Nodal inclusion cysts of the parotid gland and parapharyngeal space: a discussion of lymphoepithelial, AIDS-related parotid, and branchial cysts, cystic Warthin's tumors, and cysts in Sjögren's syndrome.

The purpose of this report is to examine the computed tomography scans, magnetic resonance images, and pathologic findings in 44 patients, 42 of whom had inclusion-type cysts of the parotid and parapharyngeal space of varying etiologies. Two additional cases of cystic changes in the benign lymphoepithelial lesion (BLEL) of Sjögren's syndrome are highlighted here, since they had unusually large cystic components mimicking acquired immunodeficiency syndrome-related parotid cysts (ARPCs). A retrospective examination identified 18 ARPCs, 3 lymphoepithelial cysts (LECs), 13 cystic Warthin's tumors, 8 branchial cysts, and 2 cases of cysts in patients with Sjögren's syndrome (BLEL), all of whom had imaging studies and pathologic confirmation. There were 30 men and 14 women with an age range of 25 to 72 years (median, 46.82 years). Any similarities in the imaging appearances were noted, as were any differences in pathologic detail. On imaging, only the cystic Warthin's tumors had any focal wall nodularity; the other cysts had smooth walls. When multiple parotid cysts were present, the distinguishing feature between ARPCs and cysts in BLEL (and some cystic Warthin's tumors) was the presence of diffuse cervical adenopathy in patients with ARPCs. Imaging usually could not differentiate between a solitary parotid LEC, a branchial cyst, and some cystic Warthin's tumors. Extraparotid lesions were either branchial cysts or cystic Warthin's tumors. Physicians should be aware of the variety of different inclusion-type cysts that may occur in the parotid gland and parapharyngeal space, all of which may have similar imaging appearances. Although imaging clearly identifies these cysts and may suggest a specific diagnosis, it must always be remembered that the precise diagnosis remains in the province of the pathologist.