mucoepidermoid carcinoma was first described as a separate entity in 1945 by stewart et al . and is most commonly found in the salivary gland[24 ] bronchi,[59 ] and liver .
a total of seven cases have been reported , and we report herein the eighth case and review the literature on the previous cases .
a 63-year - old woman was admitted to our hospital , following a 5-year history of left upper abdominal pain and abdominal distension ( the second affiliated hospital , school of medicine , zhejiang university , hangzhou , china , 2011 ) .
computed tomography ( ct ) scan performed by a local physician 1 week before admission revealed suspected pancreatic cancer .
she was then referred to our hospital for further examination and treatment . at the time of admission
, she complained of loss of appetite and nausea , but no jaundice was found .
the serum levels of carbohydrate antigen 19 - 9 ( ca19 - 9 ) was elevated at 500.1u / ml ( with normal range less than 37 u / ml ) .
the serum level of carcinoembryonic antigen ( cea ) , squamous cell carcinoma antigen , alpha - fetoproteins , and neuron - specific enolase were not elevated .
computed tomography scan revealed a solid mass , approximately 4.5 cm in diameter , located at the left upper abdomen .
the tumor was irregular in shape , and appeared to arise from the distal pancreas [ figure 1a ] .
the tumor was irregular in shape , and appeared to arise from the distal pancreas.(b)a splenic artery aneurysm existed near celiac trunk a laparotomy was performed and we found that the tumor arised from the pancreatic body and tail without breaking pancreatic capsule
the distal pancreas , spleen , and its aneurysm were resected [ figures 2a and 2b ] .
( a ) the specimen removed from the pancreas , the tumor arised from the distal pancreas without breaking pancreatic capsule .
( b ) the specimen of the 
 splenic artery aneurysm was near celiac trunk on pathologic examination , the size and the cut surface showed a milky - white solid and homogeneous tumor with a hard elastic consistency .
the tumor consisted of three types of cells , the majority being poorly differentiated adenocarcinoma cells with mucin products in their cytoplasm , and some moderately differentiated adenocarcinoma with a tendency to form ducts .
these epidermoid cells did not have definite intercellular bridges , keratohyaline , or keratin pearls .
no differentiated squamous carcinoma cells were detected in any part of the tumor [ figure 3 ] .
( h and e , 100 ) the tumor consisted of three types of cells , the majority being poorly differentiated adenocarcinoma cells with mucin products in their cytoplasm , and some moderately differentiated adenocarcinoma with a tendency to form ducts .
in addition , there were epidermoid cells and intermediate undifferentiated cells the cells of the tumor showed strong staining with antibodies to ck7 , ck5/6 , and cea , showed negative staining for ck20 , the proliferation index by ki-67 stain was above 30% .
the postoperative course was uneventful and the patient was discharged 2 weeks after the surgery .
gemcitabine was used once but the patient had severe gastrointestinal side - effects , then she underwent oral xeloda for five cycles .
a laparotomy was performed and we found that the tumor arised from the pancreatic body and tail without breaking pancreatic capsule .
the distal pancreas , spleen , and its aneurysm were resected [ figures 2a and 2b ] .
( a ) the specimen removed from the pancreas , the tumor arised from the distal pancreas without breaking pancreatic capsule .
on pathologic examination , the size and the cut surface showed a milky - white solid and homogeneous tumor with a hard elastic consistency .
the tumor consisted of three types of cells , the majority being poorly differentiated adenocarcinoma cells with mucin products in their cytoplasm , and some moderately differentiated adenocarcinoma with a tendency to form ducts .
these epidermoid cells did not have definite intercellular bridges , keratohyaline , or keratin pearls .
no differentiated squamous carcinoma cells were detected in any part of the tumor [ figure 3 ] .
