Fig. 25.5 Acute mastitis consisting of sheets of neutrophils
(Diff-Quik x HP),
Mammary Duct Ectasia (Plasma cell Mastitis,
Plasm a cell m astitis is a c o m m o n chronic in fla m m a to ry con-
d itio n o f the breast th a t m ay m im ic carcinom a b y sho w ing
n ip p le retra c tio n w ith an u n d e rlyin g w e ll-d efin ed , c en trally
located lesion. M am m o g rap h y m ay reveal calcifications. H is to -
logically, th e lesio n is characterized b y th e presence o f n u m e r-
ous lym p hocytes and plasm a cells surro u n d in g ducts fille d
w ith inspissated secretion in the acute phase. D u rin g th e heal-
ing stage o f the lesion, fib rosis and scar fo rm a tio n occur.24,130
T he aspirated m ate ria l is characteristically th ic k, creamy, and
hom ogenous. T he smears are characterized b y am orp hous
debris w ith variab le num bers o f fo a m y m acrophages and o th e r
in fla m m a to ry cells. O ccasionally, ductal cells m ay be present,
sho w ing a variab le degree o f in fla m m a to ry atypia. T he degree
o f atyp ia appears greater in th e R om anow sky-stained air-d ried
smears (i.e., D iff-Q u ik sta in ) th a n in P ap anicolaou-stained
alc oh ol-fixe d smears, o w in g to greater cell size in th e fo rm e r
type o f specim en. A p p rec ia tion o f th e in fla m m a to ry back-
g round in w h ic h th e atypia is present and a m ore conservative
cytologic in te rp re ta tio n based o n the find ing s in th e Papanico-
lao u-sta in ed smears serve as a check to avoid a false-positive
diagnosis o f m alignancy.
Subareolar Abscess
S ub areolar abscess is a specific c linico p atho lo g ic e n tity occur-
rin g in th e subareolar reg ion.131,141 It o fte n begins as a localized
area o f in fla m m a tio n beneath the n ip p le and th e n progresses to
fo rm an abscess, fo llo w e d b y subsequent cycles o f sinus tract fo r-
m a tio n , drainage, p artial healing, and recurrence (Fig. 2 5.7 ).131
W ith th e presence o f n ip p le retra c tio n and a mass, the lesion
can be c lin ic a lly confused w ith a neoplasm such as adenom a o f
th e n ip p le o r breast carcinom a. A spectrum o f c ytom orp h olog ic
Fig. 25.6 (A) Cluster of benign ductal cells showing atypical features
including prominent nucleoli, Note the neutrophils infiltrating the group
of epithelial cells (Papanicolaou x HP), (B) Atypical sheet of epithelial
cells showing features of regeneration and repair including nuclear
enlargement and prominent nucleoli (Papanicolaou x HP),
find ing s can be appreciated in the aspirate, in c lu d in g diagnos-
tic anucleated squam es associated w ith n um ero us n e u trop h ils,
kera tino us debris, cholesterol crystals, parakeratosis, and strips
o f squam ous e p ith e liu m ( Figs 25.7 and 2 5.8 ).130,131,142 A foreig n
b od y reaction w ith sheets o f histiocytes and m ultin u clea te d
foreig n b od y-typ e g iant cells can also be present (Fig. 2 5 .9 ).
Sub areolar abscess has also been reported in FN A o f the m ale
breast w ith s im ila r find ing s.143
Key features of subareolar abscess
• Anucleated squamous cells;
• Acute and chronic inflammation;
• Foreign body reaction or granulation tissue;
• Epithelial or mesenchymal repair; and
• Epithelial atypia a potential pitfall for false-positive
Subareolar abscess o f the breast dem onstrates som e o f the
p o ten tial diagnostic p itfa lls fo r a false-positive diagnosis o f
m alig nancy th a t can occur in any in fla m m a to ry process, in c lu d -
ing those in v o lv in g the breast. These features include groups
o f atypical ductal cells w ith in fla m m a to ry atypia o r repair
(Fig. 25.10), squam ous m etaplasia w ith atypia, and fragm ents
o f exuberant g ra n u la tio n tissue (Fig. 25.11).131,143,144 A rup tured
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