Liver and Pancreas
are lin e d b y ta ll colum na r cells w ith basal nuclei and abundant
intracytoplasm ic apical m uc in in fla t sheets o r papillae, freq uently
w ith ovarian-type strom a. M ucinous cystic neoplasm s are clas-
sified as adenom a, borderline, carcinom a in situ, and invasive
based on the severity o f the dysplasia o f the lin in g e p ith elium o r
the presence o f strom al invasion. A p p roxim a te ly o ne -third are
associated w ith invasive ductal carcinom a. The cavities contain
m ucous m aterial and are lin e d b y ta ll, m ucin-producing epithe-
lia l cells (Fig. 28.72) .101-105 A lth o u g h benign and m alig n an t varie-
ties exist, the d istin ctio n between benign and m alig n an t tum ors
is n o t always clear-cut and requires extensive sam pling o f the
tum or. Therefore all these m ucinous tum ors should be regarded
as p o te n tia lly m alignant. Cases o f "m uc in o us cystadenom a"
recurring as cystadenocarcinom a are w e ll docum ented. Therefore
to ta l excision o f the tu m o rs is strong ly recom m ended.
The aspirates usually are h ig h ly cellular in a m ucinous background,
best seen in Rom anow sky stain (Fig. 28.73) . The cytologic smears
m ade fro m aspirated m ucous m aterial show num erous epithelial
cells w ith vacuolated cytoplasm , resem bling benign cells fro m the
endocervix.106,107 The tu m o r cells occur in p ap illary (Fig. 28.74)
o r sheet arrangements w ith a honeycom b pattern (Fig. 28.75) or
singly, often appearing as goblet cells. The nuclei are ro u n d or
ovoid and m ay have sm all nucleoli. In the b ord erline neoplasms,
carcinom a in situ o r m ucinous cystadenocarcinomas, atypical epi-
th elia l cells are a com m on finding . They are larger, and the nucle-
ocytoplasm ic ratio is higher. T h e ir nuclei often show variations in
size and have conspicuous nucleoli and fin e ly granular o r slig htly
coarse chrom atin. In som e cases, atypical ep ithelial cells show ing
m alig nant tra nsform ation are noticed. These h ig h ly abnorm al
cells th a t have large nuclei w ith variations in size and shape and
slig htly coarse chrom atin occur in disorderly arrangements.
Key features of mucinous cystic tumors
• C lin ic a l: p re d o m in a n tly m id d le-a g ed w o m e n , occasional
m en.
• C T scan: th ic k -w a lle d m u ltilo c u la te d cystic mass w ith o u t
c o n n e c tio n to th e ductal system a t th e ta il o f th e b o d y o f
th e pancreas.
Fig. 28.72 Mucinous cystic tumor of the pancreas. Fragments of
mucinous columnar epithelium with intracytoplasmic mucin and basally
located nuclei. Cell block (H&E x MP).
• A b u n d a n t m u c in c o n ta in in g p a p illa ry fra g m e nts o f e p ith e -
liu m .
• C o lu m n a r cells w ith b la n d o va l n u c le i w ith fin e c h ro m a tin
a nd w ith tin y n u c le o li.
intraductal Papillary Mucinous Neoplasm
Intrad uctal p a p illa ry m ucinous neoplasm s are a d istinct group
o f pancreatic tu m o r.108 T hey occur m ore o fte n in elderly m en in
th e ir seventies and eighties.109 T hey involve the m a in pancreatic
duct and m a jo r branches. T he tu m o rs secrete copious am ounts
o f m ucin, leading to ductal d ila ta tio n and fre q ue ntly o ozing o u t
fro m the a m p u lla o fV a te r seen endoscopically.110-112 CT scans w ill
typ ic a lly show a lob u la te d m u ltilo c u la r cystic lesio n located in
the uncinate process and in c o n tig u ity w ith the dilated m a in pan-
creatic duct.113 In som e patients, a b ulg ing p a p illa and p ap illary
Fig. 28.73 Mucinous cystic tumor of the pancreas. Abundant mucin
containing papillary fragments of epithelium. FNA smear (Romanowsky x LP).
Fig. 28.74 Mucinous cystic tumor of the pancreas. Neoplastic
epithelium in complicated papillary arrangement. FNA smear
(Papanicolaou x MP).
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