19
Pleural, Peritoneal, and Pericardial Effusions
Fig. 19.118 A histologic section of a malignant teratoma of the ovary
which features a particularly undifferentiated portion of the neoplasm.
The inset displays a fragment of poorly differentiated cancer cells in the
peritoneal effusion (tissue: H&E x LP; cells: Papanicolaou x OI).
Fig. 19.120
k of peritoneal effusion depicts strips of mucin-
producing appendiceal cystadenoma of a man. Because of its mucoid nature
this effusion was extremely difficult to aspirate, typical of pseudomyxoma
peritonei (H&E x LP).
Fig. 19.119 Smear of peritoneal effusion depicting cells of an ovarian
dysgerminoma. The inset illustrates a histologic section of the neoplasm
(cells: Papanicolaou x HP, tissue: H&E x HP).
Pseudomyxoma Peritonei
Pseudomyxoma peritonei (gelatinous ascites) is a poorly under-
stood condition characterized by the massive accumulation of
abundant mucinous material in the peritoneal cavity, associated
mainly with mucin-producing adenoma or adenocarcinoma of
the appendix or ovaries. This massive peritoneal accumulation
is extremely difficult to aspirate because of its thick mucoid con-
sistence. The condition may ultimately be fatal, usually owing to
intestinal obstruction.
When pseudomyxoma peritonei is caused by rupture of a
mucus-producing adenoma of the colon or appendix, the cells
released into the mucoid fluid are non-atypical, whereas in cases
of mucin-producing adenocarcinoma the cells are frankly atypi-
cal. The three cases seen in our laboratory have been caused by
rupture of appendiceal adenomas, two in men and one in a
woman.
The aspirated fluid is difficult to smear and, except for the
occasional histiocyte, may appear to be devoid of cells. How-
ever, if enough fluid is examined, especially by the smear and
cell-block techniques, it is possible to find groups of neoplas-
tic cells in honeycomb-like sheets or strips as illustrated in Fig.
19.120.21,232-236
Key features of pseudomyxoma peritonei
• Difficult to aspirate from peritoneal cavity;
• Mucin with occasional gland cells, isolated or in
clusters or strips; and
• Cells non-atypical (adenomatous) or atypical
(carcinomatous).
carcinoma of the Gastrointestinal Tract
As the incidence of gastric carcinoma declines, cells from this
lesion in serous effusions are now being encountered with less
frequency; most are seen in peritoneal effusions. The cytologic
presentation of gastric carcinoma has been that of small clusters
of adenocarcinoma cells accompanied by many isolated adeno-
carcinoma cells, some with cytoplasmic vacuoles imparting a
signet ring appearance to the cells. Also many of the isolated
carcinoma cells have a scanty amount of cytoplasm which may
simulate lymphoma (see Fig. 19.80).
Despite the frequency of colonic adenocarcinoma as a cause
of death, the finding of cells from this neoplasm in a serous
effusion is not a common event; when found they are usually
in peritoneal fluid. Isolated cells were very few; the neoplasm
was often seen as tissue fragments embedded in mucin (Fig.
19.121).
Key features of carcinoma of gastrointestinal tract
• Gastric: signet ring adenocarcinoma cells and cells
with little cytoplasm; and
• Colon: mucin-producing adenocarcinoma.
Miscellaneous carcinomas
We have seen examples of adenocarcinomas of endometrial,
prostatic, pancreatic, biliary, cervical, thyroid, renal, and hepatic
origin in serous effusions. Their appearance varied greatly
from small cells of fairly uniform size and shape, not unlike
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