BREAST CYTOPATHOLOGY

Breast Ductal Lavage 155
undiagnosed carcinoma, but the number of DL cases with
abnormal cytology (mild and marked atypia) was more than
fourfold higher than for NAF (see Table 6.2). Some investigators
have proposed the use of DL for breast cancer risk
assessment, but no data are available at present to guide the
clinical application of this novel technique.
For historical reasons, micropore filter preparations of DL
(and NAF) samples were obtained in the feasibility study, but
liquid-based preparations and cytospin slides can also be
used. In the feasibility study, only 10 epithelial cells per duct
were required for a satisfactory DL specimen, to allow correlation
with prior results. Because DL yields at least 10-fold
more epithelial cells than NAF, a higher number of cells
should be required for a satisfactory DL sample. Nonetheless,
even the presence of abundant epithelium does not guarantee
that a DL sample will be representative of the alterations in
the duct.
The criteria used for evaluation of DL cytology are similar
to those used for breast FNA. Direct comparison of DL and
FNA samples obtained from the same cases of carcinoma
underscores the morphologic similarities between the two
types of sample. Cell arrangement, cell size, nuclear size and
size variation, nuclear membrane irregularity, chromatin
granularity, and presence of large nucleoli are the cytologic
features most helpful in the identification of abnormal epithelial
cells in DL samples.
Benign ductal cells (Figures 6.1 to 6.3) are usually present
in flat sheets and clusters of less than three cell layers. They
are small and uniform in size, with rare and small nucleoli.
Myoepithelium is present admixed with the benign ductal
cells.
In atypical ductal cells (Figures 6.4 to 6.10), mild atypia is
defined by the presence of ductal cells with slight nuclear
enlargement. The epithelium is organized in monolayers,
small clusters, and single cells. The nuclear membrane is
smooth, the nuclear chromatin is finely granular, and small
nucleoli are present.
Ductal cells with marked atypia can be present singly, in
monolayers, or in small clusters; large clusters of more than