Cytomorphology of polymorphous low grade adenocarcinoma--diagnosis and pitfalls

Polymorphous Low Grade Adenocarcinoma (PLGA) arises characteristically in the minor salivary glands. Histological diagnosis of this tumour has improved following awareness and well characterized histologic features. However cytologic diagnosis is difficult. Ten cases of PLGA were identified on review of 61 cases of palatal salivary gland tumours aspirated over a 17 year period. Seven of these had been diagnosed as salivary gland tumours but had not been further characterized, while two cases had been diagnosed as adenoid cystic carcinoma initially. In only one case a differential diagnosis between pleomorphic adenoma and PLGA had been considered. Cytologic diagnosis of PLGA is difficult but possible if an attempt is made to identify specific cytologic criteria.