Benign lymphoepithelial lesions (BLL or BLEL), also misleadingly known as AIDS-related parotid cysts (ARPC), are mixed solid and cystic lesions that enlarge the parotid glands, and are usually associated with cervical lymph node enlargement, and nasopharyngeal lymphofollicular hyperplasia.
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Terminology
Benign lymphoepithelial lesions refer specifically to a histopathological finding that is non-specific and seen in the context of lymphoepithelial sialadenitis (typical of Sjögren syndrome) and HIV-associated salivary gland disease 5. This article focuses on the findings in the latter condition.
Epidemiology
Despite their aforementioned alternative name, benign lymphoepithelial lesions are seen usually in HIV-positive patients without AIDS and are not an AIDS-defining illness. It is relatively common in the HIV population, with 5% of patients eventually developing benign lymphoepithelial lesions.
Pathology
Thought to arise from dilatation of intraglandular ducts from obstruction due to lymphoid hypertrophy. They are bilateral in ~20% of cases.
Location
Benign lymphoepithelial lesions most commonly arise in the parotid gland and are only rarely seen in the submandibular glands or sublingual glands.
Radiographic features
- well-circumscribed cystic spaces
- may demonstrate thin rim enhancement on postcontrast MRI
- ultrasound demonstrates these 'cystic' lesions to actually have multiple small septations, and commonly also small mural nodules (40%)
- a vascular pedicle may be seen entering the cystic region
Benign lymphoepithelial lesions are usually seen associated with other sites of lymphoid hyperplasia 4, including:
- prominent nasopharyngeal adenoidal tissue: seen in 35% of HIV positive patients 4
- posterior triangle lymphadenopathy
- abnormal bone marrow signal
Differential diagnosis
On imaging consider
- first branchial cleft cyst
- Warthin tumor
- Sjogren syndrome
- sialocele
- sarcoidosis
- necrotic intraparotid lymph nodes
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