22
Salivary Glands and Rare Head and Neck Lesions
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Fig. 22.16 Cystadenolymphoma. Squamous cell metaplasia with distinct atypia ((A) May-Grünwald-Giemsa x MP); (B) Papanicolaou x MP).
material but are not easily seen in Papanicolaou-stained smears.
They are found in association with the sheets of oncocytic cells.
Mast cells may also occur, but less frequently, in mucoepider-
moid carcinoma and pleomorphic adenomas.32
Key features of adenolymphoma (Warthin's tumor)
Monolayered sheets of oncocytic cells with distinct
cell borders;
Thin cystic material to a granular amorphous sub-
stance;
Inflammatory cells and cellular debris; and
Mixed population of lymphocytes often in tissue
tangles.
An aspirate containing only fluid or mucoid material is obvi-
ously not diagnostic but raises the possibility of adenolym-
phoma if the aspiration is made in the parotid gland region.
Cystic, well-differentiated mucoepidermoid carcinomas may
also yield aspirates of abundant mucoid material containing
small clusters of epithelial cells with minimal nuclear atypia
and numerous lymphocytes. The epithelial cells in this case usu-
ally are superimposed and have a finely vacuolated cytoplasm, a
sign of mucous production. These cells do not usually appear in
monolayered sheets, and the cellular borders are indistinct.
Metaplastic epidermoid cells in adenolymphomas can be
atypical and even show true keratinization. They can, thus, be
confused with squamous carcinoma cells (Fig. 22.16). We there-
fore advocate that a conclusive diagnosis of a well-differentiated
squamous cell carcinoma in the parotid area should be made
only if a primary carcinoma can be found in the oral cavity or
upper respiratory tract.
Aspirates from
a predominantly solid adenolymphoma
with only a few lymphocytes may be indistinguishable from
oncocytoma. Distinction between these two neoplasms is not
critical because their management should be identical. Some
workers believe that these two tumors are variants of the same
entity.30
Oncocytoma (Oxyphilic Adenoma)
Oncocytomas are rare benign tumors that typically appear in
elderly patient as a hard nodule. They are most often found in
the parotid glands but can be found in all major salivary glands.
The tumor is composed of cells with abundant granular eosi-
nophilic cytoplasm and round, central, or eccentric nuclei with
distinct nucleoli. The cells are uniform and arranged in solid
acinar groups or parallel columns with sparse, delicate support-
ing stroma. Unlike most Warthin's tumors, oncocytomas lack
lymphoid infiltrates. A malignant variant has been described.33
Cytology
In aspirates from oncocytomas, the principal feature is solid
plugs and sheets of polygonal, monomorphous oncocytic cells
in a clean or slightly bloody background (Fig. 22.17). These cells
are identical to the oncocytes of Warthin's tumor. Lymphoid
cells and a proteinaceous precipitate are not observed in onco-
cytomas.
Key features of oncocytoma
Clusters of uniform large cells with abundant finely
granular cytoplasm (oncocytes);
Round nuclei usually centrally located within the cell
and containing distinct nucleoli; and
Absence of fluid, debris, and lymphoid cells.
Fig. 22.17 Oncocytoma. Sheets of polygonal oncocytic cells with large
granular cytoplasm (May-Grünwald-Giemsa x HP).
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