Epidermoid cyst of intrapancreatic accessory spleen is exceedingly rare; only 30 new cases have been reported in the English literature over the last 30 years.An accurate preoperative diagnosis was made in almost none of them because of the lack of reliable preoperative diagnostic methods. In this report, we present a case diagnosed with fluorine-18 fluorodeoxyglucose positron emission tomography(FDG-PET). A 41-year-old female who had breast cancer was routinely followed up by measuring the concentration of tumor makers.An increasing level of serum carbohydrate antigen 19-9was detected and a cystic lesion located at the tail of pancreas was found by ultrasonography. A whole body fluorine-18 FDG positron emission tomography was performed because of a high suspicion for either a malignancy of the pancreas or a recurrence of breast cancer.No increased uptake of FDG was noted and therefore the cystic lesion was considered as pancreatic benign disease. Because pancreatic malignancy could not be entirely ruled out, distal pancreatectomy and splenectomy were performed. The final pathological diagnosiswas epidermoid cyst of intrapancreatic accessory spleen(ECIAS). The FDG-PET findings matched the histopathology. A literature review reveals that the common clinical manifestations of ECIAS include asymptomatic findings on clinical examination, an occasional increase in tumor makers on laboratory results and occurrence only in the pancreatic tail. It is often misdiagnosed due to its extreme rarity and lack of a specific radiographic sign. There is no evidence of malignancy in ECIAS. Open or laparoscopic spleen preserving distal pancreatectomy is the minimally invasive procedure that would provide the best surgical management for epidermoid cyst of intrapancreatic accessory spleen. Epidermoid cyst of intrapancreatic accessory spleen is exceedingly rare; only 30 new cases have been reported in the English literature over the last 30 years. An accurate preoperative diagnosis was made in almost none of them because of the lack of reliable preoperative diagnostic methods. report, we present a case was diagnosed with fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET). A 41-year-old female who had breast cancer was routinely followed up by measuring the concentration of tumor makers. An increasing level of serum carbohydrate antigen 19-9was detected and a cystic lesion located at the tail of pancreas was found by ultrasonography. A whole body fluorine-18 FDG positron emission tomography was performed because of a high suspicion for either a malignancy of the pancreas or a recurrence of breast cancer .No increased uptake of FDG was noted and therefore the cystic lesion was considered as pancreatic benign disease. Because pancreatic malignancy could no The final pathological diagnosis was epidermoid cyst of intrapancreatic accessory spleen (ECIAS). The literature review reveals that the common clinical manifestations of ECIAS include asymptomatic findings. on clinical examination, an occasional increase in tumor makers on laboratory results and occurrence only in the pancreatic tail. It is often misdiagnosed due to its extreme rarity and lack of a specific radiographic sign. There is no evidence of malignancy in ECIAS. Open or laparoscopic spleen preserving distal pancreatectomy is the minimally invasive procedure that would provide the best surgical management for epidermoid cyst of intrapancreatic accessory spleen.