1. Lymphoepithelial Cyst with Sebaceous Differentiation (Sebaceous Lymphadenoma) of the Pancreas, Dermoid Cyst or Not ? - A Case Report and Review of Literatures
Dae Kyum Kim, Sang Ik Noh, Jin Seok Heo, Jae Hyung Noh,Tae Sung Sohn, Seong Ho Choi, Yong Il Kim, GeungHwan Ahn*
Department of Surgery and Diagnostic Pathology*, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, Korea
Introduction
4. Pathologic Findings
‘lymphoepithelial cyst’ for these interesting cyst.
Classification
Cystic lesions of the pancreas can be histologically classified into several categories including pseudocyst, congenital true cyst, acquired true cyst, and cystic neoplasm. True cysts are characterized by epithelial lining, in which there are 3 types of morphologically similar lesions that may presents as ‘squamous cysts’; LECs, dermoid cysts, and accessory-splenic epidermoid cysts.
Differential diagnosis in the squamous lined cysts
LECs are seen predominantly in men and in adulthood (mean age, 56 years). They may occur at any site of the pancreas. LECs may be multilocular or unilocular, and are characterized by stratified squamous epithelium surrounded by dense lymphoid tissue such as germinal centers.
Dermoid cysts occur in younger age group (mean age, 23 years), and there is no gender prominence. Mucinous epithelium, respiratory type mucosa, and sebaceous units are more readily identifiable, and they may contain hair follicles. Subepithelial lymphoid tissue is not a feature.
Accessory-splenic epidermoid cysts tend to be detected at an younger group (mean age, 37 years) than LESs. There is no gender prominence and microscopically, the presence of splenic red pulp is diagnostic.
LEC with sebaceous differentiation (LECSD)
LECSD was described by Fitko and co-workers in Like our case, the possibility of a dermoid cyst was considered because of presence of sebaceous glands. However, it is precluded by lack of hair follicles and sweat gland and the presence of dense lymphoid tissue. LECSD has been also reported in other organs, such as skin and salivary gland. That may be owing to multipotentiality of germinative cells of squamous epithelium.
Pathogenesis
The histopathogenesis of LECs is unclear. There are four proposed mechanisms.
1. Development from epithelium remnants in lymph node.
2. Squamous metaplasia in the pancreatic duct that undergo cystic transformation.
3. Some form of teratoma
4. Development from misplaced brachial cleft tissue.
Treatment
Surgical resection is only treatment. LECs can be cured completely by resection. As previously described, surgery is important to identification and early removal of pancreatic cystic neoplasm.
Gross examination (Fig.2)
A unilocular cyst measured 3X2X2 cm in greatest dimension and contained bright yellow cheesy, greasy tiny oval materials and whitish keratin. The wall was relatively rough. No communication with pancreatic duct was found.
Lymphoepithelial cysts (LECs) of the pancreas are rare, with the literature containing only 40 documented examples of this entity, which are distinctive lesions characterized by the presence of a mature, keratinizing squamous lining surrounded by lymphoid tissue. Among these rare cysts, the case with sebaceous differentiation, so-called unilocular cystic sebaceous lymphadenoma is extremely rare. Sebaceous differentiation is not revealed usually in LECs, so that it may be confused with dermoid cyst that usually shows sebaceous differentiation . We have experienced this rare cyst and review it in surgico-pathological aspect.
Mass
Case
Pancreas
Spleen
1.Brief History
Fig.2 Gross finding. The cyst was unilocular
A 70 year-old man presented with a two month history of postprandial upper abdominal pain. He had a history of heavy alcoholic drinking while he was young but had no history of abdominal trauma. Physical examination showed right upper quadrant tenderness. Chest X-ray, EKG, and laboratory data including cardiac and pancreatic enzymes were normal. On an ultrasonographic study showed multiple hepatic simple cysts and mild pancreatic ductal dilatation. CT and ERCP were performed.
Microscopic examination (Fig.3)
The wall was lined by keratinising squamous epithelium which was surrounded by dense lymphoid tissue with germinal centers. A few clusters of well-formed sebaceous glands were found beneath the squamous epithelium. There was no hair follicle and sweat grand. On immunohistochemical staining, the epithelial lining was positive on keratin stain, inner epithelial cell contained PAS, D-PAS and mucicamine positive material.
2. Radiologic Findings
CT finding (Fig. 1, Left)
A 2.7 cm sized protruding cystic mass with low density was revealed in the tail of the pancreas. There was no definite solid portion in the mass but internal enhancing septa were showed. Pancreatic cystic neoplasm was suggested. In liver, multiple simple cysts were identified.
ERCP finding (Fig. 1,Right)
Pancreatic duct was normal.
Germinal centers
Squamous epithelium
Sebaceous gland
Fig. 3 Microscopic findings. Dense germinal centers and squamous epithelium, H & E X50 (Left). Sebaceous differentiation, H & E X100 (Right).
Liver cyst
Mass
5. Postoperative course
The patient was discharged on 9th postoperative day. He was followed up 12-month postoperatively and no recurrence was noted.
Pancreatic duct
Discussion
Fig. 1 CT and ERCP findings
Conclusion
History
Lymphoepithelial cyst(LEC) of the pancreas is one of the cysts that are recently described as a disease entity. In 1985, Luchtrath and Schriefers described a multilocular cyst of the pancreas histologically similar to the so called branchiogenic cysts that occur in the neck. In 1987, Truong and co-workers proposed the name
3. Operation
A laparotomy was performed with impression of pancreatic cystic neoplasm. In the tail of the pancreas, 3 cm sized protruding cystic mass was found. The cyst was unilocular and there was no infiltration. Distal pancreatectomy was performed.
LECSD is curable with surgical resection.
It is extremely rare but may be considered a distinct entity in the cystic lesions of the pancreas.