Fig. 19.10 Pleural effusion containing flat, angulated cholesterol crystals,
a manifestation of long-standing effusion, in this case caused by rheumatoid
pleuritis (toluidine blue-stained wet film, polarized light x MP).
which are brilliantly highlighted by polarized light (Fig. 19.10).
Another crystalline curiosity revealed by the wet-film technique
is Charcot-Leyden crystals (Fig. 19.11), which may be found
in effusions containing numerous eosinophilic leukocytes.8
Wet films reveal psammoma bodies, not because they take up
the stain but because they do not react with toluidine blue and
therefore stand out unstained against the surrounding stained
cells (Fig. 19.12). Bloodstained effusions may contain sheaves
of brown hematoidin crystals, formed by the breakdown of
hemoglobin. The cellular fragments known as detached cili-
ary tufts (DCTs), found in certain types of peritoneal fluid, are
vigorously motile in the fresh state, a property detectable only
by using a wet film (see "Detached Ciliary Tufts," later).
Apart from these advantages and applications, toluidine
blue-stained wet films are a joy to look at. We cannot imagine
working in a cytopathology laboratory that does not use them.
Key features of stained wet films
• May allow rapid diagnosis and reporting;
• Allow "super-positive" specimens to be segregated; and
• Reveal psammoma bodies and crystals.
Usefulness of Cell-Block Preparations
Although the use of cell blocks of serous effusions is not standard
practice in all laboratories, we find it indispensable. Specimens
that are not anticoagulated frequently contain a clot that may
be voluminous. Such a clot may have developed rapidly after
the fluid was aspirated, enmeshing virtually all of the neoplastic
cells in the specimen. Consequently, smears prepared from the
remaining fluid after the clot has been removed may be devoid
of neoplastic and other cells. In such a situation, sections of the
spontaneously formed clot frequently reveal numerous, obvious
In a series of 863 serous effusions that contained cancer
cells and that we had examined by both smear and cell-block
techniques, both techniques gave positive results in 696 cases.
With 113 specimens, only the smears were positive, and with 54
specimens, only the cell block was positive. Cell blocks therefore
enhanced our positive results by 6.7%, a worthy and ultimately
Fig. 19.11 Pleural effusion containing Charcot-Leyden crystals in a
background of eosinophils, lymphocytes, and erythrocytes (toluidine blue-
stained wet film x MP).
Fig. 19.12 Peritoneal effusion containing a papillary fragment of ovarian
adenocarcinoma containing a psammoma body (toluidine blue-stained
wet film x MP).
A discrepancy between positive smears and negative cell
blocks can be explained by a slowly forming spontaneous
clot, thereby allowing cancer cells to sink to the bottom of
the container. In the cell block the spontaneously formed clot
composed of dense magenta fibrin would contain very few, if
any, cancer cells, whereas the induced clot prepared from the
sediment obtained by centrifugation of the unclotted portion
of the specimen would contain many (Fig. 19.13). The reverse
situation can also take place.
Cell-block preparations may also reveal certain histologic
aspects of a neoplasm such as papillary, acinar, or duct-like
formations. Also extremely well demonstrated in cell blocks
are psammoma bodies, which may be difficult or impossible
to detect in the permanent smears.
Cell blocks reveal other interesting histologic or cytologic
entities, some mere curiosities but others of importance. Figure
19.14 illustrates a fragment of liver in the cell block of peritoneal
fluid obtained when the paracentesis needle traversed the liver
on its way to the peritoneal cavity; retrospective analysis of the
smears revealed only an occasional hepatocyte. In our material,
cell blocks have also revealed granulation tissue (Fig. 19.15),
a manifestation of pleural inflammation, cholesterol clefts in