SPN of the pancreas is a rare neoplasm, accounting for approximately 0.3 to 2.7% of all pancreatic tumors . Most SPNs are diagnosed in young female patients under the age of 40 and reveal large tumors (mean tumor diameter 5.9 cm) . These tumors are frequently located in the distal pancreas and are latent malignancies with excellent prognosis [2, 4]. Most patients are cured after radical surgery, with an increasing number of minimally invasive surgeries for SPN . However, 10–15% of SPN cases have aggressive features, including lymphovascular invasion, adjacent organ invasion, and metastatic disease [6, 7]. Typical immunohistochemistry findings for SPN include positive staining for nuclear β-catenin and CD-10 [2, 8]. Characteristic imaging features of SPNs include a calcified peripheral rim. A previous study demonstrated calcification in 30.5% of SPN cases and ossification in only 3.3% . The present case was a SPN with both calcification and ossification, who was older than the mean age of diagnosis. On the other hand, the prognosis of pancreatic IDC is extremely poor . To the best of our knowledge, there is no literature of SPN combined with IDC of the pancreas, and the correlation with SPN and IDC remains to be clarified.
In the case presented here, SPN with no malignant features was adjacent to IDC. However, SPN was characterized by different grades of histologic atypia, with clear boundaries between them. Additionally, SPN was positive for β-catenin and CD10, but IDC was negative for these immunohistochemical stainings. As described above, we did not observe signs of histological transformation indicating a transition between SPN and IDC, and immunohistological features were different. These findings indicate that SPN and IDC may occur independently.
It is difficult to clarify what lesions preceded in this case using the preoperative assessment and the pathological findings. In the present case, the number of viable SPN cells was small, and the number of vitrified tissues was high. Additionally, ossification was also observed in the vitrified tissues. These findings suggest that SPN may have existed long before the development of IDC. Furthermore, the presence of SPN for a long period of time might have caused inflammation in the pancreatic tissue. Possible explanations for pancreatitis induced by SPN include two hypotheses. First, recurrent inflammation caused by SPN itself may affect surrounding pancreatic tissues. Iijima et al.  reported that calcification may be caused by recurrent inflammation and necrosis over a long period of time. In the present case, there was calcification without cystic components even inside the SPN. Furthermore, the patient was more than 20 years older than the mean age of diagnosis, which may suggest a more long-term presence of SPN. These findings suggest recurrent inflammation associated with SPN over a long period of time. Second, SPN with calcification and ossification could lead to MPD stenosis, resulting in inflammation of pancreatic tissues distal to SPN. Tajima et al.  reported a case of MPD stenosis caused by SPN with ossification. The present case presented SPN with calcification and ossification. Additionally, there was fibrosis with tissue destruction and exocrine parenchyma loss in pancreatic tissues distal to SPN, suggesting chronic pancreatitis. Based on these findings, SPN with calcification and ossification could lead to MPD stenosis, which might cause pancreatitis.
SPN cells show β-catenin staining in both the cytoplasm and nucleus due to the presence of a mutation in the gene that activates β-catenin expression. Aberrant cell cycle signaling through the β-catenin pathway has been associated with tumorigenesis in SPN and other cancers [12, 13]. Additionally, β-catenin signaling dysregulation is involved in chronic inflammation . As discussed so far, pathological findings of the present case may support the correlation with long-term presence of SPN and chronic pancreatitis. Furthermore, chronic inflammation leads to the collapse of homeostatic interactions in the tissue microenvironment , and chronic pancreatitis is considered to be a high-risk factor for pancreatic cancer [15, 16]. Based on these findings, the long-term presence of SPN may contribute to the development of IDC, even though SPN is a low-grade malignant tumor. Further studies are needed to clarify the relationship between SPN and IDC.
In the present case, a prognostic factor was not cervical cancer but pancreatic cancer. However, the patient had not yet been diagnosed with pancreatic cancer at the time the patient was diagnosed with inoperable cervical cancer. Moreover, few studies had reported the efficiency of neoadjuvant chemotherapy for resectable pancreatic cancer at that time. For this reason, the pancreatic tumor was inspected while performing radiation therapy for cervical cancer, and subsequently, distal pancreatectomy was performed without neoadjuvant chemotherapy. The present case was diagnosed with resectable pancreatic cancer, which is currently a candidate for neoadjuvant chemotherapy . Therefore, neoadjuvant chemotherapy and several watchful-wait interval for pancreatic cancer should be considered when the patient was diagnosed with pancreatic cancer and cervical cancer at the same time.
Postoperatively, the present case was diagnosed with multiple bone metastases, and she died 2 months after surgery. An autopsy was not performed because her family did not hope it, and the origin of bone metastasis remained unknown. Bone metastasis has been reported to occur in 5 to 20% of patients with pancreatic cancer, while in 1 to 16% of patients with cervical cancer [18,19,20]. Preoperatively, CEA, CA19-9, DUPAN-2, and Span-1 were elevated. However, tumor markers except for CEA and CA19-9 were not measured postoperatively. Furthermore, CEA and CA19-9 may be also elevated in cervical cancer. For this reason, it is difficult to predict a primary cancer from changes in tumor markers. Median survival of pancreatic cancer with bone metastasis was 7 months, while those of cervical cancer with bone metastasis was 34 months [21, 22]. Considering her course, the origin of metastasis may be pancreatic cancer rather than cervical cancer.