Solid Pseudopapillary Neoplasm of the Pancreas
Waithaka M1 , Mutuiri A2, Gakinya S2
Pathologists Lancet Kenya
Aga Khan University Hospital, Nairobi, Kenya
Correspondence to: Dr. Wairimu Waithaka. P. O Box 14563 Nairobi 00800 Kenya. Email: wairimu.waithaka@ yahoo.com
Solid pseudopapillary neoplasm is a rare pancreatic tumour predominantly affecting young women. We present two cases in young female patients. Both tumours were surgically removed as abdominal masses, one from the pancreatic tail and the other posterior to the stomach with an unclear organ of origin. On gross examination, both tumours were encapsulated with solid and cystic cut surfaces that had hemorrhage and necrosis. On histological examination, both were composed of solid sheets and pseudopapillae lined by bland, monotonous and uniform round cells. One tumour had features of malignancy. Immunohistochemistry for both cases was consistent with solid pseudopapillary neoplasm. Solid pseudopapillary neoplasm should be considered in the differential in young women presenting with pancreatic masses.
Key Words: Pseudopapillary, Neoplasm, Pancreas
Solid pseudopapillary neoplasm (SPN) of the pancreas is rare, accounting for 2-3 % of primary pancreatic tumours (1). It was first described by Frantz in 1959 and has since then been referred to as: solid and cystic tumour, solid and papillary neoplasm, Frantz’s tumour, papillary-cystic neoplasm and papillary epithelial neoplasm. It was finally defined by the World Health Organization (WHO) in 2000 as a solid pseudopapillary neoplasm of the pancreas (2). SPN is considered a low malignant potential neoplasm, due to its benign morphology and the fact that it rarely metastasizes (3). Even though pancreatic tumours generally have bad prognosis, SPN shows good prognosis, which makes the disease entity unique in this disease group. To predict malignant behavior of SPN, several morphological criteria are needed (angioinvasion, invasion to surrounding tissue or unequivocal perineural invasion) and if present, the tumour should be designated as solid pseudopapillary carcinoma (SPC) (4). We present two cases of SPN, highlighting histologic and immunohistochemical features.
Distal pancreatectomy specimen was received from a 24 year-old female with an encapsulated tumour at the tail of the pancreas. On gross examination revealed encapsulated, ovoid tumour measuring 13 x 8 x 7.5 cm. There was attached normal pancreas measuring 4 x 2 x 2 cm. The cut surface had both solid and cystic areas with necrosis and haemorrhage (Figure 1a). Histology showed a tumour with both solid and pseudopapillary foci composed of uniform cells with bland round nuclei and moderate eosinophilic cytoplasm. The pseudopapillae had hyalinised cores with mucinous change. Clusters of cholesterol clefts were also seen. Vascular invasion was identified (Figure 1b-f). The surgical resection margins were positive for tumour. Immunohistochemistry results were as follows: vimentin – positive, CD10 – positive, CD99 – paranuclear dot-like positivity, progesterone receptor – positive (Figure 1 g-i).
The tumour was diagnosed as a solid pseudopapillary carcinoma
The second case was a biopsy received from a 15 year-old female patient and was described as a huge mass behind the stomach, the site of origin was queried at surgery as either posterior gastric wall or retroperitoneal origin. The liver and spleen were described as normal. A gastrointestinal stromal tumour was suspected clinically. Gross examination, a grey encapsulated nodule measuring 3x2.5x2 cm was received. It weighed 80 grams. The cut surface was solid and white with a black, cystic focus. Histology showed an encapsulated tumour composed of solid sheets and pseudopapillae lined by bland cells with moderate cytoplasm and regular nuclei with even chromatin distribution. Focal areas of mucinous change were present (Figure 2 a, b). The surgical resection margins were positive. Immunohistochemistry results were as follows: cytokeratin AE1/AE3 – positive, vimentin – positive, CD10 – positive (Figure 2 c, d).
The tumour was diagnosed as a solid pseudopapillary tumour of pancreatic origin.
Gross appearance. Note the capsule as well as cystic, necrotic and haemorrhagic cut surface. Solid growth of monotonous round cells and perineural invasion. (Haematoxylin & Eosin stain, X4). c) Pseudopapillae lined my monotonous, uniform round cells. There is mucinous change of the cores. (Haematoxylin & Eosin stain, X10). d) Lymphovascular invasion (Haematoxylin & Eosin stain, X10). e) Cholesterol clefts. (Haematoxylin & Eosin stain, X10). f) Necrosis. (Haematoxylin & Eosin stain, X20). g) Vimentin immunostain, diffuse and intense staining. (X20). h) Progesterone receptor immunostain, strong