title: Pleomorphic adenoma with squamous and appendageal metaplasia mimicking mucoepidermoid carcinoma on cytology.
abstract: BACKGROUND
  Histological diversity is the hallmark of pleomorphic adenoma, the most common salivary gland tumor. It may cause difficulty in cytological interpretation, due to limited and selective sampling.
  
  
  METHODS
  A 16-year-old female patient presented with right cheek swelling. Fine needle aspiration cytology showed squamous cells, basaloid cells, and foamy cells, along with extracellular keratin and foreign body giant cells. Characteristic metachromatic fibrillary chondromyxoid stroma, which is usually seen in pleomorphic adenoma, was not seen in the aspirate. A diagnosis of mucoepidermoid carcinoma was given on cytology. Subsequent resection revealed an encapsulated pleomorphic adenoma, with extensive squamous metaplasia and appendageal differentiation on histology.
  
  
  CONCLUSIONS
  This case illustrates that pleomorphic adenoma with squamous metaplasia presents a potential for misinterpretation as mucoepidermoid carcinoma on cytology. We discuss the various pitfalls and the features that are helpful in distinguishing these two lesions.
authors.affiliation: Department of Pathology, Dr. Ram Manohar Lohia Hospital, New Delhi, India. meenakshibatrani@yahoo.co.in
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Batrani
authors.forename: Manju
authors.initials: M
authors.lastname: Kaushal
authors.forename: A K
authors.initials: AK
authors.lastname: Sen
authors.forename: Rajbala
authors.initials: R
authors.lastname: Yadav
authors.forename: N K
authors.initials: NK
authors.lastname: Chaturvedi