15
Urinary Tract
Fig. 15.8 Degenerated urothelial cells showing slight anisonucleosis
and salt-and-pepper chromatin in ureteral catheterization specimen
(Papanicolaou x MP).
Fig. 15.9 A large multinucleated urothelial cell of the type seen most
commonly in ureteral and pelvic washings (Papanicolaou x MP).
of cells in washings are superficial. They are particularly promi-
nent in ureteral catheterization specimens. Cell aggregates and
cytoplasmic molding are also more common in catheterized
rather than voided specimens. The large multinucleated cells
prominent in ureteral or renal pelvic washings may contain as
many as 20 or 30 centrally crowded nuclei (Fig. 15.9).
Squamous cells of intermediate and less commonly of
superficial type are frequently present, more often in women
(Fig. 15.10). They exfoliate from portions of the urethra lined by
squamous epithelium, from areas of squamous metaplasia in the
urinary bladder, or from zones of squamous epithelium that may
be found in the trigone of women. Some squamous cells may
represent vaginal contamination. The squamous cells present
do reflect the effect of estrogen. Areas of squamous metaplasia
are often regular and well differentiated, and the exfoliated
squamous cells cannot be distinguished from those that exfoli-
ate from areas where squamous epithelium is normally found.
The nests of Brunn are buds or sprouts of transitional epithe-
lium that grow from the surface into the underlying lamina
propria and may become centrally cavitated or cystic. The cells
Fig. 15.10 Normal squamous cells and urothelial cells
(Papanicolaou x MP).
lining the cystic spaces may remain flattened or low cuboidal
and resemble transitional cells, but others become columnar
and mucinous. These changes are considered to be reactive and
metaplastic. When the morphologic appearance is characterized
by the presence of mucin-secreting colonic-type epithelium, they
are referred to as cystitis glandularis or as intestinal or glandular
metaplasia. Many of the columnar cells often seen in urine are
cells from the intermediate zone of the transitional epithelium,
but they may exfoliate from metaplastic columnar or glandular
epithelium, from the urethra, and in males, after instrumenta-
tion or prostatic massage, from the prostate. Spontaneous exfo-
liation of prostatic columnar cells or of cells from the seminal
vesicles that may contain cytoplasmic pigment is rarely, if ever,
observed. The lacunae of Morgagni and glands of Littré are other
possible sites of origin. Most columnar cells are nonciliated, but
rarely, ciliated cells have been described in voided urine.17 They
may represent cells from the vasa deferentia or the epididymis,
structures lined by columnar cells with stereocilia, or they may
be the result of an unusual differentiation. The morphologic
appearance of columnar cells depends on their site of origin. If
benign, the nuclei are oval, uniform, or bland or have a finely
granular chromatin pattern (see Fig. 15.7).
Small numbers of polymorphonuclear leukocytes are often
present in normal urine. Histiocytes are found in inflammatory
conditions but, in small numbers, may be present in normal
urine. They have indistinct cell borders, a foamy cytoplasm, and
eccentric, lobed, or bean-shaped nuclei. They are often difficult
to differentiate from degenerated epithelial cells. Spermatozoa,
crystals (Fig. 15.11),
Trichomonas,
and lubricant (Fig. 15.12) may
also be seen.
Degenerative changes of exfoliated cells suspended in urine,
in the bladder, or after voiding do occur and may interfere with
interpretation. The urine osmolality ranges from 100 to more
than 1000 mOsm/L, with an average of 500, and is rarely in the
normal range for serum (275-300 mOsm/L). This suspension
in a usually hypertonic but sometimes hypotonic fluid should
be associated with degenerative changes in the cells, but exten-
sive quantitative studies did not demonstrate a relationship
between either cell size or degree of degenerative change and
the osmolality.14
413
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