Diagnostic Cytology
gynecologic practice. It is virtually confined to patients undergo-
ing abdominal exploration for gynecologic neoplasms to detect
peritoneal dissemination of cancer cells. Peritoneal dialysate
from patients undergoing long-term peritoneal dialysis for renal
failure is seldom submitted for cytologic examination.
Collecting Serous Effusions
The fluid is collected into a clean, dry container, which need not
be sterile, and sent to the laboratory as soon as possible. If the
fluid cannot be sent immediately, it should be stored in a refrig-
erator at 4°C and not allowed to freeze. We do not require anti-
coagulant or fixative to be added to the fluid. Anticoagulation
by adding heparin to the receptacle before the fluid is collected
does not interfere with cytologic detail.
Formalin, alcohol, or any other kind of cellular preserva-
tive must not be added to specimens of serous fluid sent to our
laboratory. Formalin not only prevents cells from adhering well
to a slide but also interferes with the quality of staining by the
Papanicolaou method. Adding alcohol causes some precipita-
tion of protein in virtually all specimens, thereby interfering
with adherence of the cells to the slide. Apart from these crit-
icisms of the use of formalin or alcohol, neither is necessary
because keeping the specimen at refrigerator temperature, even
for several days, preserves cells well (Fig. 19.1).
Gross Appearance of Serous Effusions
The appearance to the naked eye of a serous effusion sometimes
reveals clues about the cause of the effusion and the nature of
its cellular contents. Therefore, for every serous effusion received
by the laboratory, note should be made of its volume, color,
clarity, and any unusual physical features, such as malodor,
opalescence, or high viscosity.
Many serous effusions are noticeably bloodstained. In a sur-
vey carried out in our laboratory, 46% of pleural (n = 179) and
27% of peritoneal (n = 104) effusions were visibly bloodstained,
a term used for effusions whose color ranges from orange to deep
red. A commonly held belief is that heavily bloodstained effu-
sions are likely to be caused by cancer and that such effusions are
more likely to contain cancer cells. However, of the 60 deep-red
Fig. 19.1 Smear of well-preserved adenocarcinoma cells prepared from
a pleural effusion that had been stored in the refrigerator at 4°C for 14 days
after collection (Papanicolaou x MP).
effusions in the combined series (n = 283), only 13 contained
cancer cells. Furthermore, of the 58 effusions that contained can-
cer cells, 30 were bloodstained and 28 were not, thus showing
that effusions containing cancer cells are just as likely as not to
be bloodstained, an observation described previously.1,2
A serous effusion occasionally contains so many cancer cells
that if allowed to stand and sediment spontaneously, the cells
form a thick, whitish-yellow layer at the bottom of the con-
tainer. Spontaneously occurring sediment of similar appearance
may develop in fluids containing numerous neutrophilic leuko-
cytes. Such purulent fluids may be malodorous owing to a high
bacterial content. Pleural fluid from a patient with rheumatoid
pleuritis may contain a heavy, whitish, flocculent sediment, and
the supernatant may have the appearance of fruit juice, such as
lime or pineapple juice.
Individual particles of cancer in a serous effusion may occa-
sionally be large enough to be visible to the naked eye. Such
particles, strikingly illustrated by de Vries, may be spheroids,
ellipsoids, or similar shapes.3 Figure 19.2 is a striking example of
particles of metastatic squamous cell carcinoma in pleural fluid
in which the particles were about the size and shape of sesame
seeds. However, particles visible to the naked eye are usually
spheroids, not more than 1 mm in diameter (Fig. 19.3). Fluids
containing particles of cancer visible to the naked eye produce
excellent cell blocks.
Fluids containing numerous pigmented melanoma cells may
be chocolate brown (Fig. 19.4). Much lighter brown are effu-
sions containing many hemosiderophages, a manifestation of
old hemorrhage into the serous cavity. Effusions from patients
who are jaundiced or that are a result of leakage of bile into
the peritoneal cavity may have a rather dark brown-orange or
greenish appearance that remains with the supernatant after the
specimen has been centrifuged.
Serous effusions caused by diffuse malignant mesothelioma of
epithelial type often contain a high concentration of hyaluronic
acid,4 which may increase the viscosity of the fluid so much that
it may has the consistence of thin honey. We have also observed
such high viscosity due to hyaluronic acid in a pleural effusion
containing cells of metastatic Wilms tumor. An effusion from
the peritoneal cavity of a patient with pseudomyxoma peritonei
(gelatinous ascites) is extremely difficult to aspirate because of
Fig. 19.2 Particles of squamous cell carcinoma visible to the naked eye
extracted from a pleural effusion (unstained, natural size).
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