[Polymorphous low-grade adenocarcinoma: a palatine and a labial location]

Polymorphous low-grade adenocarcinoma (PLGA) is a variant of malignant tumor of minor salivary glands. We had for aim to discuss morphology, evolution and differential diagnosis of this rare tumor.

The first case was a 65-year-old woman admitted for a two-month history of a right submaxillary swelling. The examination revealed a tumor of the right side of the palate. Biopsy was positive for a pleomorphic adenoma. The mass was enlarged and surgical resection was performed. The diagnosis was a partially resected PLGA. The patient also received adjuvant radiotherapy. There was a local recurrence 28 months after complete treatment. The second case was a 57-year-old woman who consulted for a 12-year history of lower lip swelling. The examination revealed a painless 2cm long located nodule in the mucosal side of the lower lip. An excisional biopsy was performed. The pathological examination concluded to a completely resected PLGA. The patient was free of disease at 54 months follow-up.

The morphologic diversity and cytological uniformity of PLGA may make the differential diagnostic difficult especially with adenoid cystic carcinoma and pleomorphic adenoma. Its aggressiveness is proved by a local infiltrative growth pattern requiring a large surgical excision.