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Recently, cystic parotid enlargements have been reported in the medical literature as a new manifestation of HIV3. Parotid enlargements have been frequently found in pediatric AIDS patients4 in approximately 30% of the cases. Parotid enlargements, although of cardinal importance to the stomatologist, likewise are accompanied by systemic further symptomatology. A comprehensive physical examination reveals that these patients also develop an increase in CD8 T-cells and a diffuse infiltrative lymphocytic sydrome (DILS).
A case report from the Salivary Gland Clinic, Columbia University School of Dental and Oral Surgery, is presented in an attempt to describe the salient characteristics of HIV parotitis. A review of the diagnostic aspects, pathogenesis and prognosis will also be discussed.
The patient's guardian did not note any fluctuation in the size of the swelling. Intraorally, the mucosa was moist, and the ducts were patent producing a free and adequate salivary flow. There was no evidence of mucosal inflammation. The child presented with bilateral parotid swelling, with the left side larger than the right (fig. 1).
Figure 1: Bilateral parotid swellings. Note the marked swelling on the left.
Palpation elicited no pain. The enlargements were soft, with a consistency that indicated the presence of contained fluid. Labial gland biopsy revealed a marked lymphocytic infiltrate. A CD4/CD8 cell study corroborated an increase in CD8 T-cells.
Imaging techniques such as ultrasound and computerized tomography revealed the presence of multiple cysts of various sizes in both glands. The left parotid gland presented with one large cyst and several smaller ones, while the right parotid revealed several small cysts.
A chest x-ray presented with a classic cloudy, honeycomb appearance diagnostic for lymphocytic interstitial pneumonitis, an aspect of DILS.
As reported, the parotid cysts are painless and slow growing, with no history of any fluctuation in size. The parotids normally are affected bilaterally with occasional reports of unilateral swellings. Regardless, when the glands are examined via imaging modalities, bilateral gland involvement is customarily detected.7 In addition, the lesions are usually multicystic and range in size from 0.5 cm to as much as 5 cm in diameter. Usually only the superficial lobe is affected.8,9,10
The parotid glands begin to develop at 4 to 6 weeks of embryonic life. By five months in utero, the tubular components are formed and terminal clusters are differentiating into acini. The acini of the parotid are almost entirely serous. The secretory acini and smaller ducts successively merge into ducts of larger ducts until they merge into Stenson's duct. 11,12
The most substantial finding is that lymph nodes are frequently included within the capsule of the parotid during its development. During embryogenesis, 5 to 10 lymph nodes are trapped within the parotid, and with them are enveloped salivary gland acini and ducts. Unlike the parotid, the submandibular gland, which forms earlier than its adjacent lymph nodes, is devoid of lymph node inclusions; instead, the lymph nodes are found extraglandularly. Since lymphoidal tissue is vulnerable to the HIV virus, lymphoproliferative involvement of the intraparotid, perisubmancibular, perisublingual and cervical lymph nodes can be expected.13
What is rather peculiar about the DILS component of AIDS is the increase in CD8 T-cells. Unlike classical HIV where there is a concomitant decrease in both the CD4 and CD8 lymphocytes, patient's with HIV-related parotid cysts present with a classical decrease in CD4 cells, but with a substantial increase in CD8 cells14,15. A normal CD4 cell level ranges from 500 to 1500/ ml. Patients with parotid cysts and cervical lymphadenopathy usually have CD4 levels below 500/ml.16 CD8 levels for these same patients range 1300 - 3000/ml.
