28
Liver and Pancreas
Fig. 28.92 Pleomorphic giant cell carcinoma of the pancreas.
A multinucleated giant tumor cell that has several pleomorphic nuclei and
prominent nucleoli surrounded by mononucleated tumor cells. FNA smear
(Papanicolaou x HP).
Fig. 28.93 Adenosquamous carcinoma of the pancreas.
Keratinized squamous cells intermixed with glandular cells. FNA smear
(Papanicolaou x MP).
Key features of pleomorphic giant cell carcinoma
of pancreas
• N u m e ro u s sin g le p le o m o rp h ic cells w ith p ro m in e n t
n u c le o li, m o n o n u c le a te d o r m u ltin u c le a te d ; and
• C lin ic a l p re s e n ta tio n a nd c y to k e ra tin exp ression can
exclude o th e r p o ssib ilitie s.
Adenosquamous carcinoma
Adenosquamous carcinomas may develop in many organs. The
pancreas is one of the more common sites for the occurrence
of adenosquamous carcinoma. Adenosquamous carcinomas
constitute about 3-4% of exocrine pancreatic neoplasms. They
probably arise from squamous metaplasia of the terminal ducts.
Pure squamous cell carcinomas of the pancreas are very rare. As
shown in Figs 28.93 and 28.94, the aspirates of adenosquamous
carcinomas show a dual population: adenocarcinoma cells with
evidence of secretory activity and squamous carcinoma cells
showing keratinization.134-136
Fig. 28.94 Adenosquamous carcinoma of the pancreas. Characteristic
histology seen in cell block processed from fine-needle aspirate (H&E x MP).
Ampullary carcinoma
Carcinomas are much less frequent in the periampullary region
than in the pancreas. Because obstruction of the bile duct by the
tumor causes early onset of jaundice, ampullary carcinomas are
often discovered at an early stage of the disease and are usually
much more curable than carcinomas of the head of the pan-
creas. Most ampullary carcinomas are adenocarcinomas, many
of them having a superficial papillary component.137
Cytology
In FNA smears, the cytologic features are those of well-
differentiated adenocarcinoma of the pancreas arising from the
pancreatic ducts.138 The differential diagnosis can be based only on
clinical and radiographic findings. In advanced disease, with the
invasion of adjacent structures and the head of the pancreas, it is
often impossible to ascertain the source of the adenocarcinoma.
Pancreatic Endocrine Tumors
Tumors of endocrine pancreas arise from amine precursor uptake
and decarboxylase (APUD) pleuripotential stem cells139 located
within the ductal epithelium of the exocrine pancreas rather
than directly from islet cells as previously assumed.140 The fact
that many gastrinomas and somatostatinomas are found close to
but not within the pancreas supports the notion of APUD stem
cells, which are located also in the distal foregut.141 In 1995, the
term
islet cell tumors
was replaced by
pancreatic endocrine tumors
in the revised classification of neuroendocrine tumors of lung,
pancreas, and gut.142 In 1998, APUD cells were found to develop
from the embryologic endoderm143 rather than neural crest as
commonly believed since 1968.139
Pancreatic endocrine tumors make up less than 5% of all
pancreatic neoplasms and most commonly are located in the
907
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