In this series we report the clinic-pathological and surgical outcome of rare pancreatic solid pseudopapillary neoplasm. All patients underwent regional pancreatectomy and only one out of 14 patient developed recurrence who later succumbed to disease progression. The management of remnant pancreatic stump, especially after pancreaticoduodenectomy was difficulty management due to its soft texture and undilated duct. In our series majority of patient had acceptable post-operative morbidity and there was no perioperative mortality.
Given its rarity and lack of unique identity, in the past it has also been misdiagnosed as adenocarcinoma, islet cell tumor, cystadenoma, papillary cystadenocarcinoma, or cystadenocarcinoma.8 Until its identity was standardized by WHO in 1996, it was described by a variety of names, like papillary epithelial neoplasm, solid and cystic acinar cell tumor, papillary cystic neoplasm, papillary cystic carcinoma, solid & cystic tumor, low-grade papillary tumor, and Frantz's tumor. WHO classified this tumor into low grade malignant neoplasm.14,15 Still there are no accurate criteria to define malignant behaviors in these tumors. Many studies used the arbitrary criteria to predict malignancy, that includes tumor size > 5cm, vessels invasion, incomplete capsule and pancreatic duct involvement but none of these are accurate predictors.16,17
SPN is a disease of young female and rare in males.5,18 The median age of the presentation is 28.5 years.10 In our series the presentation was at an young age ( 19.5 years) and all patients were female. The most common presenting symptom in our series was pain abdomen followed by lump. The most common reported symptoms in literature is pain abdomen or discomfort, which was reported in 63%to 81% of patients.5,10 Due to improved imaging techniques and awareness of the disease the incidental diagnosis of the SPN has been reported in 9–39.% of patients.5,6,8,19−21 The less commonly reported symptoms being palpable lump, nausea, vomiting and weight loss. Rarely these tumours may presents with Jaundice and pancreatitis.10
Routine laboratory parameters or tumor markers are of no help for the diagnosis of SPN.4 Although the imaging findings of SPN are not specific they are highly suggestive in appropriate clinical setting.21 CECT being the most common imaging modality used, the second most common modality is transabdominal USG, followed by MRI and EUS.10 Cross sectional images usually show a large well-circumscribed, heterogeneous mass with varying solid and cystic components, generally demarcated by a peripheral capsule and occasional calcification.4 A retrospective imaging-pathological correlation study concluded that a large well encapsulated mass that demonstrate calcification and regions of haemorrhagic degeneration in a young woman is virtually diagnostic of SPN.21 MRI is superior to CT in distinguishing certain tissue characteristics, such as haemorrhage, cystic degeneration or the presence of a capsule and may suggest correct diagnosis.21,22 There is no consensus on the utility of EUS/EUS-FNAC in the diagnosis of SPN. The reported diagnostic accuracy of EUS FNAC is from 56–81%. 23,24 A recent multicentric study reported the safety of EUS-FNAC and showed no impact of this procedure on long term recurrence of the disease.24 Though not necessary in every case, EUS FNAC procedure can be utilised in diagnostic dilemma especially in pancreatic head lesions. In the current study EUS was done in six patients and EUS-FNAC in four patients, three out of these four was confirmatory for SPN.
SPN is solitary tumor of pancreas, though multicentric and extra-pancreatic tumors have been reported in literature.25,26 Most common location in pancreas is the body and tail (59.3%) followed by the head or uncinate process (36%) and 1.1% were extra-pancreatic tumors.10 But in our study the most common location of tumor was head/uncinate of pancreas (57%). Most SPN are large, sometime partially encapsulated mass with a mixture of solid and cystic component (foci of haemorrhage) in various proportions.6,8 However the gross appearance depends to some extent on the size of the tumor. While the smaller tumors tend to be homogenously solid, soft, less sharply circumscribed, tan to red mass with variable amounts of fibrosis; larger tumors commonly have a fibrous pseudo capsule surrounding the tumor usually demarcating it from the surrounding pancreatic parenchyma.9 Two out of 14 patients in our series had solid homogenous mass and these tumor were relatively small in size (largest diameter − 2.8 cm and 5.3 cm).
Complete surgical excision is the standard of care for SPN. Surgery depends on the location of tumors, for pancreatic head lesion ,pancreaticoduodenectomy and for pancreatic body and tail lesion central or distal pancreatectomy with or without splenectomy is surgery of choice. The enucleation or parenchymal sparing resection for these tumors has been reported .But this treatment strategy is associated with increased risk of resection margin positivity and post-operative recurrences.27 The reported incidence of lymph node metastasis is low (0.5%- 2.2%), so routine lymphadenectomy is not recommended.10,28 With surgical resection SPN has very good prognosis, even for tumor with metastases or invasions.9,10 Local invasion, recurrence, or limited metastases are not contraindications for resection.9 In a recent systematic review and meta-analysis of predictors of recurrence, male gender, positive lymph node, R1 resection and LVI were associated with a statistically significant odds for recurrence.11However many studies did no shows any significant relation of disease recurrence with male gender ,tumor size, R1 resection, local invasion ,and lymph node positivity.23,24,27 The Prognostic criteria’s for disease behaviour is not well characterised in the literature. In our study one patient each with R1 resection and portal vein invasion had no disease recurrence and are alive .One patient who had no local invasion with R0 resection had disease recurrence 48 months after surgery.
In conclusion, solid pseudopapillary neoplasm of pancreas is a rare tumour with malignant potential. There is no definitive preoperative predictors for malignancy. Hence oncological resection should be performed for potential cure.