recognized in histologic sections that squamous cell carcinomas
frequently contain a few cells that exhibit such vacuolization.
In fact, in our review of the routinely prepared histopathologic
sections of the 46 squamous cell carcinomas in this series, some
degree of cytoplasmic vacuolation of the carcinoma was found
in 37 (80%). In contrast to the cells of adenocarcinomas, the
cells of squamous cell carcinomas in serous effusions, both
vacuolated and nonvacuolated, tend to be isolated.
The incidence of squamous carcinoma cells in serous effu-
sions is not high, and if the cells do not show clear evidence
of keratinization it is easy to overlook their squamous origin.
However, one should expect that virtually every example of met-
astatic squamous cell carcinoma in a serous effusion will, as in
our series, be derived from a patient known to have or to have
had squamous cell carcinoma.
Key features of squamous cell carcinoma
• Most originate from carcinomas of lung, larynx, or
female genital tract;
Fig. 19.85 Smear of pleural fluid containing a metastatic keratinizing
third type cell of laryngeal squamous cell carcinoma (Papanicolaou x HP).
Reproduced with permission from Smith-Purslow MJ, Kini SR, Naylor B: Cells
of squamous cell carcinoma in pleural, peritoneal and pericardial fluids. Origin
Fig. 19.86 Smear of pleural effusion depicting a keratinizing squamous
carcinoma cell of metastatic bronchogenic carcinoma in which the nucleus
is undergoing lysis (Papanicolaou x MP).
• Keratinized cells have orange cytoplasm and round,
tadpole-like or fiber shapes;
• Non-keratinized cells are usually round; they may
form two-dimensional cohesive clusters; and
• Degenerative cytoplasmic vacuoles may be seen.
Small-Cell Anaplastic Carcinoma
These carcinomas are best exemplified by the small-cell carci-
noma of the lung, a major histologic type of lung cancer. The
cytologic presentation in serous effusions of this highly aggres-
sive carcinoma has been well documented.9'14'20,32,117,183'184
The cells of small-cell carcinoma in smears stained by the Papan-
icolaou method or in stained wet films are isolated or in small
cohesive clusters (Fig. 19.90). The cells are small, about twice
the diameter of lymphocytes. They also show a slight degree of