Solid pseudopapillary neoplasm of the pancreas in two male patients: gender does not matter

Solid pseudopapillary tumour (SPT) is an unusual pancreatic neoplasm which predominantly affects young women. Less than 10% of patients with SPT in the reported literature were male. In this paper, the authors report two new cases of SPT that occurred in two male patients aged respectively 25 and 20 years old. Abdominal computed tomography scan showed a well-defined heterogeneous mass involving respectively the tail and the body of the pancreas with peripheral calcifications in the first case. The two patients underwent distal splenopancreatectomy. Histopathological examination of the surgical specimen coupled with immunohistochemical study was compatible with solid pseudopapillary tumour. On postoperative day 8, the first patient developed abdominal wall abscess and peritoneal collection. Postoperative course was uneventful for the second patient. In summary, a large, well-encapsulated cystic mass in the pancreas of a young man should raise suspicion of solid pseudopapillary tumour.


Introduction
Solid pseudopapillary tumour (SPT) of the pancreas is an uncommon neoplasm accounting for 0,13-2,7% of all exocrine pancreatic tumours [1]. It is well known for its indolent behaviour and favourable prognosis with a predilection for young women. Less than 10% of patients with SPT in the reported literature were male [2]. With the widespread availability of high-quality imaging systems and a better understanding of its pathology, the number of cases of SPT reported in the literature has been steadily increasing [3]. In this paper, we report two new cases of SPT that occurred in male patients. Over the last seven-year period, four cases of SPT were diagnosed at the pathology department of Mongi Slim Hospital.
They included two female and two male patients with a sex-ratio (M/F) = 1. The aim of the present study was to highlight the clinicopathological features of this relatively rare neoplasm with review of the current literature.  Postoperative course was uneventful. At present, the patient is still being followed up.

Discussion
Solid pseudopapillary tumour of the pancreas was first described by  [3]. The age at diagnosis ranges from 2 to 85 years with a mean age of 21,9 years [2]. Compared with female patients, male patients were older, with an average age of 43,1 years. Our patients were aged 25 and 20 years old respectively. The initial presentation of SPT is usually nonspecific.
Upper abdominal pain is the most common symptom (46.5%), followed by a slowly enlarged, palpable, non-tender upper abdominal mass (34.8%). One of our patients presented with a fivemonth history of abdominal pain and slowly enlarged, palpable, non-tender upper abdominal mass and the second patient presented with epigastric pain. The most common location of the SPT is the tail (35.9%) and the head (34%) of the pancreas [2]. Accurate preoperative diagnosis of SPT is difficult because of the similarity of the findings among cystic lesions of the pancreas. On radiological examinations both a capsule and intratumoral haemorrhage are important clues to the diagnosis because they are rarely found in other pancreatic neoplasms [4]. On ultrasonography, CT scan or MRI, the lesion is usually large, its internal structure goes from cystic thick-walled or with an inner irregular margin to a predominantly solid mass with some cystic component [4]. Although some imaging characteristics are suggestive of SPT, percutaneous fine needle cytology of the cystic wall can be used to obtain a possible preoperative histological diagnosis [5]. Complete surgical removal with en bloc resection of the involved organ is the treatment of choice. Distal pancreatectomy with or without splenic preservation can be performed for tumours in the body or tail of the pancreas, and a classic or pylorus-preserving pancreaticoduodenectomy for tumours of the pancreatic head [6].
In contrast to conventional ductal adenocarcinomas, complete surgical resection of SPT has been reported to provide a more than 95% cure rate [6]. The majority of SPT are considered to be of low malignant potential with only 10-15% of cases being malignant, showing local infiltration, recurrence or distant metastasis [7,8].
There are few data available in the literature regarding the into the surrounding normal pancreatic tissue and vascular invasion [7]. Other studies indicate that DNA aneuploidy, double loss of X chromosomes, trisomy for chromosome 3, unbalanced translocation between chromosomes 13 and 17 found in SPT patients are associated with its aggressive behaviour and may be indicators of its possible metastatic potential [11,12]. The pathogenesis of SPT still remains unknown. Many investigators believe it to arise from a multipotential primordial stem cell. Some authors reported that 62,5% of SPT patients are infected with hepatitis B virus (HBV), which can induce over-expression of β-catenin in tumour cells, indicating that HBV infection may be involved in the pathogenesis of SPT, which, however, has not been confirmed [13].

Competing interests
The authors declare no competing interests.

Authors' contributions
Dr Faten LIMAIEM was the principle investigator who prepared,