What is a lymphoepithelial cyst?

September 21, 2025 •

5 min read

While most bumps or swellings are harmless, a lymphoepithelial cyst (LEC) is a rare, benign lesion that can appear in various parts of the body. These slow-growing growths are characterized by a cystic cavity surrounded by lymphoid tissue, and they most commonly affect areas in the head and neck. Understanding the specifics of this condition is crucial for proper diagnosis and management.

Quick Summary

A lymphoepithelial cyst is a benign, slow-growing, encapsulated lesion formed by epithelial remnants trapped within lymphoid tissue. Often appearing as a painless swelling, they commonly occur in the head and neck, such as the parotid or submandibular salivary glands. Diagnosis requires imaging and a biopsy to confirm it isn't a more serious condition, and treatment typically involves surgical removal.

Key Points

Benign vs. Malignant: A lymphoepithelial cyst is a non-cancerous growth, but it must be properly diagnosed to rule out more serious conditions, such as lymphoma.
Common Locations: The cysts most frequently appear in the head and neck region, particularly within or near the parotid gland, submandibular gland, and lymph nodes.
HIV Connection: These cysts are a common manifestation of HIV, where they often appear as multiple, bilateral growths in the parotid glands.
Diagnostic Path: A definitive diagnosis typically involves imaging (ultrasound, CT, MRI) followed by fine-needle aspiration or surgical biopsy for histopathological analysis.
Treatment Options: Management ranges from conservative observation for small, asymptomatic cysts to definitive surgical excision for symptomatic or large lesions.
Embryonic Origin: One accepted theory for their development is the entrapment of epithelial cells within lymphoid tissue during embryonic development.

Understanding the Anatomy: What Are These Cysts?

A lymphoepithelial cyst (LEC) is a non-cancerous, encapsulated mass that is filled with a viscous, yellowish, keratinous material. The key characteristic is its unique structure: a cyst wall lined by epithelial cells, surrounded by lymphoid tissue. The most common locations for these cysts are the salivary glands, particularly the parotid gland, and the lymph nodes in the lateral neck. Oral LECs are also common and are often found on the floor of the mouth or on the lateral side of the tongue.

Where Do Lymphoepithelial Cysts Come From?

The precise origin, or pathogenesis, of lymphoepithelial cysts can vary depending on the location. Several theories have been proposed to explain their development:

Embryological Remnants: One theory suggests that LECs are a type of developmental cyst arising from misplaced embryonic remnants of the branchial arches that become trapped within lymphoid tissue during fetal development. This would explain their common location in the neck and salivary glands.
Ductal Obstruction: Another theory proposes that LECs form from cystic dilation of ducts within salivary glands or intraparotid lymph nodes. Lymphoid hyperplasia, or an overgrowth of lymphoid tissue, can cause a partial obstruction of a salivary duct, leading to a build-up of fluid and the formation of a cyst.
HIV-Associated: A specific type of LEC is strongly associated with Human Immunodeficiency Virus (HIV) infection. In HIV-positive individuals, the virus can trigger lymphoid hyperplasia within the salivary gland lymph nodes, leading to cyst formation. These cysts are often bilateral and multi-loculated, differing from the typically unilateral cysts found in immunocompetent patients.

Symptoms and Diagnosis: How Are They Detected?

For many patients, a lymphoepithelial cyst presents as a painless, slow-growing mass. The size can range from small to large enough to cause visible swelling and cosmetic deformity. Other symptoms depend on the cyst's location:

Head and Neck: Cysts in the parotid or submandibular glands may present as a swelling in the cheek or under the jaw. Oral LECs might be noticed as a whitish-yellow, firm, or soft nodule in the mouth.
Pancreas: Pancreatic LECs are extremely rare and are often found incidentally during imaging for other conditions. When symptomatic, they can cause nonspecific abdominal pain.

Diagnostic Tools

Because LECs can mimic more serious conditions, a definitive diagnosis relies on a combination of medical history, physical examination, and advanced imaging. The primary diagnostic tools include:

Imaging: Ultrasounds, CT scans, and MRIs can help determine the cyst's size, location, and relationship to surrounding structures. Multi-loculated cysts and associated lymph node enlargement on imaging can be suggestive of HIV-associated disease.
Fine-Needle Aspiration (FNA): A minimally invasive procedure where a sample of fluid is drawn from the cyst. The fluid may be thick and yellowish due to its keratin content. The FNA sample is then examined to rule out malignancy.
Histopathological Examination: The gold standard for diagnosis. After surgical excision, the entire cyst is sent to a pathologist for microscopic evaluation, which confirms the benign nature of the lesion and its characteristic lymphoepithelial structure.

Comparison: Lymphoepithelial Cyst vs. Other Conditions

It's important to distinguish LECs from other cystic lesions and potential malignancies. The table below highlights some key differences, particularly for head and neck lesions where LECs are most common.


