Benign lymphoepithelial cysts (BLECs) are one of the most common causes of bilateral parotid gland enlargement in HIV-positive patients and are a component of AIDS-associated salivary gland disease (HIV-SGD). They are cystic lesions developing on the background of reactive lymphoid hyperplasia of intraparotid lymph nodes within the parotid gland. Histologically, they are cysts containing lymphoid tissue surrounded by lymphoepithelial epithelium. With a prevalence of 3-6% in HIV+ population, they may be the first manifestation of AIDS in some patients. The combination of bilateral, multiple, well-defined cystic lesions + diffuse cervical lymphadenopathy is nearly pathognomonic for HIV-SGD. Significant regression is seen with antiretroviral therapy (ART). On imaging, multiple, well-defined, cystic lesions in bilateral parotid glands and bilateral cervical reactive lymphadenopathy are diagnostic. T2 hyperintense cysts on MRI and hypodense cystic lesions on CT are seen; they show no enhancement. Presence of solid component should raise suspicion for lymphoma transformation.
Age Range
20-50
Peak Age
35
Gender
Male predominant
Prevalence
Uncommon
The pathophysiology of benign lymphoepithelial cysts is directly related to the immunological consequences of HIV infection. HIV virus infects intraparotid lymph nodes within the parotid gland, and reactive lymphoid hyperplasia (follicular hyperplasia) develops. Hyperplastic lymphoid tissue mechanically obstructs parotid ductules, and salivary retention leads to cyst formation. Simultaneously, invasion of lymphoid tissue into epithelial ductules creates the 'lymphoepithelial' cyst structure. Bilateral involvement results from HIV being a systemic immunological disease — all intraparotid lymph nodes are affected. On imaging, T2 hyperintensity of cysts reflects high free water content (mucinous secretion accumulation). The thin cyst wall without enhancement indicates that the wall consists of epithelial structure rather than active inflammation. Cervical lymphadenopathy is another reflection of HIV's systemic lymphoid activation. With ART, decreased viral load and immune system restoration lead to regression of lymphoid hyperplasia and consequently cyst shrinkage.
Combination of multiple, well-defined, T2 hyperintense cysts in bilateral parotid glands + bilateral cervical lymphadenopathy is nearly pathognomonic for HIV-related benign lymphoepithelial cysts.
T2-weighted MRI shows multiple, well-defined, markedly hyperintense cystic lesions in bilateral parotid glands. Cyst sizes are variable (from a few mm to several cm). Cyst content is homogeneously hyperintense — slight signal variations may exist depending on protein content. Parotid parenchyma between cysts may be normal or mildly enlarged. This bilateral, multiple cystic pattern is nearly pathognomonic for HIV-SGD.
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Multiple, well-defined cystic lesions demonstrating marked hyperintense signal on T2-weighted sequences are identified in both parotid glands; consistent with HIV-related benign lymphoepithelial cysts.
Contrast-enhanced CT shows multiple, well-defined, hypodense (fluid density, 0-20 HU) cystic lesions in bilateral parotid glands. The cyst wall is thin and regular; shows no enhancement or very mild rim enhancement. Parotid glands may be diffusely enlarged. Multiple reactive lymph nodes accompany in bilateral cervical regions.
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Multiple well-defined hypodense cystic lesions of fluid density are identified in both parotid glands; bilateral cervical lymphadenopathy accompanies.
B-mode US shows multiple, well-defined, anechoic or low internal echo cystic lesions in bilateral parotid glands. Posterior acoustic enhancement confirms cystic nature. Thin septa may be visible. Parotid parenchyma between cysts may appear normal or diffusely heterogeneous.
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Multiple, well-defined, anechoic cystic lesions with posterior acoustic enhancement are identified in both parotid glands.
On T1-weighted sequences, cysts are generally hypointense (simple fluid). T1 signal may increase in cysts with high protein content (mild hyperintensity). Cyst content shows no enhancement on post-contrast series — confirming simple cystic nature.
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Cysts demonstrate hypointense signal on T1-weighted sequences with no enhancement on post-contrast series.
Multiple reactive lymph nodes accompany in bilateral cervical regions. Lymph nodes are generally regular-bordered, oval, homogeneous density, and <2 cm. No central necrosis (necrosis should suggest tuberculosis or lymphoma). Lymph nodes may show enhancement.
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Multiple reactive lymphadenopathy is identified in bilateral cervical regions.
On diffusion-weighted imaging, lymphoepithelial cysts show no true diffusion restriction — ADC values are high (>2.0 × 10⁻³ mm²/s). This finding is of critical importance in differentiation from infected cyst or abscess: abscess ADC is <0.7 × 10⁻³ mm²/s while simple cystic lesions have ADC >2.0. T2 shine-through may create increased signal on DWI at high b-values; correlation with ADC maps is therefore mandatory. If solid component develops, detection of diffusion restriction should suggest lymphoma transformation.
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No true diffusion restriction is detected in cystic lesions, with high ADC values; these findings are consistent with simple cystic content and exclude abscess/lymphoma transformation.
Criteria
Thin-walled, non-septated, homogeneous cystic
Distinct Features
Simple cyst appearance, prominent posterior enhancement
Criteria
Internal septa, debris, thick wall
Distinct Features
Septa and debris create internal echogenicities
Criteria
>4 cm, cosmetic deformity
Distinct Features
Prominent parotid enlargement, facial asymmetry
Distinguishing Feature
Sjögren shows 'leopard skin' pattern (small hypoechoic areas), not well-defined cysts; HIV test is negative
Distinguishing Feature
Warthin tumor is usually single or bifocal, contains solid component, has T2 hypointense solid areas
Distinguishing Feature
In lymphoma, solid mass is dominant, shows marked diffusion restriction, cystic lesions are minimal
Urgency
routineManagement
medicalBiopsy
Not NeededFollow-up
6-monthAntiretroviral therapy (ART) is the primary approach — regression of lesions is expected with viral load control. Aspiration or parotidectomy may be considered for large cysts causing cosmetic concerns. Development of solid component should be monitored for lymphoma transformation.
Antiretroviral therapy is the primary approach. Regression expected with treatment. Aspiration or parotidectomy may be considered for cosmetic concerns.