Pleural, Peritoneal, and Pericardial Effusions
Fig. 19.113 Cell block of pleural effusion depicting metastatic duct
cell adenocarcinoma of breast. The partly hollow fragment of
adenocarcinoma has a cribriform appearance, replicating that frequently
seen in histologic sections of ductal carcinoma of the breast (H&E x LP).
The presence of metastatic breast carcinoma cells in a pleu-
ral effusion does not always denote that death is imminent: we
have records of patients with such effusions who survived for
up to four years after the diagnosis of adenocarcinoma in the
The cytologic picture of metastatic breast carcinoma has been
well documented.14,32,78,115,117 Breast carcinoma cells in a serous
effusion (almost always a pleural effusion) are usually abundant
and of medium size (see Fig. 19.8). One classic presentation of
ductal adenocarcinoma of the breast is as the compact, dense,
smoothly round spheroids known as proliferation spheres.170
Because of the high optical density of these spheres in smears
(Fig. 19.78), it is generally impossible to discern in them indi-
vidual cytologic features of malignancy; however, cell-block
preparations of such fluids clearly reveal the adenocarcino-
matous nature of the spheres (see Fig. 19.79). Even though in
some of these fluids most of the adenocarcinoma cells seem to
be forming these dense spheres, careful inspection will reveal
isolated adenocarcinoma cells in the background. In smears,
the hollowness of proliferation spheres can be discerned by
the somewhat empty appearance of the sphere (see Fig. 19.78),
and careful focusing reveals that the cells in the center of the
sphere are on two different planes. This hollowness of prolif-
eration spheres may be only partial, a feature that can impart
a cribriform pattern to the fragment of adenocarcinoma (Fig.
19.113), thereby replicating the pattern of intraductal adenocar-
cinoma commonly seen in histologic sections of carcinoma of
the breast.
Proliferation spheres are a characteristic of duct cell carcinoma
of the breast; however, we have occasionally observed them in
effusions containing neoplastic cells from other sources.228
Lobular carcinomas of the breast are typically manifested as
numerous small, isolated carcinoma cells that could be mistaken
for small histiocytes or small mesothelial cells, especially the lat-
ter (see Fig. 19.114). However, apart from the great number of
fairly uniform isolated cells, individual cells show some irregu-
larity of nuclear shape and prominent nucleoli. Also, the cyto-
plasm of cells of lobular carcinomas (like that of some duct cell
Fig. 19.114 Smear of pericardial effusion depicting metastatic lobular
adenocarcinoma of the breast. All of the cells in this field are small
adenocarcinoma cells, some forming a caterpillar-like chain
(Papanicolaou x HP).
carcinomas) frequently displays one or more cytoplasmic vacu-
oles lined by microvilli and containing a droplet of mucus.177
Cells of lobular carcinoma also have a tendency to form small,
caterpillar-like chains similar to those commonly seen with
small-cell anaplastic carcinoma. However, they are quite differ-
ent from small-cell anaplastic carcinoma: the cells possess easily
visible cytoplasm, the nuclei are not as hyperchromatic, and the
nucleoli are visible. The picture of a hypercellular specimen con-
taining numerous small round neoplastic cells of fairly uniform
shape and size could be mistaken for lymphoma. However, in
every example of metastatic lobular carcinoma that we have seen
it was possible to find small groups of distinctly cohesive cells,
which denoted their epithelial origin.
Key features of carcinoma of the breast
• Seen almost exclusively in patients known to have or
have had breast carcinoma;
• Frequent presence of hollow proliferation spheres; and
• Lobular carcinoma: many innocent-appearing small
cells, some forming caterpillar-like chains
Neoplasms of the ovary
By far the commonest neoplasms of the ovary are those which
have a glandular nature and show a wide range of differentia-
tion, from benign cystadenomas through ovarian tumors of low
malignant potential to frankly invasive adenocarcinomas of var-
ious degrees of differentiation. Ovarian carcinoma is a frequent
cause of ascites and, to a much lesser extent, pleural effusion. In
fact, the first clinical manifestation of ovarian carcinoma often
is abdominal distention due to a peritoneal effusion that con-
tains carcinoma cells. Much less frequently occurring ovarian
neoplasms that will be featured in this section are malignant
teratoma and dysgerminoma.
The cells of ovarian adenocarcinomas in serous effusions are gen-
erally easily recognizable. The number of adenocarcinoma cells
is usually high, and the cells often present as large acinar or pap-
illary cohesive clusters mixed with numerous isolated cells, many
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