PART TWO
Diagnostic Cytology
Fig. 22.1 FNAB slides. Smears from a salivary gland tumor stained with
May-Grunwald-Giemsa, Papanicolaou, MIB-1 and immunocytochemistry.
Fig. 22.2 Normal salivary gland. Tissue section (H&E x MP).
through Stensen's duct into the oral cavity. The submandibular
glands are of endodermal derivation and secrete a mixed but
predominantly serous substance. They drain via Wharton's duct
at the sublingual caruncle close to the frenulum of the tongue.
The sublingual glands lie in the floor of the mouth adjacent to
the midline and produce a mixed, primarily mucous secretion.
Minor salivary glands are nonencapsulated aggregates of
mucous or mixed mucous-serous glands located superficially
over the lips, throughout the oral cavity, nasopharynx, sinuses,
trachea, and bronchi.
The glands are organized into lobules. Each lobule consists
of a cluster of acini around a terminal duct system. The acini
are made up of pyramid-shaped epithelial cells that have eccen-
tric round nuclei (Fig. 22.2). The cytoplasm is abundant, finely
granular, and acidophilic in serous glands and clear in mucus-
secreting glands. Flat myoepithelial cells with elongated nuclei
form an outer layer around each acinus. From the lobules, the
secretion is conveyed via interlobular ducts to the main secretory
ducts. The smallest excretory ducts are lined by cuboidal cells,
whereas those lining larger ducts are tall and columnar. Near the
orifice in the oral cavity, the ducts are lined by stratified squamous
epithelium. A layer of myoepithelial cells is present between the
lining epithelial cells and the basement membrane.
With increasing age, the cells of acini and ducts occasionally
transform into oncocytes.16 An oncocytic cell is a large epithe-
lial cell with distinct cell borders, eosinophilic finely granular
cytoplasm, and a round nucleus, often with a central prominent
nucleolus.
The parotid glands normally contain small lymphoid aggre-
gates and one or more nodes. Salivary ducts and acini have
also been found in lymph nodes outside the capsule of parotid
glands.17
Cytology
Aspiration of normal or near-normal salivary glands usually
yields only a small amount of epithelial cells. Normal structures
are often seen as "contamination" in aspirates from pathologic
lesions. The normal structures are viewed as basically acinar
cells in well-preserved cohesive ball-like formations (Fig. 22.3)
and as ductal cells in monolayered sheets or small tubuli.
The acinar cells have a central or eccentric, small rounded
nucleus with a small nucleolus. The cytoplasm is abundant,
granular, and rather foamy (Fig. 22.3). Bare cell nuclei are
usually observed in the background. Terminal secretory ducts
appear as short tubular structures, and larger ducts appear as
flat clusters or sheets of cuboidal or columnar cells with evenly
spaced monomorphous nuclei (Fig. 22.3). Myoepithelial cells
are only occasionally noted as small dark nuclei superimposed
in the clusters.
non-neoplastic Lesions
Cysts
Benign and malignant salivary gland lesions may have a cystic
component. Cystic aspirates therefore cause a special problem
because the cyst fluid alone does not allow a morphologic evalu-
ation. The most common cyst is a ductal retention cyst due to
obstruction (sialolithiasis), and it contains watery fluid or, in
cases of inflamed cysts, a cloudy fluid.
Retention cysts of the major salivary glands that are deep
seated are at palpation felt to be rather firm. They are therefore
likely to be diagnosed clinically as solid neoplasms; however,
FNA readily discloses the nature of the lesion. In such cases, a
clinical follow-up after a few weeks should suffice. If the cyst
recurs, it should be reaspirated to attempt a cure and to obtain a
further sample for cytologic evaluation.
If a residual mass persists, however, the aspiration should
be repeated because some benign and malignant salivary gland
tumors may have both a solid and a cystic component. An initial
sampling from a cystic portion of the tumor may therefore be
misleading, and a repeat biopsy should be performed from the
walls of the cyst to help establish a diagnosis.
Branchial cleft cysts can occasionally appear in the anterior
portion of a parotid gland and on clinical examination may be
mistaken for a salivary gland lesion.
Small superficial cysts are often encountered in minor sali-
vary glands of the lips and the oral mucosa. They are in general
accurately diagnosed clinically. At aspiration, such cysts yield a
clear mucous fluid and leave no residual mass.
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