PART TWO
Diagnostic Cytology
Fig. 25.21 Aspirate from a fibroadenoma showing tightly cohesive groups
of ductal cells having a branching pattern along with loose stroma and some
bipolar naked nuclei (Papanicolaou x LP).
■ -m
Fig. 25.22 (A and B) Large antler-horn cluster of epithelial cells seen in
aspirate of a fibroadenoma (Papanicolaou x LP).
Key features of fibroadenomas
• Moderate to high cellularity;
• Sheets of cohesive epithelial cells;
• Branching antler-horn or finger-like projections of
epithelial cells;
• Numerous bipolar (naked) nuclei;
Fig. 25.23 Aspirate from a fibroadenoma showing fragments of stroma
and cluster of ductal cells with nearby naked nuclei (Papanicolaou x LP).
• Stromal fragments; occasional myxoid change seen;
• Few or no foam cells or apocrine cells;
• Freely movable circumscribed discrete mass in contrast
to ill-defined, indurated lesion of fibrocystic change (help-
ful clinical feature); and
• Hypercellularity or ductal atypia can be a potential source
of false-positive diagnosis.
The cytologic features o f fib road enom a cannot always be
distinguished fro m those o f fibrocystic disease.81,130 Bottles and
associates, using stepwise logistic regression analysis, d em on-
strated th a t strom al fragments, a ntler-h orn clusters, and m arked
cellularity were the three m ost useful cytologic variables to dis-
ting u ish fib road enom a fro m fibrocystic disease (Fig. 25.23).169 A
separate analysis dem onstrated th a t honeycom b sheets, antler-
h o rn clusters, and strom a were the m ost useful features in d istin -
guishing fib road enom a fro m ductal carcinom a.169 D e jm e k and
L in d h o lm applied Bottles and coworkers' criteria to th e ir series
o f fibroadenom as and noted th a t strom al fragm ents were fo u n d
in o n ly 57% o f the cases, antler-h orn clusters in 90% , and h o n -
eycomb sheets in 81% .170 They also com m ented th a t very rarely
carcinom a can arise in a fibroadenom a, thus careful screening
fo r m alig n an t cells is required in th is setting. Conversely, Stanley
and colleagues reported th a t FN A o f fibroadenom as w ith atypia
could cytologically m im ic carcinom a.34 They concluded, based
on histolog ic e xa m in ation o f the excised fib road enom a after
FN A biopsy, th a t the atypia was due to m u ltifa c to ria l causes,
includ ing h o rm o n a l s tim u la tio n ,
in fla m m a tio n ,
m etaplastic
changes, and preneoplastic atypia. They cautioned th a t carci-
nom a should be diagnosed o nly w h en m u ltip le cytologic crite-
ria o f m alignancy are appreciated. The p otential also exists fo r
a false-positive diagnosis o f m alignancy in aspirates fro m som e
cases o f fibroadenom a, ow ing to the hypercellularity, loose cohe-
sion o f the cell groupings w ith som e anisonucleosis and p ro m i-
n ent nucleoli o f the cells (Fig. 25.24).89,171,172 The presence o f
fing er-like projections (an tler-like clusters) and b ip o la r naked
nuclei in the background should suggest the correct diagnosis o f
fib road enom a.130,173 O th er changes th a t can be seen in fib road -
enom a include m yxoid degeneration o f the strom a, foam cells,
apocrine m etaplasia, squam ous m etaplasia, single cells w ith cyto-
plasm , and m ito tic figures (Fig. 25.25). Fibrosis a n d /o r strom al
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