2000 Volume 47 Issue 4 Pages 307-323
Pleomorphic adenoma is the best-recognized tumor among those of salivary gland origin that also has the highest incidence. However, it is not uncommon for it to become malignant, and it has been noted that the frequency of malignancy increases as a result of the tumor persisting without being treated following the onset of adenoma. Carcinomatous components demonstrate various histological appearances, and in particular, there have been sporadic reports of carcinosarcoma in which malignant findings are not only observed in epithelial components, but in mesenchymal components as well. We conducted a histopathological study on cases of malignanttransformed pleomorphic adenoma, namely so-called malignant mixed tumor observed in our department. The subject cases consisted of a total of 19 cases registered in the diagnostic files of our department and included 12 males and 7 females. Age ranged from 46 to 87 (average 67.7) years old. The sites of occurrence consisted of the parotid gland in 17 cases, and palatal and buccal minor salivary glands in one case each. Histological types consisted of 7 cases of adenocarcinoma not otherwise specified, 3 cases of squamous cell carcinoma, 3 cases of salivary duct carcinoma, and one case each of polymorphous low-grade adenocarcinoma and epithelial-myoepithelial carcinoma, while the remaining were 2 cases of sarcomatoid carcinoma and 2 carcinosarcoma. We described herein their histological characteristics, discussed diagnostic problems in various instants in which each phenotype on this setting, and reviewed the literature, especially as to carcinosarcoma in contrast with those derived from other organs.