Fig. 25.8 (A) Parakeratosis and acute inflammation in the aspirate of a subareolar abscess (Papanicolaou x LP). (B) Fine-needle aspiration of subareolar
abscess revealing diagnostic anucleated squames and associated acute inflammation (Diff-Quik x HP). (C) Squamous metaplasia of lactiferous duct
with overlying anucleated squames and keratinous debris and surrounding chronic inflammation (H&E x LP).
epiderm al in c lu sio n cyst arising in the skin overlying the breast
shares s im ila r cytologic and histo lo g ic features w ith subareolar
abscess, b u t the peripheral loc a tio n o f the epiderm al in c lu -
sion cyst sho uld clearly d isting uish th is lesio n fro m the cen-
tra l subareolar abscess. Subareolar abscess m ost lik e ly arises
fro m squam ous m etaplasia o f the e p ith e liu m o f the lactifer-
ous duct; the lu m e n o f the duct fills w ith keratinous debris and
th en ruptures (Figs 25.7 and 25.8). A surro un d in g in fla m m a -
to ry cell reaction occurs, inc lu d in g a foreig n b od y reaction to
keratinous-type debris (Fig. 2 5.9 ). T he correct diagnosis o f this
e n tity is crucial fo r the patient's m anagem ent because chronic
subareolar abscess u su a lly requires com plete surgical excision
o f the affected duct.131,142
Adipose tissue is c o m m o n ly fo u n d in breast aspirates as a com -
p o ne nt o f n o rm a l breast tissue. T he presence o f fa t in the smears
is u su ally as a result o f inadequate sam p ling o f a palpable mass,
representing inad vertent asp iration o f the surro un d in g n o n -
diagnostic adipose tissue (Fig. 2 5.1 2 ). Therefore the diagnosis
o f a breast lip o m a can be suggested o n ly i f there is strong
m am m og rap hic correlation. T he confidence level o f m aking
the diagnosis o f lip o m a is enhanced w ith m u ltip le sam p ling o f
the lesion b y the aspirator w h o is the same in d ivid u a l inte rp ret-
ing the cytologic m aterial, and the clinical and m am m og rap hic
finding s sup p ort the diagnosis.
Fat Necrosis
Fat necrosis occurs after traum a, foreig n b od y reaction, o r a
response to a breast m alig nancy o r radiotherapy, especially if
tu m o r necrosis is present. Fat necrosis can radiologically, grossly,
and h isto lo g ic a lly (especially at frozen section) m im ic m alig -
nancy. T he FN A o f fa t necrosis consists o f fat; am orp hous debris
(degenerating fa t); in fla m m a to ry cells inc lu d in g neutrop hils,
plasm a cells, and lym phocytes; and num erous lip id -la d en m ac-
rophages (lipophages). The lipophages have abund ant vacu-
olated cytoplasm (Fig. 25.1 3 ). M u ltin u clea te d macrophages and
spindle-shaped fib rob lastic cells can also be present. The rare
h ib e rn o m a o f the breast sho uld be considered in the d iffe re n tia l
diagnosis w h e n fin e ly and coarsely vacuolated cells are encoun-
tered. M yospherulosis, a possible sequela o f fa t necrosis, has
been reported in FN A m a te ria l.145 Spherules m easuring 4 -7 pm
each and arranged in d iv id u a lly o r in sac-like structures are
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