A solid pseudopapillary neoplasm without cysts that occurred in a patient diagnosed by endoscopic ultrasound-guided fine-needle aspiration: a case report

Abstract

Introduction: Solid pseudopapillary neoplasm of the pancreas is a rare neoplasm that has been reported to account for between 0.17% and 2.7% of all non-endocrine tumors of the pancreas. It is usually seen in young women. Because solid pseudopapillary neoplasms are rarely aggressive and have low-grade malignant potential and an excellent prognosis after complete resection, it is an ideal pancreatic tumor for treatment by minimally invasive surgery. Therefore, making an accurate pre-operative diagnosis is very important.

Case presentation: A 24-year-old Japanese man who had been found to have mild transaminase elevations at a medical check-up visited our hospital for further examination. Abdominal computed tomography showed a 40mm-diameter tumor in the pancreatic tail and mild fatty liver. He was admitted to our hospital for additional examination. The abdominal contrast-enhanced computed tomography scan taken at our institution showed an increasingly enhanced mass of 40mm diameter in the pancreatic tail. Ultrasonography showed a low-level echoic mass of 35mm diameter in the pancreatic tail. T1-weighted magnetic resonance imaging showed low signal intensity in the tail of the pancreas. T2-weighted magnetic resonance imaging showed high signal intensity there. Diffusion magnetic resonance imaging showed high signal intensity. An endoscopic ultrasound yielded the same results as the abdominal ultrasonogram. In addition, [18F]-fluorodeoxyglucose positron emission tomography/computed tomography showed abnormal accumulation (maximum standardized uptake value, 6.53). This finding raised our suspicion of a pancreatic malignant tumor. However, the patient could not be confidently diagnosed solely on the basis of imaging. Endoscopic ultrasound-guided fine-needle aspiration was performed, which led us to a diagnosis of solid pseudopapillary neoplasm. On that basis, we performed minimally invasive surgery (spleen-preserving laparoscopic distal pancreatectomy).

Conclusion: Atypical solid pseudopapillary neoplasm without cysts should be considered when diagnosing pancreatic tumors. A definitive pre-operative diagnosis of solid pseudopapillary neoplasm made on the basis of endoscopic ultrasound-guided fine-needle aspiration can guide the surgical approach used.

Figure 1

Abdominal computed tomography showing the solid pseudopapillary neoplasm in our patient. (A) This is a plain image, and it shows a mass of 40mm diameter in the pancreatic tail. (B) This is a contrast-enhanced image, and it shows an increasingly enhanced mass of 40mm diameter in the pancreatic tail.

Figure 2

Endoscopic ultrasound. These two images show a low echoic mass of 35mm diameter in the pancreatic tail. (The left image shows a whole image and the right image shows an enlarged image. The dotted lines show lines of measurement for this tumor.)

Figure 3

¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography scans of the solid pseudopapillary neoplasm in our patient. This fused image shows abnormal accumulation in the mass (maximum standardized uptake value, 6.53).

Figure 4

Histopathological images of samples taken during endoscopic ultrasound-guided fine-needle aspiration. (A) The tumor cells with round nuclei show pseudopapillary growth (hematoxylin and eosin stain; original magnification, ×4). Immunohistochemically, the tumor cells stained positive for CD10 (original magnification, ×10) (B), progesterone receptor (original magnification, ×10) (C) and vimentin (original magnification, ×10) (D).

Figure 5

Peri-operative photograph showing the pancreas. Our patient was treated with a spleen-preserving laparoscopic distal pancreatectomy. The pancreas (arrow) was transected using a 60mm endoscopic gastrointestinal anastomosis stapler.

Figure 6

Macroscopic images of the specimen. Our examination of the resected specimen revealed a solid tumor extending to the tail of the pancreas. The tumor did not contain calcified or cystic areas.