900
Chapter 33
women treated by mastectomy, carcinoma was limited to the
FA in one-third to one-half of cases that had LCIS, DCIS, or
ILC.
101,104
IDC that arose in a FA involved the surrounding
breast tissue in at least 50% of cases. With rare exceptions,
the same type of carcinoma has been found in the FA and in
the breast tissue. LCIS may be detected in multiple FA in one
breast or in bilateral FA.
100
ALNmetastases have arisen from
invasive carcinoma present
exclusively
within a FA in two
cases.
97,112
Ten percent to 15% of patients with carcinoma in
a FA have had contralateral carcinomas concurrently or pre
viously treated.
96,100,101
The opposite breast contained IDC in
the majority of these cases. Subsequent contralateral carci
noma has been described in about 6% of cases.
99
Phyllodes Tumor
Florid hyperplasia involving epithelial and myoepithelial
cells is often encountered in PT. The degree of atypia in the
epithelial hyperplasia parallels that of the stromal compo
nent in some but not all cases. Mitoses may be seen in hyper
plastic epithelial and myoepithelial cells.
Carcinomas arising in PT are histologically similar
to carcinomas developing in FA. LCIS (Fig. 33.7) is less
breast tissue in about half of the cases. Nearly 20% had DCIS
(Figs. 33.3 and 33.4). IDC accounted for 20% of the cases
(Fig. 33.5), and about 10% had invasive lobular carcinoma
(ILC) (Fig. 33.6). The IDCs have well-differentiated to mod
erately differentiated lesions. It is exceedingly unusual for
special types of duct carcinoma to arise in a FA or PT. Atypi
cal epithelial lesions in fibroepithelial tumors are prone to
having a conspicuous myoepithelial component, and are
associated with a variety of findings, including sclerosing
adenosis (SA), cysts, apocrine metaplasia, and calcifica
tions, which constitute the so-called complex FA. Petersson
et al.
111
described a complex FA that gave rise to a low-grade
in situ
and invasive ductal carcinoma (IDC) associated with
columnar cell change.
The probability of finding carcinoma in breast tissue out
side a FA that is involved by carcinoma has been difficult to
determine on the basis of published reports, because many
patients were treated only by excisional biopsy. A literature
review of 62 published cases found extra-fibroadenomatous
carcinoma in 42% of patients.
104
Diaz et al.
99
reported that
the type and amount of carcinoma in a FA and the age at
diagnosis were not significant predictors of the likelihood of
finding carcinoma in the surrounding breast tissue. Among
FIG. 33.3.
Fibroadenoma, intraductal carcinoma.
A:
Crib-
riform growth pattern.
B:
Apocrine cytology.
C:
Cribriform
and solid types of DCIS involving a FA and glands within
its vicinity.
C
