Spontaneous regression in solid pseudopapillary neoplasm of pancreas.

A solid pseudopapillary neoplasm (SPN) of the pancreas is a rare neoplasm that mainly occurs in young women. We herein report the case of spontaneous regression in SPN of the pancreas. A 48-years-old female was found to have a mass in the head of the pancreas on examination for her back pain and referred to our hospital in 20XX. Laboratory data showed no abnormalities in serum levels of pancreatic enzymes and tumor markers. A contrast CT scan of upper abdomen showed a slightly enhanced lesion (23 × 19 mm in diameter) without cystic component or fibrous capsule in the head of the pancreas. An MRI scan showed the mass as low-intensity in T1-WI and high-intensity in T2-WI. She admitted to our hospital for further examination of a pancreatic mass by EUS-FNA in 20XX + 4. EUS showed a slightly hypoechoic mass (30 × 19 mm in diameter) compared with the neighboring normal pancreas. Tumor margin was relatively clear and the internal echo image was homogenous. Histological findings revealed a solid and pseudopapillary proliferation of eosinophilic polygonal cells with oval nuclei. The tumor cells were positive for vimentin and CD10 in the cytoplasm and β-catenin in the nuclei, which led to the diagnosis of SPN. We recommended this patient to undergo surgical resection, however, the patient chose follow-up examinations. Follow-up study after 1 year using MRI scan showed spontaneous regression, which was coincided with her menopause. These findings suggest that the natural regression of SPN may occur and female sex hormone changes may regulate the growth of SPN.