Question
A patient presented with a painless slowly growing swelling ,below and in front of the ear.Histopathological examination of the swelling showed the following features.What can be the most probable diagnosis?
A. Mucoepidermoid Carcinoma
B. Pleomorphic Adenoma
C. Adenoid Cystic Carcinoma
D. Warthin’s Tumor
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Correct Answer » B Explanation |
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Ans:B. Pleomorphic Adenoma.
Image shows:Pleomorphic adenoma. The epithelial element is comprised of ducts, acini, tubules, sheets and strands of cuboidal and myoepithelial cells. These are seen randomly admixed with mesenchymal elements composed of pseudocartilage which is the matrix of myxoid, chondroid and mucoid material.
Pleomorphic Adenoma (Mixed Salivary Tumour)
- This is the most common tumour of major (60-75%) and minor (50%) salivary glands.
- The tumour is commoner in women and is seen more frequently in 3rd to 5th decades of life.
- The tumour is solitary, smooth-surfaced but sometimes nodular, painless and slow-growing. It is often located below and in front of the ear .
MORPHOLOGIC FEATURES.
- Grossly, pleomorphic adenoma is a circumscribed, pseudoencapsulated, rounded, at times multilobulated, firm mass, 2-5 cm in diameter, with bosselated surface.
- The cut surface is grey white and bluish, variegated, semitranslucent, usually solid but occasionally may show small cystic spaces.
- The consistency is soft and mucoid.
- Microscopically, the pleomorphic adenoma is characterised by pleomorphic or ‘mixed’ appearance in which there are epithelial elements present in a matrix of mucoid, myxoid and chondroid tissue :
- Epithelial component may form various patterns like ducts, acini, tubules, sheets and strands of cells of ductal or myoepithelial origin.
- The ductal cells are cuboidal or columnar, while the underlying myoepithelial cells may be polygonal or spindle-shaped resembling smooth muscle cells.
- The material found in the lumina of ductlike structures is PAS-positive epithelial mucin.
Focal areas of squamous metaplasia and keratinisation may be present.
- Immunohistochemically, the tumour cells are immunoreactive for epithelial (cytokeratin, EMA, CEA) as well as myoepithelial (actin, vimentin and S-100) antibodies.
- Mesenchymal elements are present as loose connective tissue, and as myxoid, mucoid and chondroid matrix, which simulates cartilage (pseudocartilage) but is actually connective tissue mucin.
- The matrix of the tumour has been characterised as a product of myoepithelial cells as seen by S-100 immunostain positivity.