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Figure 37. Patterns of islet cell tumors in hamster. a) Cystic islet cell adenoma, X 32. b) cystic-hemorrhagic
islet cell adenoma, X 32. c) Partial replacement of islet cells by large pleomorphic cells, X 65. d) Islet cell
tumor with sarcoma-like pattern and apparent minimal invasion (top), X 65.
been produced by intravenous inoculations of BK
virus to 22-day-old Syrian golden hamsters 137 .
In all hamster strains, the latency of spontaneous
islet cell tumors is long but generally shorter in
females (80 to 90 weeks) than in males (over 100
weeks). Islet cell carcinomas generally occur, but
not as a rule, in older animals. Under
experimental conditions, however, these
neoplasms develop as early as six months of
age 137, 138 .
Islet cell carcinomas are usually locally invasive
and occasionally metastasize into the regional
lymph nodes and liver. We observed splenic vein
thrombosis in the immediate proximity of a large
islet cell carcinoma. Virus-induced islet cell
carcinomas metastasized more frequently (44%)
and primarily into the liver 137, 138 .
6a. Comparative spontaneous pancreatic
diseases
To evaluate and compare the rate, extend and
types of pancreatic lesions that occur naturally in
hamsters and humans, we examined the
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pancreas of 83 military veterans aged 35-88 years
soon after autopsy by serial or step sectioning of
tissues 141 . Two patients had clinically known
primary and three secondary (metastatic)
pancreatic cancer. Hyperplasia of the ductal and
ductular epithelium was found in 57% and 39%,
respectively, squamous cell metaplasia of the
ductules in 48%, islet cell adenoma in 10%, and
mixed ductular-insular adenoma in 3% of the
cases. Peri-insular and intra-insular ductules,
similar to those seen in hamsters, were noted in
areas of acinar cell atrophy. A microscopic (early)
adenocarcinoma and adenosquamous cell
carcinoma were found in two cases, one ductal
carcinoma in situ and seven foci of atypical
ductular proliferation, three of which had
pancreatic cancer and the remaining four had
cancer of other sites (ethmoid, ear, colon,
prostate). A patient with lung cancer was found to
have a primary pancreatic cancer with metastases
into the lung. Hence the incidence of
“spontaneous” malignant lesions of the pancreas
in this series was 10%.