Anatomic Pathology: Salivary Gland Pathology

297) A 29-year-old woman underwent resection of an intranasal mass. Histologic examination of the lesion resulted in a diagnosis of pleomorphic adenoma. Foci of squamous metaplasia were evident in the tumor, as shown in the photograph. Which one of the following lesions is LEAST likely to display squamous metaplasia?

• Different types of metaplasia (e.g., squamous and sebaceous) sometimes occur in various salivary gland tumors.

• Pleomorphic adenoma sometimes displays squamous metaplasia, as in this case.

• Basal cell adenoma and basal cell adenocarcinoma can show squamous (as well as sebaceous) elements.

• Squamous and sebaceous differentiation have been described in epithelial-myoepithelial carcinoma.

• Squamous differentiation does not usually occur in adenoid cystic carcinoma. This generality is sometimes useful in terms of differentiating adenoid cystic carcinoma from various mimics.

Chiosea SI, Peel R, Barnes EL, Seethala RR: Salivary type tumors seen in consultation. Virchows Arch 2009;454:457-466.

Eveson JW, Kusafuka K, Stenman G, Nagao T: Pleomorphic adenoma.In Barnes L, Eveson JW, Reichart P, Sidransky D (eds): Pathology and Genetics of Head and Neck Tumours. World Health Organization Classification of Tumours.Lyon: IARC Press, 2005, pp 254-258.

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