Diagnostic Cytology
Fig. 25.55 (A) Aspirate from micropapillary carcinoma shows moderate cellularity with multipe tightly cohesive tumor clusters (Papanicolaou x MP).
(B and C) The tumor clusters show angulated/scalloped borders and moderate nuclear pleomorphism (Papanicolaou x HP).
inflammatory Carcinoma
In fla m m a to ry carcinom a is an u n c o m m o n , aggressive fo rm o f
breast carcinom a accounting fo r ap p roxim ately 2 -4 % o f cases.
C lin ica lly, the breast appears hyperem ic, engorged, and edem a-
tous, w ith peau d'orange skin changes and histo p atho lo g ic fin d -
ings o f m a lig n a n t cells w ith in the lym p hatics o f the overlying
skin and breast parenchym a. Because th is lesion u su ally does n o t
fo rm a discrete palpable mass, it is n o t as am enable to diagnosis
b y FN A as o th e r breast lesions. A sp ira tio n o f the derm is, subcu-
taneous tissue, o r und e rlyin g breast tissue w ith m u ltip le passes
m ay be required to o b tain diagnostic m aterial. Aspirates are usu-
a lly paucicellular and m a lig n a n t cells are p re d o m in a n tly d istrib -
uted in tig ht, th ree-d im ensional clusters. T u m o r cells show large
size, nuclear irregularity, and increased N /C ratios. U n lik e aspi-
rates fro m conventional breast carcinom a, in d ivid u a l dispersed
cells and cellular dyscohesiveness are n o t p ro m in e n t features.341
A tissue b iop sy is occasionally needed fo r c on firm a tio n .
Paget's Disease
Paget's disease presents w ith an eczem a-like change o f th e
n ip p le and areola, occ asion ally associated w ith an u n d e rly -
ing breast mass. C yto lo g ic diagnosis can be m ade b y scraping
th e n ip p le o r b y F N A biopsy. T u m o r cells are arranged in d i-
v id u a lly and in clusters (Fig. 2 5 .6 0 ). D iffe re n tia tio n fro m
m a lig n a n t m e la n o m a can be enhanced w ith th e use o f an
im m u n o c y to c h e m ic a l panel, w h ic h d em onstrates p o sitive
sta in in g o f m a lig n a n t cells in Paget's disease fo r ER, CEA,
e p ith e lia l m em b rane antigen, and c yto ke ra tin , versus cyto-
p lasm ic s ta in in g fo r S-100 p ro te in o r H M B -4 5 in m a lig n a n t
m elan om a.
Metaplastic Carcinoma
M etaplastic carcinom a is a heterogeneous group o f breast
m alignancies characterized b y a m ix tu re o f carcinom a w ith
areas o f spindle, squam ous, chond roid , o r osseous m etapla-
sia.30,342,343 M etaplastic carcinom as are q u ite unu su a l, account-
ing fo r o n ly 0.2% o f breast m alignancies.343 T he average age o f
patients is over 50 years old , s im ila r to classic in filtra tin g ductal
carcinom a. M etaplastic carcinom a can also be seen in im m u n o -
com p rom ised patients such as h u m a n im m u n o d e fic ie n c y virus
and renal tra nsp lan t p atients.344,345 Carcinosarcom a va ria n t o f
m etaplastic carcinom a has the w o rst prognosis. M etaplastic
carcinom a can present as a large cystic le sio n .346,347 T he cyto-
logic diagnosis o f m etaplastic carcinom a is u su a lly challeng-
ing. However, th e m ixed p o p u la tio n o f m a lig n a n t ductal cells,
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