Polymorphous Low Grade Adenocarcinoma of the Parotid Gland. Cytological, Histological and Immunohistochemical Features and Review of the Literature

Aim: Polymorphous low grade adenocarcinoma of the salivary glands (PLGA) is a low grade neoplasm that predominantly occurs in the minor salivary glands. In this site is amenable to biopsy and histologic diagnosis. However, experience with cytological findings in these tumors is limited. We describe the cytology of this entity. Experimental design: Touch imprint cytology of a primary parotid PLGA is specified and correlated with histology. Results: Smears were hypercellular showing branching papillae, sheets and clusters of uniform cells with bland nuclei, dispersed chromatin and no nucleoli. The cells had a scant to moderate amount of eosinophilic cytoplasm. They formed tubular structures containing hyaline globules. Conclusions. The cytologic differential diagnosis of PLGA includes adenoid cystic carcinoma, pleomorphic adenoma, and monomorphic adenoma. PLGA should be considered in the differential diagnosis of head and neck tumors, where the cytology suggests on of the above mentioned tumors, even when the clinical findings (involvement of a major salivary gland, lymph node metastasis) is not typical of PLGA.