True congenital epithelium-lined cysts of the pancreas are rare, and the prenatal diagnosis of a true pancreatic cyst has been reported only rarely (Kazez et al., 2006 & Song et al., 2007). It is a very rare cause of a cystic lesion of the pancreas comprising less than 1% of all pancreatic cysts. Most of these are reported in children less than 2 years of age (Agarwala et al., 1999).
Kazez et al., (2006) had reported a case of congenital true pancreatic cyst with a high level of enzymatic activity of a 4-month-old boy was admitted to the clinic with a history of abdominal swelling for one month. A mobile, smooth, non-tender mass was palpated on the left side of the abdomen during physical examination. Ultrasonography and MRI imaging revealed a bilocular cystic mass sized 9.5 x 8 x 6 cm. The spleen was displaced superiorly, whereas the left kidney was displaced posteriorly.
Obliteration of the peripancreatic fat planes between the cystic mass and tail of the pancreas was observed. During abdominal surgical exploration, the pancreatic tail was larger than normal, and a pancreatic cyst arising from the tail of the pancreas was observed. Total cystectomy was performed with distal pancreatectomy.
Song et al., (2007) had reported a case of a 3-day-old girl with histologically proven true pancreatic cyst that was detected by prenatal ultrasonography. The cystic mass was located in the left upper side of the abdomen, and total cystectomy was performed without complication.
Dipaola et al., (2002) had reported a case of congenital true pancreatic cyst in otherwise asymptomatic boy aged 4 years, whereas Agarwala et al., (1999) described a case of congenital true pancreatic cyst in a 6 years old girl with the clinical, radiological and pathological details and the surgical treatment.
Solitary true cyst of the pancreas is rare in adults (Fiamingo et al., 2005), and the differential diagnosis of cystic lesions of the pancreas is challenging (Takahashi et al., 2001 & Fiamingo et al., 2005).
Mao et al., (1992) described a unilocular and was lined with cuboidal epithelium in a 35-yr-old woman was presented to the hospital because of nausea 20-30 min after eating, associated with weight loss. A CT scan revealed a cystic lesion in the neck of the pancreas. At operation, a 3-cm diameter cyst was excised from the pancreas. They stated that the natural history of this lesion is unknown as only four previous case reports of unilocular true cysts in adults have been reported in the English literature at that time.
Takahashi and his collegues (2001) described a 50 yr old woman presented with a mass lesion in the right upper quadrant of the abdomen. Abdominal computed tomography showed a cystic lesion, with a maximum diameter of 12 cm, between the inferior surface of the liver and the ascending colon. The cyst was homogenous and had smooth edges.
On magnetic resonance imaging, a unilocular cyst was seen. No connection between the cyst and the pancreatic ductal system was demonstrated on endoscopic retrograde cholangiopancreatography. Laparotomy was and on pathologic examination, the cyst was serous and was lined with a single layer of normal cuboidal epithelium.
Also, Fiamingo et al., (2005) reported a case of a true solitary cyst of the pancreas in a 26-year old woman. Abdominal magnetic resonance imaging and computed tomography showed a unilocular neoformation in the head of the pancreas, without obstruction of Wirsung's duct. The cyst was excised and histologically it was lined by cuboidal epithelium. They stated that only 11 cases of solitary true cyst of the pancreas in adults have been reported. They proposed a scheme for the differential diagnosis of cystic neoformations of the pancreas, starting from the histopathological definition of a true solitary cyst.
We report magnetic resonance imaging features of a case of congenital true pancreatic cyst with a high level of enzymatic activity which, to the best of our knowledge, have not previously been reported. A five years-old girl was admitted to Department of Surgery with a history of abdominal swelling for one month. A mobile, smooth, non-tender cystic mass was palpated on the left side of the abdomen and epigastric region during physical examination. Ultrasonography and CT imaging revealed a unilocular cystic mass sized 9.14 x 8 x 7.7 cm (Fig. 1).
MRI revealed a unilocular cystic mass reaching to anterior abdominal wall of the same size (Fig. 2).
During abdominal surgical exploration, the cystic mass is pushing the stomach superiorly and the left kidney was displaced posteriorly. Obliteration of the peripancreatic fat planes between the cystic mass and tail of the pancreas was observed. (Fig. 3, 4)
Dissection of the cyst from surrounding organs could not be completely achieved as the cyst wall was adherent to the posterior wall of the stomach (Fig 5, 6). Partial excision and marsupalization was performed (Fig 7).
The histopathology report revealed cyst lined by glandular epithelium and surrounded by pancreatic tissue. This finding was consistent with true pancreatic cyst (Fig 8).
Conclusion:
1- Although it is extremely rare in children, congenital true pancreatic cysts should be diagnostically considered in cases involving a cystic mass neighboring the pancreas.
2- The differential diagnosis of solitary true cyst from other cystic lesion of the pancreas usually is based on histology.
3- Particular care must be taken to distinguish this lesion from macrocystic serous cystadenoma.