Myoepithelial carcinoma arising in a pleomorphic adenoma of the parotid gland: report of a case with cytopathologic findings.
BACKGROUND
Carcinoma arising in a mixed tumor, or carcinoma ex pleomorphic adenoma (CEPA), is an uncommon primary salivary gland neoplasm. Among the various types of carcinomas that can be seen histologically in a CEPA, myoepithelial carcinoma is one of the rarest forms.


METHODS
A 76-year-old woman presented with an incidental parotid/parapharyngeal mass. Computed tomography-guide fine needle aspiration (FNA) showed a biphasic neoplasm with epithelial and stromal components consistent with pleomorphic adenoma (PA). However, in addition, a distinct population of discohesive atypical and pleomorphic cells with high nuclear/cytoplasmic ratio was noted in the background. In the cytopathologic diagnosis a suspicion was raised about a possible CEPA. Subsequent resection of the parotid mass confirmed the presence of low grade myoepithelial carcinoma arising in a PA.


CONCLUSIONS
Although uncommon, CEPA should be suspected on FNA when atypical cytomorphologic characteristics are observed. In rare cases a myoepithelial carcinoma also arises in a preexisting PA, necessitating an accurate interpretation for more definitive therapy.
Parwani
Anil V
AV
Department of Pathology, The Johns Hopkins Hospital, Baltimore, Maryland 21287-6940, USA.
Lujan
Giovanni
G
Ali
Syed Z
SZ
D008949:Adenoma, Pleomorphic / Q000175:diagnosis* / Q000473:pathology; D000368:Aged; D044963:Biopsy, Fine-Needle; D002277:Carcinoma / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006801:Humans; D009208:Myoepithelioma / Q000175:diagnosis* / Q000473:pathology; D010307:Parotid Neoplasms / Q000175:diagnosis* / Q000473:pathology