Potential Role for Observation in Small Solid Pseudopapillary Neoplasm (SPN)

Background: Solid pseudopapillary neoplasms (SPN) are rare tumors of the pancreas, typically affecting young women. Resection is the mainstay of treatment but is associated with significant morbidity and potential mortality. We explore the idea that small, localized SPN could be safely observed. Methods: This retrospective review of the Pancreas National Cancer Database from 2004 to 2018 identified SPN via histology code 8452. Results: A total of 994 SPNs were identified. Mean age was 36.8 ± 0.5 years, 84.9% (n = 844) were female, and most had a Charlson–Deyo Comorbidity Coefficient (CDCC) of 0–1 (96.6%, n = 960). Patients were most often staged clinically as cT₂ (69.5%, n = 457) followed by cT₃ (17.6%, n = 116), cT₁ (11.2%, n = 74), and cT₄ (1.7%, n = 11). Clinical lymph node and distant metastasis rates were 3.0 and 4.0%, respectively. Surgical resection was performed in 96.6% of patients (n = 960), most commonly partial pancreatectomy (44.3%) followed by pancreatoduodenectomy (31.3%) and total pancreatectomy (8.1%). In patients clinically staged as node (N₀) and distant metastasis (M₀) negative, occult pathologic lymph node involvement was found in 0% (n = 28) of patients with stage cT₁ and 0.5% (n = 185) of patients with cT₂ disease. The risk of occult nodal metastasis significantly increased to 8.9% (n = 61) for patients with cT₃ disease. The risk further increased to 50% (n = 2) in patients with cT₄ disease. Conclusions: Herein, the specificity of excluding nodal involvement clinically is 99.5% in tumors ≤ 4 cm and 100% in tumors ≤ 2 cm. Therefore, there may be a role for close observation in patients with cT₁N₀ lesions to mitigate morbidity from major pancreatic resection.