Case Report: Delayed diagnosis of pancreatic solid pseudopapillary neoplasm in a boy initially misdiagnosed as traumatic retroperitoneal hematoma.

Solid pseudopapillary neoplasm (SPN) of the pancreas is a rare pancreatic tumor with low-grade malignant potential. It predominantly occurs in adolescent girls and young women but can also affect boys. SPN may contain hemorrhagic or cystic components that can be mistaken for a post-traumatic hematoma when patients present after abdominal injury. We report a 12-year-old boy whose pancreatic tail lesion was initially interpreted as a traumatic retroperitoneal hematoma after minor blunt trauma at age 7. Ultrasound-guided drainage yielded hemorrhagic fluid with non-elevated amylase levels and negative bacterial culture; however, cytological examination was not documented. The lesion persisted, and scheduled follow-up was subsequently discontinued. Approximately 4.5 years later, repeat evaluation demonstrated interval enlargement from approximately 5.6 cm to 10 cm. Imaging showed a complete thin capsule, mixed solid-cystic architecture, coarse calcification, and progressive enhancement, features that were not compatible with a resolving hematoma. After multidisciplinary reassessment, SPN was considered the most likely diagnosis. Laparoscopic spleen-preserving distal pancreatectomy was successfully performed, with an estimated blood loss of 30 mL. Histopathological examination confirmed SPN, with a Ki-67 index of approximately 2%, a negative stapled margin, and no tumor involvement in the sampled adjacent pancreatic or fibrofatty tissue. The patient did not develop a clinically relevant postoperative pancreatic fistula. During approximately 11 months of postoperative surveillance, no recurrence was detected. This case emphasizes that a presumed post-traumatic hematoma should be reassessed when it persists or enlarges. It also supports the feasibility of minimally invasive spleen-preserving resection in carefully selected pediatric patients.