Description:
A 67-year-old male presented with left upper quadrant abdominal pain of one month duration. A CT scan showed a 3 cm cystic lesion with internal fat content arising from the tail of pancreas. The CA 19-9 level was within normal reference range at 8.4 U/mL. Patient was referred to our institution for further evaluation with endoscopic ultrasound.
On endoscopic ultrasound, the pancreatic duct was normal caliber and measured 2.5mm in diameter. There was a 37mm x 19 mm heterogeneous mass visualized in the pancreatic tail. An intact tissue plane was present between the mass and the gastric muscularis propria. Within the lesion, there were round and hyperechoic globules and an eccentric hyperechoic region measuring 20 mm x 13 mm. EUS guided transgastric FNA was performed of the pancreatic tail mass with a 19-gauge needle. The specimen was sent for cytological analysis.
Cytology was negative for malignant cells. There was acellular proteinaceous debris surrounded by a lymphocytic rim and epithelium. Fat droplets were seen within the lymphocytic rim. The cyst contents under diff-quik and pap stain showed anucleated cells in concentric arrangement. The differential diagnosis for this cytology included lymphoepithelial cyst, pseudo cyst or benign cystic teratoma.
Due to ongoing abdominal pain, we elected for a laparoscopic removal of the pancreatic cyst. After careful dissection into the lesser sac, the cyst was visualized near the posterior wall of the stomach originating from the pancreatic tail. The cyst was completely separate from the stomach. The cyst was dissected free from the surrounding fatty tissue and removed en bloc by hand assist. There were no postoperative complications and the patient made a complete recovery.
On gross description, it was a brown-tan cystic structure with multiple yellow-firm nodules arising from the inner part of the cyst wall. Microscopic pathology of the surgical specimen showed the cyst wall lined with squamous epithelium with foci of sebaceous differentiation. Abundant lymphocytes were also noted in the wall. These findings were consistent with the diagnosis of lymphoepithelial cyst of pancreas.
Discussion:
Pancreatic lymphoepithelial cyst is a rare benign cyst seen mostly in middle aged males (M: F=4:1)1. It is considered a true cyst due to the epithelial lining on the cyst wall. They are mostly asymptomatic or cause nonspecific symptoms. 40-50% of these cysts are found incidentally at autopsy or imaging.
FNA is typically the first diagnostic modality which could confirm the benign nature of the lesion. The diagnostic accuracy of EUS-FNA or criteria for cytological diagnosis2 has not been validated due to the rarity of presentation. On EUS, the appearance can be cystic, solid or a mixture of both. The cyst cavity could be uniloculated or multiloculated with hyperechoic areas inside the cyst cavity3. On cytological analysis the cyst wall is made of squamous epithelium, mature lymphocytes and multinucleated giant cells. The cyst contents have abundant anucleated squamous epithelium, keratinous debris and cholesterol crystals3, 4. The presence of acellular squamous epithelium in the cyst contents is the characteristic feature for lymphoepithelial cyst.
Even though lymphoepithelial cysts are benign with no malignant transformation potential, there could be diagnostic difficulty differentiating it from cystic neoplasm of the pancreas. In these difficult and symptomatic cases, surgery is the definitive treatment.
References:
1. Adsay NV, Hasteh F, Kloppel G, et al. Lymphoepithelial cysts of the pancreas: A report of 12 cases and a review of the literature. Mod Pathol 2002; 15:492-501.
2. Sushil K Ahlawat. Lymphoepithelial Cyst of Pancreas. Role of Endoscopic Ultrasound Guided Fine Needle Aspiration. J Pancreas (Online) 2008; 9(2):230-234.
3. Nasr J, Sanders M, McGrath K, etal. Lymphoepithelial cysts of the pancreas: An EUS case series. Gastrointest Endosc. 2008; (1):170-3.
4. Liu J, Shin HJ, Staerkel GA, et al. Cytologic features of lymphoepithelial cyst of the pancreas: two preoperative diagnosed cases based on fine needle aspiration. Diagn Cytopathol. 1999; (5):346-50.
Disclosures:
The authors have no conflict of interest or financial disclosures to be made with regards to this project. This project has not received any financial aid or funding of any kind for its making
Contributed By:
Sandeep T. Samuel, MD, University at Buffalo, Buffalo, NY
Neil Wilkinson, MD, Roswell Park Cancer Institute, Buffalo, NY
Kanheira Kazunouri, MD, Roswell Park Cancer Institute, Buffalo, NY
Andrew J. Bain, MD, Roswell Park Cancer Institute, Buffalo, NY