Feature	Lymphoepithelial Cyst	Sebaceous Cyst / Epidermoid Cyst	Warthin's Tumor	Lymphoma
Origin	Epithelial remnants trapped in lymphoid tissue.	Proliferation of epidermal cells within the dermis.	Benign salivary gland tumor with lymphoid tissue and epithelial cells.	Malignant tumor of lymphoid cells.
Associated with HIV?	Often, especially bilateral cysts in the parotid gland.	No direct association with HIV.	Not directly linked, more common in older men.	Higher incidence in HIV patients, especially if BLECs are present.
Malignant Potential?	Very low to none, but long-standing cysts may have a slightly increased risk of developing into lymphoma.	Benign, very low risk of malignancy.	Benign, very low risk of malignancy.	Malignant, requires aggressive treatment.
Microscopic Finding	Cyst lined by squamous epithelium, surrounded by dense lymphoid tissue.	Cyst wall lined by stratified squamous epithelium without lymphoid tissue.	Papillary projections and bilayered oncocytic epithelium within a lymphoid stroma.	Proliferation of malignant lymphoid cells.
Treatment	Primarily surgical excision.	Excision is the primary treatment.	Surgical removal.	Chemotherapy, radiation, or a combination.

Treatment Options: From Observation to Surgery

The management of a lymphoepithelial cyst is guided by several factors, including its size, location, symptoms, and potential association with underlying systemic conditions like HIV.

Observation: For small, asymptomatic cysts where the diagnosis is certain, a “watchful waiting” approach may be recommended. This involves regular monitoring to ensure the cyst does not grow or cause problems.
Fine-Needle Aspiration (FNA): While FNA is often used for diagnosis, it can also be a temporary therapeutic measure to drain the cyst fluid. However, recurrence is very common with aspiration alone.
Sclerotherapy: This procedure involves injecting a sclerosing agent into the cyst to induce an inflammatory reaction that leads to its collapse and fibrosis. It is an alternative to surgery for some patients, particularly in HIV-associated cases.
Surgical Excision: Complete surgical removal of the cyst is often the gold standard for definitive treatment. This approach is curative and provides the tissue needed for final histopathological confirmation. For cysts in the parotid gland, a partial parotidectomy might be necessary.
HIV Management: For patients with HIV-associated lymphoepithelial cysts, initiating or optimizing highly active antiretroviral therapy (HAART) can cause the cysts to shrink or resolve. Surgical intervention may still be required for large, disfiguring, or persistently symptomatic cysts.

Conclusion: Navigating a Diagnosis

A lymphoepithelial cyst is a benign condition, but its diagnosis and management can be complex due to its varied locations and potential associations with systemic diseases. While often a painless swelling in the head and neck, its appearance can be similar to more serious conditions, necessitating a thorough diagnostic workup. From watchful waiting to definitive surgical excision, several treatment strategies are available. For a definitive diagnosis and to discuss the best course of action, patients should consult with a healthcare professional, often an ENT specialist or oral surgeon, to review all imaging and biopsy findings. Staying informed about your health conditions is the first step toward effective management. For more general health information, visit the Centers for Disease Control and Prevention website at https://www.cdc.gov/.

Frequently Asked Questions

A lymphoepithelial cyst is sometimes referred to as a branchial cleft cyst, particularly when located in the lateral neck. While the two terms can be used interchangeably in some contexts, the distinction lies in whether the cyst arises from trapped embryonic branchial cleft remnants or from salivary gland epithelium caught in lymphoid tissue. A pathologist's review is required for a definitive classification.

Most lymphoepithelial cysts are asymptomatic and painless, presenting only as a slow-growing swelling or mass. However, if the cyst becomes infected, it can cause pain, tenderness, and inflammation.

Recurrence is uncommon after a complete surgical excision. However, some minimally invasive treatments like aspiration may have a high recurrence rate. In HIV-associated cases, new cysts may develop over time due to the underlying systemic condition.

You should start by seeing your primary care physician, who will likely refer you to a specialist such as an otolaryngologist (ENT doctor), oral and maxillofacial surgeon, or a general surgeon, depending on the location of the cyst.

Diagnosis of a pancreatic lymphoepithelial cyst can be challenging before surgery. They are often discovered incidentally during imaging like CT or MRI for other reasons. A definitive diagnosis typically requires histopathological examination of the cyst wall after surgical resection.

Yes, benign lymphoepithelial cysts (BLECs) in the parotid glands are a common manifestation of HIV infection, sometimes serving as the first clinical sign. For this reason, HIV testing may be recommended for patients diagnosed with these cysts.

Yes, non-surgical treatments include watchful waiting for small, asymptomatic cysts. Aspiration can provide temporary relief, but recurrence is common. Sclerotherapy, which involves injecting an agent to induce scarring, is another option, particularly for HIV-associated cysts.