Synchronous solid pseudopapillary neoplasm and invasive ductal carcinoma of the pancreas: a case report

BACKGROUND: Solid pseudopapillary neoplasm (SPN) of the pancreas is an extremely rare neoplasm with a favorable prognosis. On the other hand, pancreatic invasive ductal carcinoma (IDC) is known to be an aggressive malignancy. To the best of our knowledge, there is no report of SPN combined with IDC of the pancreas. CASE PRESENTATION: A 66-year-old woman presented with abnormal genital bleeding and was diagnosed with inoperable cervical cancer. During computed tomography for cancer staging, the patient was incidentally diagnosed with pancreatic cancer. After radiation therapy for the cervical cancer, distal pancreatectomy with D2 lymph node dissection was performed. A postoperative pathological examination revealed SPN with ossification and well-differentiated IDC in the pancreatic body. On immunohistochemical staining, SPN tumor cells showed positive β-catenin and CD10 staining, whereas IDC cells were negative for both. The tumor boundaries were clear. Accordingly, the final pathological diagnosis was synchronous SPN and IDC of the pancreas. Moreover, pathological findings such as the ossification and small number of SPN cells suggested that SPN may have existed long before IDC initiation. CONCLUSIONS: Here, we report the first case of SPN combined with IDC of the pancreas. They may occur independently, and the long-term presence of SPN may lead to the development of IDC.