The pathogenesis of lymphoproliferative changes in the parotid remains unclear. The saliary epithelial components are randomly distributed throughout the lymphoid stroma. The proliferation comes as a result of a reactive process rather than a neoplastic process. The epithelial component consists of residual glandular acini and solid, cystic epithelial islands
containing a disorganized mixture of proliferating ductal epithelial and myoepithelial cells with characteristically elongated nuclei.17
Some authors claim that the epithelium plays a passive role, simply reacting to the hyperplastic lymphoid tissue that invades and distorts the normal salivary architecture. This in turn results in ductal and acinar changes. Others believe that the primary lesion is ductal with a secondary lymphoid response. Rauch et al18, provide strong evidence that benign lymphoepithelial lesions represent an exaggerated immunological response to an infection. It has been further suggested by Itescu that the proliferation of parotid parenchyma is initiated by cytokine secretion.19
Ultrasound can serve as a simple and useful technique for diagnosis of HIV-related lymphoepithelial cysts. Solid and cystic changes are readily and satisfactorily identified. Apart from this, ultrasonography is a quick, available and inexpensive modality.
In this reported case, the ultrasound study showed an area 2 x 3 cm in the left parotid gland (fig. 2),with hypoechoic lesions represent cysts and massive lymphocytic infiltrate. Cystic or fluid-filled lesions are echo free with an enhancement of the deep wall. Benign lymphoepithelial masses are typically less echogenic than parenchyma, more sharply defined and of homogeneous echo strength and density.
Figure 2: Ultrasound study shows a large anaechoic lesion that
represents a cyst within the left parotid gland.
In computerized tomography, cystic lesions typically appear as well circumscribed, low-density areas. CT scans are useful in evaluating structures in, and adjacent to the salivary glands. The technique aids in contrasting hard from soft tissue, as well as, minute differences in soft tissue densities. As shown, the parotids are more radiodense than the surrounding fat but less dense than the adjacent muscles (fig. 3).
Figure 3: A CT SCAN of a patient with cystic masses.
CT images of cysts and mucoceles demonstrate well-circumscribed margins and thin walls. The radiographic density of the lumen may vary, depending on the composition of the fluid contained therein.
A biopsy taken from labial salivary glands showed an extensive lymphocytic infiltrate. Findings included florid lymphocytic infiltration almost completely replacing the parotid parenchyma and focal germinal center formation (fig 4). These observations histologically closely resemble benign lymphoepithelial lesions (BLL). A CD4/CD8 count corroborated the presence of CD8 T-cells.
Figure 4: Histology of the Lemphoepith cyst.
Special thanks are extended to Dr. L. Mandel, Dr. Pulse and Dr. D. Zegarelli for their assistance, patience and mentoring.
3.Sperling N, Lin P, Lucente F (1990) Cystic Parotid Masses in HIV Infection. Head &;Neck 12:337-341
4.Sperling et al. (1990) (See Ref. 3)
7.Mandel et al. (1992) (See Ref. 5)
11.Rankow RM, Polayes IM (1976) Diseases of the Salivary Glands Pennsylvania: WB Saunders
12.Goaz P, White S (1994) Oral Radiology: Principle and Interpretation 3rd edition. Missouri: Mosby-Year Book, Inc. pp. 681-9
13.Poletti A, Mancone R, Volpe R, Carbone A. (1988) Study of AIDS related lymphadenopathy in the intraparotid and perisubmaxillary gland lymph nodes. J of Oral Pathology 17:164-7
14.Ioachim H, Ryan J, Blaugrund S (1988) Salivary gland lymph nodes. Arch of Pathol Lab Med 112:1224-8
15.Ioachim H, Ryan J (1988) Salivary galnd lymphadenopathies with AIDS. Human Pathol 19:616-7
16.Sperling et al. (1990) (See Ref. 3)
17.Goaz et al. (1994) (See Ref. 12)
18.Rauch S, Seifert G, Gorlin RJ, (1970) Diseases of Salvary glands: Tumors (eds) Gorlin and Goldman. Thoma's Oral Pathology. Missouri: C. V. Mosby Co.
19.Itescu S, Brancato L, Buxbaum J, Gregersen P, Rizk C, Croxson TS, Solomon G, Winchester R (1990) A Diffuse Infiltrative CD8 Lyumphocytosis Syndrome in Human Immunodeficiency Virus (HIV) Infection: A Host Immune Response Associated with HLA DR5. Annals of Internal Medicine 112:3-10.