대한혜담도연구회지 1997; 2: 168-172

Adenosquamous Carcinoma of the Pancreas: Differentiation from Pancreatic Pseudocyst

Seung Jae Myung, M.D. , Yeun Suk Kim, M .D ., Seung Yong Kim, M .D.

=국문초록=

Hong Ja Kim, M.D. , Jeong Su Kim, M.D., Dong Wan Seo, M .D .,

Sung Koo Lee, M.D. , Myung Hwan Kim, M.D., and Young 11 Min, M.D.

Department of Intemal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

가성낭종과 구별이 어려웠던 훼장 선편평상피암 1여|

울산대학교 의과대학 서울중앙병원 내과학교실

명승재·김연석·김승용·김흥자·김정수

서동완·이성구·김명환·민영일

혜장의 선평편상피암은 드문 형태의 춰l장암으로 이의 생물학적 행태와 임상적 양상은 훨씬

흔한 종류인 쉐장선암입니다 선암이나 순수한 평편상피암과 유사한 것으로 알려지고 있다. 저자등은 초기에 쉐장가성낭종과의 감별이 힘들었던 드문 형태의 춰l장 선편펑상피암 1예를

경험하였기에 문헌고찰과 함께 보고하는 바이다.

중심단어 선편평상피암， 춰l장， 궤장가성냥종， 낭성변성

extravasation of contrast to the mass have also been

INTRODUCTION reported.5-6 We report here an unusual case of adeno­

squamous carcinoma of the pancreas which has ini-

Adenosquamous carcinoma of the pancreas is a rare tially brought some difficulties in differentiating from

form of pancreatic cancer. 1•2 Its bi이ogical behavior pancreatic pseudocyst.

and c\inical features are known to be similar to the

much more common ductal adenocarcinoma or to

pure squamous cell carcinoma, another rare form of

pancreatic malignancy.3.4 However, the unusual mani­

festations of cancer with cystic degeneration and

연락처 명송재， 서울시 송파구 풍납동 388-1 , 서울중앙병원 소화기 내과

168

CASE REPORT

A 64-year-old man was admitted to our hospital

with a two-week history of epigastric pain. The

patient complained that the pain was dull and

continuous radiating to his back. He was a social

Seung Jae Myung, et al: Aden∞quamous Carcinoma of the Pancreas: Differentiation from Pancreatic Pseudocyst 169

drinker and denied use of any kind of drug medi- mild tenderness over the epigastrium, but no rebound

cation. There was no history of abdominal trauma or tenderness or guarding was present. There was no

diabetes mellitus. No fever, chills, jaundice, or weight hepatosplenomegaly or palpable mass. Laboratory

loss was reported. Family histoη was unremarkable. tests incIuded white blood count 8,100 cellsjmm3, On physical examination, the patient was thin and hemoglobin 13.6 gjdl, amylase 263 UjL (60-210 UjL) ,

not in the state of acute distress. He complained of and Iipase 461 UjL (66-220 UjL). Liver function test

and tumor markers (CAI9-9 and CEA) were within

Fig. 1. Abdominal CT scan showing 3- to 4-cm sized ovoid cyst-like lesion in the region of the pan-creatic head.

the norrnal Iimit.

An abdominal CT scan revealed a 3- to 4-cm sized

ovoid and cyst-Iike lesion in the region of the pan­

creatic head (Fig. 1). The pancreatic duct was mildly

dilated, however, the parenchyma of the pancreatic

body and tail showed no specific abnorrnal findings.

Endoscopic retrograde balloon pancreatography (ERP)

showed about a 2 cm segmental narrowing of the

main duct at the head portion of the pancreas and

mild upsπeam dilatation (Fig. 2A). In the pancreatic

head, round contrast pooling in communication with

the main duct was noted (Fig. 2A). Brush cytology

revealed no malignant cells but many sheets of ductal

Fig 2. A. Endoscopic retrograde balloon pancreatogram (ERP) showing segmental narrowing (arrow) and mild up­stream dilatation of the main pancreatic duct and round pooling of the contrast at some distance (arrow head).

B. Magnetic resonance cholangiopancreatography revealing pancreatic ductal change similar to the find­ings on ERP and round cystic lesion in the pancreatic head.

170 대한혜담도연구회지 제 2 권 제 2 호 1997

epithelial cells. Magnetic resonance cholangiopancrea­

tography showed pancreatic ductal change similar to

the findings on ERP and a round lesion with cystic

character in the pancreatic head (Fig. 2B).

The clinical features and radiological fmdings were

felt most consistent with a pancreatic pseudocyst and

benign stricture secondary to chronic pancreatitis, although a cystic tumor or ductal carcinoma could not

be ruled out. A pancreatic stent was inserted to relieve

the stasis in the pancreatic duct, and supportive care

including NPO and total parenteral nutrition was com­

menced. Even after four weeks of medical therapy,

the patient still complained about the persistence of

abdominal pain. Follow-up ERP showed no change of

the ductal narrowing in the main pancreatic duct but

the cyst-like lesion in the region of the pancreatic

head showed enlargement on follow-up CT scan.

