Fig. 15.4 Large superficial and smaller pyramidal or basal cells. Some of
Fig. 15.6 Renal tubular epithelial cells. The cells are of a size similar
the superficial cells are binucleated and contain nucleoli (Papanicolaou x MP).
to that of immature urothelial cells and have uniform, round nuclei
(Papanicolaou x MP).
Fig. 15.5 Urothelial cells with prominently vacuolated cytoplasm
(Papanicolaou x MP).
Transitional epithelial cells are present in all urine specimens
(see Fig. 15.1). In voided urine, they occur singly or in the
form of loosely cohesive clusters or sheets. They vary consider-
ably in size (Figs 15.2 to 15.4), with a cell diameter from 9 to
40 pm and a cell size of 75 to 1400 pm2 with a mean of 340 pm2.
The cytoplasm is opaque, granular, or vacuolated (Fig. 15.5).
Renal tubular epithelial cells are rarely found in voided or cath-
eterized urine, except in cases of renal transplant rejection or
renal parenchymal disease (Fig. 15.6). The renal tubular epithe-
lial cells have round nuclei and usually a granular cytoplasm.
Many transitional cells are elongated, and columnar cells may
be present (Fig. 15.7). The nuclei are usually round, but they
may be irregular in outline or may appear pyknotic. Large super-
ficial or binucleated cells, often with relatively large nuclei that
have a salt-and-pepper appearance, are particularly common in
bladder washings and in ureteral catheterization specimens. The
nuclei average 7.5 pm in diameter and vary from 10 to 90 pm2,
with a mean of 36 pm2.2,16 The nucleoplasm is usually bland
Fig. 15.7 Columnar cells in voided urine (Papanicolaou x MP).
or vesicular, and the chromatin pattern of most nuclei is finely
granular or has a salt-and-pepper appearance (Fig. 15.8) . Small
nucleoli are rarely present. The described three cell types of the
urothelium—namely, the large, often multinucleated superficial
cells, the intermediate pyramidal cells, and the cuboidal cells
adjacent to the basement membrane—can be identified in sin-
gle cell suspensions prepared from tissues and in voided and
catheterized urine specimens. Eldidi and Patten reported that
the basal cells have a mean cytoplasmic area of 82 pm2, a mean
nuclear area of 24 pm2, and a relative nuclear area of 29 pm2.16
They are predominantly oval, with basophilic, dense cytoplasm
and single nuclei. The pyramidal cells are larger, with a mean
cell area of 229 pm2 and a mean nuclear area of 40 pm2. They
are also predominantly oval with a basophilic cytoplasm and
well-defined cell borders. The nuclei are generally single and
oval. The superficial cells are considerably larger, with a mean
area of 500 pm2 and a mean nuclear area of 64 pm2. The relative
nuclear area is 13%. These cells are less basophilic. Binucleation
occurs in 19%, and 3% are multinucleated. Most nuclei are oval.
Nucleoli are more prominent than in the smaller cells. Pyrami-
dal or intermediate cells predominate in voided urine, but 42%