Korean J Pathol.
1999 Jul;33(7):517-520.
Malignant Myoepithelioma Arising in a Recurrent Pleomorphic Adenoma: A case report
- Affiliations
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- 1Department of Pathology, Chosun University College of Medicine.
- 2Department of Diagnostic Pathology, Samsung Medical Center, Sungkyunkwan University College of Medicine, Seoul 135-710, Korea.
Abstract
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Malignant myoepithelioma is a rare neoplasm of salivary gland which may either
arise de novo or develop in a pre-existing pleomorphic adenoma. The malignant
myoepithelioma occurs in 0.45% of major salivary gland tumors. Malignant
myoepitheliomas arising in the pleomorphic adenoma number less than 20 in English
literature and 1 in Korea. We describe a case of malignant myoepithelioma arising in a
recurrent pleomorphic adenoma of the left parotid gland of a 61-year-old man. The
tumor was ill-defined and composed of polygonal or plasmacytoid myoepithelial cells.
Infiltration to surrounding tissue, hemorrhage, necrosis, increased mitotic activity and
vascular tumor emboli indicated its malignant nature. There were several satellite
nodules with histologic features of typical pleomorphic adenoma. Immunohistochemically,
tumor cells were reactive for S-100 protein, AE1/AE3, vimentin, smooth muscle actin
and glial fibrillary acid protein.