Fine-needle aspiration findings in patients with polymorphous low grade adenocarcinoma of the salivary glands

BACKGROUND. Polymorphous low grade adenocarcinoma of the salivary glands (P LAC) is a low grade neoplasm that predominantly occurs in the minor salivar y glands. In this site it is amenable to biopsy and histologic diagnosis. H owever, experience with fine-needle aspiration (FNA) biopsy findings in the se tumors is limited. The authors describe the FNA cytology of this entity. METHODS. Fine-needle aspirates from two primary parotid and three metastati c PLACs were reviewed and correlated with their histology. RESULTS. All aspirates showed similar cytologic features, with hypercellula r smears showing branching papillae, sheets and clusters composed of bland uniform cells with round-to-oval nuclei, dispersed chromatin, and absent or inconspicuous nucleoli. The cells generally had a scant-to-moderate amount of eosinophilic cytoplasm. Mitoses and nuclear pleomorphism were absent. T hese cells formed tubular structures containing hyaline globules in all cas es and often a dispersed myxohyaline stroma. Bare nuclei also frequently ap peared in the background. Two cases, which had prior histologic diagnoses, were diagnosed on FNA as metastatic PLAC. One metastatic case was diagnosed as benign metastasizing pleomorphic adenoma. One primary case was diagnose d as adenoid cystic carcinoma and one case as PLAC on FNA. CONCLUSIONS. The cytologic differential diagnosis of PLAC includes adenoid cystic carcinoma, pleomorphic adenoma, and monomorphic adenoma. PLAC should be considered in the differential diagnosis of head and neck masses, where the cytology suggests one of these tumors, even when the clinical context (involvement of a major salivary gland, lymph node metastasis) is not typic al of PLAC. Cancer (Cancer Cytopathol) 1999;87:31-6. (C) 1999 American Canc er Society.