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Pleomorphic Adenoma Benign Mixed Tumor
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the most common salivary neoplasm
parotid tumors>minor gland tumors Although the basic tumor pattern is highly variable, rarely are the individual cells actually pleomorphic
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derived from a mixture of ductal and myoepithelial elements
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Clinical and Radiographic Features
a painless, slowly growing, firm mass at any age but is most slight female predilection.
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The palate is the most common site for minor gland mixed tumors
(60% of intraoral examples) >upper lip (20%) > buccal mucosa (10%). Palatal tumors almost always are found on the posterior lateral aspect of the palate smooth-surfaced, dome-shaped masses Palatal tumors are not movable
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Histopathologic Features
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typically a well-circumscribed, encapsulated tumor
A well-defined tumor has a thin fibrous capsule lack of complete encapsulation is more common for minor gland tumors
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The tumor is composed of a mixture of ductal epithelium and myoepithelial cells within a mesenchyme-like background that is highly variable ducts cystic structures islands or sheets of cells Cords of ductal epithelium Keratinizing squamous cells mucus-producing cells epithelium often forms
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Myoepithelial cells with a variable morphology
The highly characteristic "stromal" changes angular Spindled plasmacytoid ( resembling plasma cells ) (more prominent in tumors arising in the minor glands) cells are rounded and demonstrate an eccentric nucleus and eosinophilic hyalinized cytoplasm
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Stromal changes Myxomatous background chondroid appearance
hyalinized change Fat or osteoid (rarely)
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Myxomatous background
Extensive accumulation of mucoid material between the tumor cells
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chondroid appearance or chondroid metaplasia
(Vacuolar degeneration of cells in these areas)
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Cartilage may sometimes be present in the stroma.
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Many of the ducts and myoepithelial cells are surrounded by a hyalinized, eosinophilic background alteration
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A "classic" appearance with ductal elements in a myxoid stroma
The tubules is composed of two layers of cells
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Cords of ductal epithelium in a loose myxomatous stroma.
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