The majority of the tumours of the exocrine pancreas include adenocarcinoma, intraductal papillary mucinous neoplasm, mucinous cystadenocarcinoma and acinar cell carcinoma.[1] They are aggressive tumors with a poor survival rate.

Solid pseudopapillary neoplasm develops from the exocrine pancreas and has low malignant potential. First described by Virginia Frantz in 1959, it constitutes 0.2 to 2.7 % of all the neoplasms of the exocrine pancreas [2] and 5% of the cystic neoplasms. [3]

The diagnosis is suspected on imaging features demonstrating large encapsulated tumour with solid and cystic spaces. Solid pseudopapillary neoplasm occurs almost exclusively in young women and usually follow a benign course and are curable with excision.

SPNP pose a diagnostic challenge both clinically and radiologically due to their vague clinical presentation and varying degree of cystic degeneration, haemorrhage, and necrosis mimicking pseudocyst and even malignancy. [4] We present a case of a 32-year-old lady diagnosed with solid pseudopapillary neoplasm with emphasis on its clinicopathological features and histo- radiological findings.

A 32 years old post-cholecystectomy female presented in our hospital with a history of vomiting and fever for 15 days. There was yellowish discolouration of the eyes for 15 days and pain in the right upper quadrant of the abdomen. On examination, there was the presence of icterus. Per-abdomen was soft, non-distended, non-tender with no organomegaly.

On MRCP, abrupt tapering of distal CBD with suspicious filling defect with dilated IHBR was seen. (Figure 1A). However, no growth was detected. ERCP showed distal CBD stricture and oedema in the papillary region. CA 19.9 levels were normal. LFT showed bilirubin 2.5 mg/dl and ALP level was 375 IU/L. Abdominal CECT revealed a well-defined round soft tissue density measuring 2.4 x 1.8cm in the ampullary/Periampullary region abutting head and CBD with dilated IHBR. (Figure 1B)

Figure 2A- Per-operative photograph of Whipple specimen showing a resected pancreatic head with the tumor along with the part of duodenum.

Figure 2B- Gross photograph showing encapsulated well-circumscribed tumor in the head of the pancreas with surrounding normal pancreatic tissue.

Figure 3A- Low power microphotograph showing well defined capsule with underlying solid nests of poorly cohesive cells forming a cuff surrounding blood vessels, resulting in a pseudopapillary architecture. (H & E, 10x).

Figure 3D: Immunohistochemistry showing positivity for chromogranin in tumor cells. (IHC, 40x).

Whipple’s procedure was done and intraoperative findings showed a large approximately 3x3cm mass in the periampullary region in the head of the pancreas with grossly dilated CBD with multiple periportal and peripancreatic lymph nodes. (Figure 2A) Pancreaticoduodenectomy specimen, peri-choledochal tissue and periportal lymph nodes were received in the histopathology lab for evaluation. (Figure 2B) On histopathological examination, a well-demarcated, encapsulated tumor composed of uniform monotonous round to oval cells in solid sheets, cords and organoid pattern with the presence of pseudopapillae were seen. (Figure 3A). Cells exhibited mild pleomorphism with finely dispersed chromatin, eosinophilic cytoplasm and inconspicuous nucleoli. Few cells showed longitudinal grooving. (Figure 3B) Some of the tumor cells showed PAS-positive hyaline globules in their cytoplasm. (Figure 3B inset) No atypical mitosis was seen. All margins and all lymph nodes were free of tumor. Histopathological diagnosis of Solid pseudopapillary neoplasm of the pancreas was given and immunohistochemistry was advised to confirm the diagnosis and rule out histopathological mimics which include pancreatic endocrine neoplasm and acinic cell carcinoma. Immunohistochemical stains showed nuclear positivity for β-catenin (Figure 3C), and chromogranin (Figure 3D) and were negative for CD-10.

The solid pseudopapillary neoplasm of the pancreas is a rare neoplasm of the exocrine pancreas almost exclusively found in females. The mean age for SPTP is 25-35 years and is very uncommon in males, children, and older females. [5]

SPTP is characterized by a long asymptomatic course and patients usually present with vague gastrointestinal symptoms. Therefore, it is not unusual that they are missed on initial evaluation and detected only when grown to a remarkable size.[6] This was seen in our case also when six months back initial radiological evaluation is done in our patient for gallbladder disease did not reveal any pancreatic abnormality. The clinical findings and the radiological features of SPNP can help in making the correct diagnosis and in differentiating these lesions from other pancreatic neoplasms.

Acinar cell carcinoma (ACC) differs from SPTP by its prominent acinar formation, cells with finely granular cytoplasm and positivity for pancreatic enzymes with variable staining for β-catenin. In our case tumor cells were negative for CD10 and trypsin. Pancreatoblastoma shows primitive pancreatic elements with acinar, ductal and neuroendocrine differentiation; also squamoid corpuscles; more common in children younger than 10 years; positive for β-catenin (80%), neuroendocrine markers and pancreatic enzymes(trypsin, chymotrypsin and lipase). Diffuse immunostaining for β-catenin has been found in the cytoplasm and nuclei of SPNP, in contrast to the predominantly membranous reactivity in PNN and ACC (25% may show nuclear staining), which may be helpful in distinguishing between SPTP and such neoplasms. [10]

Through this case report, we wish to emphasize that a high index of suspicion is necessary to diagnose Solid pseudopapillary neoplasm as it carries a good prognosis and its diagnosis should always be considered in a young female presenting with a pancreatic mass. Moreover, the histopathologist needs to be aware of its histopathological mimics with judicious use of a select panel of immunostains for its definitive diagnosis.