Diagnosis:
Lymphoepithelial cyst
• The differential diagnosis of a neck lesion containing lymphocytes includes Warthin’s tumor, lymphoepithelial cyst, benign lymphoepithelial lesion, intraparotid lymph node, chronic sialadenitis, and lymphoma. In cases lacking an epithelial component in the aspirated material, it may not be possible to distinguish a lymphoepithelial cyst from other benign entities.
• Benign lymphoepithelial cysts may be the result of duct obstruction from lymphoid hyperplasia or duct destruction related to cell-mediated immunity. There is an increased prevalence of lymphoepithelial cysts in parotid glands of HIV-positive patients. In these patients, the parotid cysts usually are multiple and bilateral. HIV infection should be suspected in patients with cystic parotid glands. Fine needle aspiration can be both diagnostic and therapeutic in these patients; the fluid may or may not recur.
• Benign lymphoepithelial cysts and Warthin’s tumors have overlapping features, and the distinction may be difficult in some cases. The oncocytic component in Warthin’s tumors may be scanty and squamous cells may even be present.
• The distinction between lymphoepithelial cysts and the benign lymphoepithelial lesion of Sjögren’s syndrome likewise can be difficult. Aspirates of benign lymphoepithelial lesions are usually more cellular than those of lymphoepithelial cysts. They have been reported to contain a polymorphous population of lymphocytes, histiocytes, myoepithelial cells, and ductal epithelial cells. In addition, tingible body macrophages and follicular center cell fragments may be seen. A major helpful diagnostic feature in the benign lymphoepithelial lesion is the presence of so-called epimyoepithelial island fragments. These are cellular aggregates composed of small lymphocytes intermixed with polygonal cells possessing abundant cytoplasm and large, oval nuclei that occasionally display distinct nucleoli.
• Sjögren’s syndrome is a complex of clinical symptoms that appears to be caused by an autoimmune destruction of exocrine glands (salivary and lacrimal). Benign lymphoepithelial lesions are often associated with Sjögren’s syndrome and other connective tissue diseases; other terms for this lesion include lymphoepithelial sialadenitis, myoepithelial sialadenitis, Sjögren’s type sialadenitis, and autoimmune sialadenitis. Malignant lymphoepithelial lesions of the salivary gland occur, but are rare tumors. The aspirates are comprised of malignant epithelial cells in a background of lymphocytes.
• Smears from intraparotid lymph nodes usually are highly cellular, containing a mixed population of lymphoid cells, tingible body macrophages, and follicular center cell fragments. Fragments of acinar tissue may be seen, but squamous epithelial cells are not present.
• In most cases of salivary gland nodules yielding a lymphoid infiltrate in fine needle aspiration material, careful examination of the lymphoid cell population, the background, and epithelial cells permits accurate diagnosis. When non-Hodgkin lymphoma is suspected based on cytologic findings, a sample should be sent for flow cytometric analysis.