Cytologic findings from needle biopsy of the pan­

creatic head were interpreted as adenosquamous carci­

noma.6•7 The patient underwent pylorus preserving

pancreatoduodenectomy and a 3.5 x 3 X 2.8 cm sized

poorly demarcated mass with a cystic cavity was

resected (Fig. 3). Upon histological examination, the

tumor was composed mainly of nests of malignant

squamous cells with areas of adenocarcinoma which

was compatible with adenosquamous carcinoma of the

pancreas (Fig. 4) πle postoperative course was un-

Fig 3. Macroscopic appearance of the adenosquamous carcinoma of the pancreatic head. Poorly de­marcated firm infiltrating mass with cystic change was noted

Fig 4. Photomicrograph of the transitional zone where adenocarcinoma and squamous cell carci­noma are seen m contact.

Seung Jae Myung, et al: Aden∞quamαIS Carcinαna of the Pancreas: Differentiation from p，외1σ'eatic Pseudocyst 171

eventful and the patient was doing well at 4-month creatic duct. Pain relief and the resolution of the

follow up. pseudocyst were expected. lO,11 Even after four weeks

of medical treatment, the patient ’s symptoms had not

DISCUSSION been improved. Follow up ERP showed no change of

Adenosquamous carcinoma of the pancreas, often

called adenoacanthoma, is a rare variant of nonendo­

crine pancreatic cancer. 1,2 까le collective incidence of

this malignancy has been estimated at 1 - 4 % of

pancreatic malignancies,3-4,8 even though higher rates 1,9 of 9-11 % have been reported in Japan.'" Some au-

thors have suggested that pure squamous cell carcino

ma behaves more aggressively,8 however, literature

review shows no significant differences in age pre­

valence, sex ratio, distribution of cancer in the pan­

creas, neoplastic behavior, or prognosis among adeno­

squamous carcinoma, ductal cell carcinoma, and pure 2-5 squamous cell carcinoma of the pancreas.

Our patient was initially managed under the diag­

nosis of chronic pancreatitis with pseudocyst because

of his pain compatible with pancreatitis and the ele-

vated pancreatic enzymes. Radiologic fmdings sup­

ported our first conclusion. Segmental narrowing of

the main pancreatic duct suggesting benign stricture

was detected on ERP. The lesion in the pancreatic

head was almost purely cystic and it did not exhibit

a definite mass on CT (Fig. 1). Brush cytology

revealed no malignant cells, a1though a sufficient

number of cells had been taken. However, there also

were several fmdings that were not consistent with

chronic pancreatitis. The parenchyma of the pancrea­

tic body and tail did not show the changes of chronic

inflammation, such as swelling, fluid collection, or

calcification on CT scan. The dilated main duct was

rather smooth on ERP as well . A cystic tumor and

malignant neoplasm were also suspected, but clinical

features and radiological findings were not compatible

with both conditions.

The patient was managed by stenting of the pan-

ductal stricture, and abdominal CT scan showed

enIargement of the previously noted cyst-like lesion.

πle cytologic findings from the needle biopsy sug­

gested adenosquamous carcinoma of the pancreas,

which was confirmed by surgical resection of the

tumor.

Aside from having a rare type of pancreatic tumor,

this patient exhibited very unusual features which led

us to an erroneous initial diagnosis. This case showed

extravasation of ERP contrast into a tumor cavity due

to cystic change, as well as ductal communication to

the cystic portion of the tumor. These findings can

occur in a cystic neoplasm with ductal communication

or in a pseudocyst associated with pancreatitis or

tumor. Extravasation of the contrast to the ductal cell

carcinoma is possible,12 however, pooling of the

contrast at some distance from the main duct or round

accumulation of the contrast shown in our case is an

uncommon finding. πlese findings are quite unusual

for adenosquamous carcinoma of the pancreas as well, 5,6 although a few similar cases had been reported. J ,U Our

case and previous cases suggest that this rare pan­

creatic malignancy can be misdiagnosed as pancrea­

titis with pseudocyst. In adenosquamous carcinoma of

the pancreas, ductal communication with cancer may

be expected since this rare malignancy may arise from

the malignant degeneration of squamous metaplasia of

pancreatic ductal epithelium.1

In summary, we report a case of adenosquamous

carcinoma of the pancreas with unusual manifestation.

lnitially, a cyst-like lesion in the region of pancreatic

head was diagnosed as pancreatic pseudocyst asso­

ciated with chronic pancreatitis. Our case emphasizes

that this rare pancreatic tumor can be difficult to

differentiate from a benign condition, such as pan-

172 대한쉐담도연구회지 · 제 2 권 제 2 호 1997

creatic pseudocyst, thus mislead the physician into

arriving at an initial misdiagnosis.

Key Word: Pseudocyst, Pancreas, Adenosquamous

carcmoma

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