( h and e , 100 ) the tumor consisted of three types of cells , the majority being poorly differentiated adenocarcinoma cells with mucin products in their cytoplasm , and some moderately differentiated adenocarcinoma with a tendency to form ducts .
the cells of the tumor showed strong staining with antibodies to ck7 , ck5/6 , and cea , showed negative staining for ck20 , the proliferation index by ki-67 stain was above 30% .
the postoperative course was uneventful and the patient was discharged 2 weeks after the surgery .
gemcitabine was used once but the patient had severe gastrointestinal side - effects , then she underwent oral xeloda for five cycles .
the first documented case of mucoepidermoid carcinoma of pancreas was reported in 1959 by franz .
ohtsuki et al . suggested four hypotheses to account for the pathogenesis of the squamous component in pancreatic cancer , namely : ( 1 ) from pluripotent undifferentiated cells into mucin - producing cells and/or squamous cells ; ( 2 ) from ectopic squamous cells ; ( 3 ) from metaplastic squamous cells ; and ( 4 ) from the squamous metaplasia of underlying adenocarcinoma . in our report , the mucoepidermoid cells stained positively for ck7 , cea , and ck5/6 , but negatively for ck 20 . based on the ck immunoprofile , considering the present case ,
thus , a close follow - up is needed , to allow early treatment in case of recurrence .
ct or us ( ultrasound ) imaging is hard to distinguish mucoepidermoid carcinoma from the other types of pancreatic tumors before operation . for our case , though the mass can be identified on the body and tail of pancreas , we can not judge the specific from the preoperative imaging .
only seven cases of mucoepidermoid carcinoma of the pancreas have been reported , except that of our patient [ table 1 ] .
the ages of the patients ranged from 48 to 69 years , with the median age of 60.5 years , and five were male and three female .
the tumors were located at different sites of the pancreas ( two at the head , three at the body , two at the tail , and one at the body and tail ) and were all larger than 3.5 cm in diameter at the time of diagnosis .
all cases were advanced and every tumor grew invasively except our case , with six of the eight cases showing metastatic lesions in the liver and/or lymph nodes .
only one case was survival more than 11 months in previous cases and our patient merely survived for 12 months .
based on the experience of this case , surgery seems to be only modality which brings the hope of cure if the mass is resectable .
cases of mucoepidermoid carcinoma of the pancreas mucoepidermoid carcinoma is thought to be a subtype of adenosquamous carcinoma , histologically characterized by the presence of two components : an adenocarcinoma and a squamous carcinoma , but stewart et al .
mucoepidermoid carcinoma is composed of three types of cells , including mucin - producing cells , epidermoid cells , and cells intermediate between basal cells and epidermoid cells , mixed in various proportions . as far as mucoepidermoid carcinoma of pancreas
be concerned , ordinary tubular and/or papillary adenocarcinomatous structure would not be detected in the pancreatic lesion , and cancer cells can produce mucin .
ultrastructural examination shows that some of the cancer cells possess intracytoplasmic lumina surrounded by bundles of tonofilaments , squamous , and undifferentiated cells with transitional forms .
our case should be designated as mucoepidermoid carcinoma rather than adenosquamous carcinoma which are composed of mucin - producing cells , epidermoid cells , and cells intermediate between basal cells and epidermoid cells .
in summary , mucoepidermoid carcinoma of pancreas can not be differentiated from pancreatic adenocarcinoma by the preoperative examination , and surgery is still the only effective treatment if the mass was resectable .
due to limited cases of this disease reported , the effective diagnostic and therapeutic approach can not be figured out .
 mucoepidermoid carcinoma of the pancreas is rare . here , a 63-year - old woman with left upper abdominal pain and abdominal distension is presented . 
 her mucoepidermoid carcinoma was located at the left upper abdomen , arising from the pancreatic body and tail without invasion of pancreatic capsule . on pathologic examination , 
 the tumor consisted of three types of cells , the majority being poorly differentiated adenocarcinoma cells with mucin products in their cytoplasm , and some moderately differentiated adenocarcinoma with a tendency to form ducts . 
 in addition , there were epidermoid cells and intermediate undifferentiated cells . 
 she survived for 12 months after surgery . 
INTRODUCTION
CASE REPORT
Operative findings
Pathologic examination
Immunohistochemical findings
DISCUSSION
CONCLUSIONS