Lymphoepithelial cyst of Parotid

LYMPHOEPITHELIAL CYST OF PAROTID

• It is defined as cysts lined by epithelium with underlying stroma showing dense lymphoid aggregates

• It can be associated with HIV infection

Clinical features

• Site: presents in parotid or upper cervical lymph nodes

• Age: Most common in adults (peak age is from 2^nd to 4^th decade) but can occur in children also

• Sex: male predominance with male to female ratio of 7:1

• Clinical presentation: presents as firm compressible swelling which is unilateral and usually unicystic

• If associated with HIV – presents as bilateral parotid swelling accompanied by cervical lymphadenopathy

Etiopathogenesis

• Few theories have been proposed regarding its origin

  • Originates from remnants of embryonic branchial apparatus, similar to a branchial cleft cyst

  • Another theory is that they develop from cystic proliferation of salivary gland epithelium which is entrapped in intraparotid and paraparotid lymphnodes

  • It can be lymphocytic response to cyst as in reactive tumor associated lymphoid tissue that proliferates in salivary gland neoplasms  

Morphology

• Gross

• Uniloculated or multiloculated cyst (If associated with HIV)

• Solid, tan homogenous areas of the cyst wall and granular areas projecting into cyst lumen represent lymphoid tissue

• Microscopy

• Lymphoepithelial cysts have more irregular or undulating luminal surface when compared to salivary duct cyst

• Cyst wall is usually lined by squamous epithelium

• Other epithelium which can be seen are

  • Cuboidal epithelium

  • Columnar epithelium with goblet like cells

  • Pseudostratified ciliated columnar epithelium

• Beneath the epithelium, stroma shows dense lymphoid tissue with lymphoid follicles.

• Lymphocytes may infiltrate epithelium.

• Lymphoid tissue is well demarcated from surrounding salivary gland parenchyma

Differential diagnosis

• Warthin tumor – Cystic spaces with papillae lined by double layered epithelium i,e. tall-columnar cell which are oncocytic and basal layer. Lymphoid follicles are seen in stroma

• Salivary duct cyst : lined by stratified squamous epithelium. Goblet type mucinous or oncocytic cells may be present in epithelium. Stroma shows atrophic acini and chronic inflammatory cells

• Mucocele – mucinous material in cyst and fibrotic cyst wall is lined by cuboidal to stratified squamous epithelium.

• Polycystic disease of parotid – small epithelial cyst interspersed through out the parotid

 

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Cyst wall lined by metaplastic squamous epithelium. Sub epithelial tissue show lymphoid follicles. Adjacent foci shows benign acini (H&E,X50)