Pleomorphic adenoma with extensive lipometaplasia: report of three cases.

We report a series of three cases of pleomorphic adenoma with extensive lipometaplasia, a recently described subtype of pleomorphic adenoma of salivary gland origin. Two patients were female and one male, ranging in age from 30 to 45 years. Two occurred in the minor salivary glands of the lip and palate, respectively, and one in the parotid. Typical histologic findings are presented. In addition, one case consists of a proliferation of spindle cells with an interesting combination of mature adipose tissue, hyaline cartilage, and bone in the absence of ductal structures. The differential diagnosis, as it pertains to other fat-containing tumors (such as lipoadenoma, spindle cell lipoma, interstitial lipomatosis, and benign mesenchymoma), is discussed. It is likely that the ability of myoepithelial cells to undergo various metaplasias is the cause of the unusual histologic appearances of this tumor.