Solid pseudo papillary tumor of the pancreas: An unusual tumor in children.

An 11-year-old girl with a pancreatic solid pseudo papillary tumor (SPT) is reported. Contrast enhanced computerized tomography (CECT) & Magnetic resonant imaging (MRI) abdomen revealed a well-defined inhomogenous mass arising from the retro-peritoneum in the left upper quadrant of the abdomen possibly from the tail of the pancreas. USG guided biopsy of tumor showed benign pseudo papillary tumor of pancreas. Complete excision of the tumor was carried out. Histopathology revealed pancreatic pseudo papillary tumor. Patient did well postoperatively & is on regular follow-up.

INTRODUCTION

Solid pseudo papillarytumor (SPT) of the pancreas is a rare, benign to low-grade malignant epithelial tumor that occurs mainly in young females in second to fourth decades of life. Frantz first described this tumor in 1959, and in 1996, the World Health Organization (WHO) renamed this tumor as SPT.[1] Deep pancreatic parenchymal invasion and angioinvasion are features of malignant SPT, also called as solid pseudo papillary carcinoma.[2]

CASE REPORT

An 11-year-old female child, otherwise in good overall health, presented with pain and heaviness in the left side of abdomen for 5 months. She also had fatigue, nausea, and occasional vomiting which was not related to food. There was no weight loss, jaundice, diarrhea, or flushing. The examination revealed a large retroperitoneal lump extending from epigastrium to the left flank. An ultrasonography (USG) of the abdomen showed a 13×13 cm heterogeneous, hyperechoic retroperitoneal mass, displacing the major vessels. Contrast-enhanced Computerized tomography (CECT) scan revealed a well-defined heterogeneous mass arising from the retroperitoneum in the left upper quadrant of the abdomen possibly from the tail of the pancreas [Figure 1]. Magnetic resonance imaging (MRI) of the abdomen confirmed pancreatic tail neoplasm with solid and cystic lesions in T1-weighted imaging. Tumor markers like Alpha-fetoprotein (AFP), Beta-HCG, CA19-9 and Carcinoembryonic antigen (CEA) were within normal limits. An USG guided biopsy of the mass showed pseudo papillary tumor of the pancreas. Complete excision of this mass was done safeguarding splenic and renal vessels with closure of the pancreatic duct. The histopathology revealed the tumor to be an SPT of the pancreas [Figure 2]. The patient is on regular follow-up and well with no recurrence till 6 months of follow-up.

Figure 1

Contrast-enhanced computed tomogram(CECT) image (transverse cut) showing tumor in left hypochondrium displacing major vessels

Figure 2

Histopathology showing pseudo papillary pancreatic epithelium

DISCUSSION

SPT of the pancreas is a rare exocrine pancreatic tumor, which comprises only 1-2% of all tumors of the pancreas, first described by Frantz in 1959.[1] This uncommon, typically benign tumor seems to have a predilection for Asian and African-American women, although rare cases have been reported in children and men. Patients with SPT of the pancreas often are clinically asymptomatic or present with a gradually enlarging abdominal mass.[23] Its incidence in children is 8-16.6%.[45] The medical literature counts almost 500 cases, most of which have been identified in the last 25 years.[6] Mao[7] in a cumulative review of the literature found that 90% of patients were females with a mean age of 23.9 years. The male:female ratio is 1:9.5.[8] It has a low-grade malignant potential. It tends to be fairly benign in young females but appears to be more aggressive in older males, whose mean age is about 10 years older than women.

Review of the literature revealed 92 cases of SPTs of the pancreas reported in children[1-17] with an average age of 10.5 years (range 8-16 years) and a male:female ratio of 1:4. The number of cases contributing to head, body, body & tail, and tail were 38,11,9, and 18, respectively. Wang et al.[9] reported an SPT in three children (two girls 11 and 14 years of age and a boy 10 years of age) and concluded that the tumor arises early in life, grows slowly, and rarely metastasizes. In 2006, Choi et al.[10] performed retrospective review of 23 cases. Four patients (17%) had a history of abdominal trauma. Operative procedures performed were pylorus-preserving pancreaticoduodenectomy (n=6, 26.1%), distal pancreatectomy (n=7, 30.4%), distal pancreatectomy with splenectomy (n=7, 30.4%). Akker et al.[12] in 2012 performed retrospective review of 18 cases of SPT which showed females with SPT have an excellent outcome, even in presence of positive margins, suggesting that limited surgical resection may be appropriate for these patients.

The origin of this tumor remains an enigma. Kosmahl[13] favors an endocrine origin. The female predominance along with the presence of progesterone receptors in some reported cases suggests a neuroendocrine origin. CECT[14] and MRI features can be highly suggestive for the diagnosis of SPT. This tumor should be considered for a well-marginated, large, encapsulated, solid and cystic mass with areas of hemorrhagic degeneration, as revealed by high-signal intensity on T1-weighted imaging.[15]

Since the tumor is usually surrounded by a pseudocapsule and exhibits benign or low-grade malignancy, conservative resection with preservation of as much pancreatic tissue as possible is the treatment of choice.[17] Other therapies are indicated only in the few cases in which the tumor is unresectable. The biologic behavior of SPT is less aggressive than that of many other pancreatic tumors, and its prognosis is better. Surgical extirpation of the tumor will result in almost total survival (>95%) for those patients with tumors confined to the pancreas at presentation.

Malignant SPT designated as a solid pseudo papillary carcinoma occurs in 15% of adults and 13% of children with a significant increase in the elderly and male patients. According to the WHO classification system, the criteria for distinguishing the malignant form of the tumor “SPT carcinoma” comprises angioinvasion, perineural invasion, and deep invasion of the surrounding pancreatic parenchyma and metastasis. As for metastases, the most common site is the liver; lymph node and peritoneal spread are rarely reported.[217]