Aggressive solid pseudopapillary neoplasm in a young male

An 18-year-old male presented to our institution with a several-week history of progressively worsening abdominal pain. Aside from the pain, the patient reported no other symptoms. Routine laboratory tests were within normal limits, and his past medical history was non-contributory.

An ultrasound was performed, revealing a heterogeneous mass with solid and hypoechoic characteristics, measuring 80 x 70 x 52 mm, located in the pancreatic tail. The mass had a multilobulated yet relatively well-defined contour.

A subsequent computed tomography (CT) scan showed a large lesion, likely neoplastic, originating from the tail/body region of the pancreas (Figures 1 and 2). The lesion measured 9 x 10 cm in its largest axial dimensions and extended over 17 cm. The mass completely encased the splenic artery and caused occlusion of the splenic vein (Figure 3). It exerted a mass effect on the stomach and left kidney (Figures 1 and 4). No clear plane of separation was observed between the lesion and the external limb of the left adrenal gland, the ligament of Treitz, or adjacent sections of the intestine. The liver parenchyma showed multiple nodular lesions with peripheral enhancement, suggestive of metastatic involvement (Figure 5). Additionally, free peritoneal fluid was detected, along with several areas of enhancement in the vesicorectal peritoneal recess (Figure 6).

Background

Solid pseudopapillary neoplasm (SPN) is a rare exocrine tumour of the pancreas. It is characterised by loosely cohesive epithelial cells that form both solid and pseudopapillary structures, and it frequently expresses progesterone receptors. These tumours are most often located in the body or tail of the pancreas and can grow considerably before causing noticeable symptoms. SPNs primarily affect females, with a female-to-male ratio of 9.8:1, and the average age of diagnosis is around 28.5 years [1]. While the exact cause is still unknown, many cases show somatic mutations in the β-catenin gene. Some studies suggest that the tumour may originate from centroacinar cells in the pancreas, and no known risk factors have been identified [1,2].

Clinical Perspective

This condition is often asymptomatic and typically discovered incidentally during imaging studies. It generally exhibits slow growth, with a low chance of local recurrence or metastasis, and has a high success rate with complete surgical removal. When symptoms do occur, abdominal pain is the most frequent. Though most pancreatic SPNs are benign, a small fraction can show more aggressive characteristics. These tumours may invade nearby tissues, demonstrating local aggression, or become malignant, spreading to the liver, peritoneum, or even distant organs like the lungs [3,4]. Some studies indicate that SPNs may behave more aggressively in men, where they tend to be larger and diagnosed at an older age compared to women [5]. Surgical excision is the definitive treatment, with excellent prognosis in typical cases. For unresectable lesions, some chemotherapy regimens and the use of radiotherapy have been indicated, although no definitive conclusions have been reached [6].

Imaging Perspective

Computed tomography (CT) is typically the imaging method of choice for these tumours. They usually appear as large, well-encapsulated masses with varying degrees of solid and cystic areas. The solid regions, often located at the outer edges, tend to be hypoattenuating in both unenhanced and contrast-enhanced portal venous phases. Calcifications can be present, and in men, these tumours often show a greater proportion of solid components. Pancreatoblastoma may present with similar imaging features; however, it typically occurs in children under the age of five and is associated with elevated alpha-fetoprotein levels. A neuroendocrine neoplasm is another differential diagnosis, though these tumours tend to be smaller and exhibit pronounced arterial enhancement.

Outcome

Following an interdisciplinary consultation involving surgical, oncological, and radiological specialities, the decision was made to proceed with a total gastrectomy, distal pancreatectomy (body and tail), segmental enterectomy, left hemicolectomy, and splenectomy.

Histological analysis of the surgical specimen confirmed the presence of a solid pseudopapillary neoplasm, with metastatic involvement in the liver and mesocolon.

Unfortunately, the patient passed away a few days later due to complications related to the surgery.

Take Home Message

Although it is a rare neoplasm, even rarer in young men, the diagnosis of solid pseudopapillary neoplasm (SPN) should be considered, particularly when a pancreatic tail mass with aggressive characteristics is present.

Written informed patient consent (from the mother of the patient) for publication has been obtained.