Pleural, Peritoneal, and Pericardial Effusions
Fig. 19.53 Rheumatoid pleuritis. A giant multinucleated histiocyte in
a background of amorphous granular material. Smear of pleural fluid
from the same patient as in Fig. 19.51 (Papanicolaou x HP). Reproduced with
permission from Nosanchuk JS, Naylor B: A unique cytologic picture in pleural
fluid from patients with rheumatoid arthritis.
Am JClin Pathol
quality of the stain), and often has a finely granular ground-glass
appearance. The nuclei of these cells are frequently multiple and
are usually round or oval, although they may be quite elongated
as they conform to the shape of the cell. The giant multinucle-
ated round or oval histiocytes have a diameter of up to about
70 pm and may contain 20 or more nuclei (Fig. 19.53). Apart
from the size and shape of these cells and their large number of
nuclei, their morphologic features are the same as those of the
elongated histiocytes. In addition, various cellular forms that
can be found are morphologically transitional between these
elongated slender histiocytes and the giant round multinucle-
ated histiocytes. A detailed scanning and electron microscopic
and immunocytochemical study of cells in a pleural fluid show-
ing the picture of rheumatoid pleuritis strongly supported the
belief that all of the various types of cells described previously
are histiocytes.96
N ecrotic Background M aterial
The granular necrotic background material, formed by necro-
sis and disintegration of the histiocytes, may be so abundant
that it dominates the microscopic picture (Fig. 19.54). Its stain-
ing reaction in Papanicolaou-stained smears is various shades
of red, pink, orange, or green, depending on the thickness of
the smear and the quality of the stain. In smears, the granules
range from about 5 to 50 pm in diameter. They are amorphous
and possess "soft," fluffy outlines. In cell blocks stained with
hematoxylin and eosin, the granular material is seen as large,
well-defined, distinctly eosinophilic, dense, island-like aggre-
gates (Fig. 19.55), which may have been formed by compaction
of the granules during centrifugation of the specimen; it is obvi-
ous that this granular material consists of necrotic cells because
some particles retain the elongated form of viable histiocytes;
Fig. 19.55 also illustrates a necrotic giant multinucleated his-
tiocyte before it disintegrated to blend with the surrounding
Rheumatoid effusions may also contain various other cells
such as neutrophils, lymphocytes, and small mononuclear his-
tiocytes. Because of the typically long-standing nature of rheu-
matoid effusions, many of these background cells also become
Fig. 19.54 Rheumatoid pleuritis. A field dominated by amorphous granular
material in which there is a solitary giant multinucleated histiocyte. Smear of
pleural effusion from the same patient as in Fig. 19.51 (Papanicolaou x LP).
Fig. 19.55 Rheumatoid pleuritis. Compact islands of eosinophilic granular
material in which there is a necrotic giant multinucleated macrophage.
Cell block of pleural effusion (H&E x LP).
necrotic and contribute to the granular material. Many of these
necrotic cells also undergo karyorrhexis before the cell disin-
tegrates to produce a picture that, at first glance, resembles a
purulent effusion (Fig. 19.56). Mesothelial cells were noticeably
absent from almost all our rheumatoid effusions that showed
the cytologic picture of rheumatoid serositis, being found (in
small numbers) in only 1 of our 24 specimens.
The complete cytologic triad of rheumatoid serositis may not
be present in every cytologically diagnosable specimen. How-
ever, it may be possible to make the correct diagnosis when only
one or two of the three components are present. All three com-
ponents were present in only 12 of 24 cytologically diagnos-
able pleural fluids, two components were present in 7 of the
fluids, and one component, the granular necrotic material, was
found in 23 of the 24 fluids. The three cytologic components
are equally discernible in smears, cell-block preparations, and
toluidine blue-stained wet films; the best diagnostic results are
achieved by using all three methods.
The cytologic picture just described is not only unique but
is also pathognomonic of rheumatoid pleuritis or pericardi-
tis, an observation that has been amply confirmed by our own
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