Ductal Carcinoma
In Situ
359
FIG. 11.34.
DCIS, solid.
A:
The duct is filled by a compact growth of carcinoma cells with pleomor-
phic nuclei of intermediate nuclear grade.
B:
Solid apocrine DCIS with clear cell change.
FIG. 11.35.
DCIS, solid.
A:
Apocrine type of solid DCIS with loss of cohesion, with central necro-
sis (
inset
). The histopathologic appearance simulates pleomorphic LCIS.
B:
DCIS in
(A)
is strongly
E-cadherin positive, supporting ductal differentiation.
Some examples of
spindle cell DCIS
are variants of pap-
illary DCIS, but spindle cell growth can be encountered in
nonpapillary DCIS (Fig. 11.36).
Small cell DCIS
occurs in as-
sociation with invasive small cell (oat cell) carcinoma (see
Chapter 21) or as an isolated lesion (Fig. 11.37).
DCIS arising in SA
assumes the structural configuration
of the underlying adenosis and may be mistaken for invasive
carcinoma.
136–139
(Fig. 11.38). The majority of these patients
are premenopausal. Because SA is fundamentally a lesion
formed by altered lobules, this presentation can be viewed
as a form of intralobular extension of the ductal lesion. The
condition usually occurs focally rather than diffusely and is
diagnosed when the proliferative epithelium has the struc-
tural and cytologic appearance of DCIS. The growth patterns
are usually solid and cribriform (Figs. 11.38 and 11.39). An
organoid appearance may result from the alveolar expansion
of lobular structures in the adenosis. Microcalcifications
may be present in the underlying adenosis or as part of the
DCIS. DCIS can be limited to the SA, or there may be foci in
the surrounding breast.
137
The underlying architecture of SA can be appreciated with
stains for basement membranes such as PAS, reticulin, or lam-
inin, and immunostains to identify myoepithelial cells such as
p63, calponin, CD10, and SMA.
137,139
The antibody for SMM-
HC is useful in this circumstance because it is likely to avoid
most of the obscuring effect produced by actin reactivity in
myofibroblasts encountered with other antiactin antibodies
(Fig. 11.39). Rarely, invasive carcinoma can have an adenosis-
like pattern that is difficult to distinguish from DCIS in ad-
enosis. In this situation, stains for myoepithelium are useful.
Absence of myoepithelium is diagnostic of invasive carcinoma.
Invasive carcinoma arising in SA is difficult to detect un-
less the invasive component has clearly grown beyond the area
of adenosis and has an architectural pattern that differs from
that of the adenosis (Figs. 11.40 and 11.41). A double immu-
nostain for cytokeratin and actin can be helpful for identifying
