Postsurgical high grade transformation of polymorphous low grade adenocarcinoma of the retromolar trigone into adenocarcinoma not otherwise specified

Abstract

Malignant salivary gland tumors have been known to undergo transformation into more aggressive neoplasms with poorer prognosis in long standing or recurrent cases. This may be the result of the cell of origin to differentiate to the level of the original tumor or dedifferentiation of previously existing tumor cells. Dedifferentiation of Polymorphous low grade adenocarcinomas (PLGA) or transformation into a high grade component in recurring lesions has been reported. On transformation into high grade malignancy, salivary gland tumors do not show a total loss of original line of differentiation, especially when high grade adenocarcinomas arise from pre-existing carcinomas. Thus the term “High grade transformation” is preferred to “dedifferentiation” in these neoplasms. We present a case of PLGA of the right alveolar ridge in a 50 year old male, showing high grade transformation into Adenocarcinoma not otherwise specified (ANOS), after a period of five years of complete surgical removal.