Fig. 25.26 Aspirates from breast hamartoma show similar cytologic
features of fibroadenoma. However, the presence of intact lobular units,
paucity of stroma fragments, and absence of large antler-horn cluster of
epithelial cells seen in aspirates of fibroadenoma may suggest the diagnosis
of hamartoma. (A, Diff-Quik x MP; B, H&E x MP).
subareolar area. The m am m og ram can reveal a mass w ith p o o rly
o u tlin e d borders th a t suggest a m a lig n a n t process. P leom orp hic
adenom a o f the breast shows cytologic features identical to its
m ore c om m o n salivary gland counterpart.206-211 The absence
o f b ip o la r naked nuclei and sp ind le cell strom al fragm ents are
h e lp fu l in d iffe re n tia ting th is e n tity fro m fib ro e p ith e lia l lesions.
However, the presence o f noncohesive e p ith elial cell clusters,
atypical isolated cells w ith h ig h N /C ratios, m ild p leo m o rp hism ,
and retic ular c hro m a tin w ith p ro m in e n t n uc le oli m ay lead to
false-positive diagnosis, such as m etaplastic carcinom a o r p hyl-
lodes tu m o r.206,207,211,212
Benign Lesions During Pregnancy and Postpartum
M o st breast lesions in pregnant and p ostp artum patients are
b enig n and are secondary to h o rm o n a l s tim u la tio n o f th e breast
tissue. Pregnancy produces de n ovo breast masses o r enlarges
preexisting breast masses, m o st o f w h ic h are fibroadenom as.
A lth o u g h m o st breast masses in pregnancy are benign, breast
carcinom a in a pregnant w o m a n needs to be excluded. M o st
de n ovo b enig n breast lesions associated w ith pregnancy usu-
a lly regress com p le te ly b y 6 m o n th s postp artum . FN A cytologic
find ing s o f lactating adenom as o r fib road enom as sho w ing lac-
ta tio n a l change generally p rod ucing a cell-rich sm ear p attern
c o n ta in in g a u n ifo rm p o p u la tio n o f e p ith e lia l cells, w h ic h
are u su a lly dispersed w ith occasional cell clusters.9,31,130,213-217
However, fib road enom as u nd erg oing la c ta tio n a l change in
pregnant w o m e n m ay be suspected w h e n a b ip hasic p attern
o f e p ith e lia l clusters and n um ero us b ip o la r naked nuclei are
appreciated in a d d itio n to th e la c ta tio n a l changes. In contrast,
de novo lactating adenom as have few o r n o b ip o la r nuclei
b u t con tain scattered stripp ed e p ith e lia l nuclei. B oth lactat-
ing adenom as and fib road enom as sho w ing la c ta tio n a l change
have a d irty background caused b y d isru p tio n o f th e delicate,
frayed pale cytoplasm and spillage o f th e secretory p rod uct
in to th e background caused b y th e tra um a o f sm earing the
slides. N u m e rou s stripp ed e p ith e lia l nuclei, m an y o f w h ic h
possess sm a ll n u c le o li, are present in th e secretory background
(Fig. 2 5 .2 8 ).31,130 T he secretory c om p on en t can also be d e m o n -
strated in air-d rie d smears w ith p eriod ic a c id -S c h iff (PAS) and
lip id staining.
Key features of lactating adenomas
• Cellular smears;
• Dispersed and poorly cohesive cell clusters;
• Epithelial cells with fragile, frayed granular to foamy to
vacuolated cytoplasm;
• Mildly enlarged, well-dispersed hyperchromatic nuclei
with prominent nucleoli;
• Numerous stripped epithelial (acinar) nuclei and few to
no bipolar naked nuclei are seen;
• Dirty background of cytoplasmic fragments and secretory
material; and
• Bipolar naked nuclei and stripped epithelial cells are seen
in fibroadenomas with lactational change.
O ccasionally, a false-positive diagnosis o f m alig nancy is pos-
sible due to th e p attern o f dissociated e p ith e lia l cells stripped
o f cytoplasm coupled w ith larger e p ith e lia l cells d e m onstrat-
ing nuclear a typ ic ality and p ro m in e n t n u c le o li (Fig. 2 5 .2 9 ).31 It
is especially im p o rta n t to appreciate th e presence o f cytoplas-
m ic secretion characterized b y cytoplasm ic foam iness o r vacu-
o la tio n w ith fraying o f cytoplasm ic borders in ord er to avoid
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