giovedì 15 febbraio 2007

Benign lymphoepithelial cysts of parotid glands in HIV






Findings


Figure 1: Lateral scout image of CT scan showing the large soft tissue mass in the neck.
Figure 2 and Figure 3: Showing multiple variable sized thin walled cystic lesions in both parotid glands. Mild lymphoid hypertrophy at the base of the tongue is seen.

Differential diagnosis:
- Benign lymphoepithelial cysts of parotid glands in HIV
- Bilateral Warthin’s tumors
- Sjogren’s syndrome
- Bilateral cystic pleomorphic adenomas
- Necrotic intraparotid lymph nodes or lymphoma post-treatment
- Bilateral first branchial cleft cysts (intraparotid)


Diagnosis: Benign lymphoepithelial cysts of parotid glands in HIV


Benign lymphoepithelial cysts (BLC) of the parotid gland have been reported to occur in up to 5% of patients infected with HIV. HIV testing is recommended in patients with BLC since this can often be the initial presentation of the patient’s HIV status. A point of note is that BLC can occur before seroconversion so patients who initially test negative with BLC should be re-tested after 6-8 weeks. The exact pathogenesis of BLC is unclear but it is hypothesized that the cystic dilation and squamous metaplasia is caused by obstruction of the small intraparotid ducts by hyperplastic lymphoid tissue of the parotid lymph nodes. BLC are similar histologically to salivary duct cysts with the exception that BLC have dense lymphoid tissue within the cystic wall.

When present in patients without HIV, BLC usually presents as a unilateral cystic mass in patients in the 4th or 5th decade. In HIV positive patients the lesions are usually bilateral with associated findings of diffuse cervical lymphadenopathy and prominent adenoid and tonsillar tissue. The differential diagnosis in these patients includes bilateral Warthin’s tumors, Sjogren’s syndrome, bilateral cystic pleomorphic adenomas, necrotic intraparotid lymph nodes or lymphoma post-treatment and bilateral first branchial cleft cysts (intraparotid). BLC display characteristics of thin-walled cysts by CT and follow CSF signal characteristics on MR imaging.

The lesions of BLC are usually self-limited but surgical resection is an option in BLC for cosmetic purposes. Alternate methods of treatment include: cyst enucleation, low-dose radiation, sclerotherapy with doxycycline, antiretroviral therapy although all of these methods are associated with recurrence. There is a small risk of malignant transformation of benign lymphoepithelial cysts to lymphoma.

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