Introduction Polymorphous low grade adenocarcinoma is a tumor of limited malignancy involving predominantly minor salivary glands, particularly of the palate, where it represents the second most frequent malignant tumor (3,7,8). There are occasional reports of involvement of major salivary glands, including the parotid gland (10,12,14,15,19). Its behavior is indolent, with a 10–15% rate of local recurrence, a regional lymph node metastasis rate of approximately 10%, and rare reports of distant spread (23,24). These tumors are charac- terized by architectural diversity and cytologic uniformity. The nuclei are oval to spindled with fine chromatin and in- conspicuous nucleoli. A moderate amount of eosinophilic cytoplasm is characteristic, and mitoses and necrosis are rare. Tubular, cribriform, papillary, solid, and fascicular are- as alternate within the tumor and an infiltrative margin with perineural invasion is often seen. A myxoid, hyaline, or myxohyaline stroma is always seen and often forms intratu- bular globules (20,21,26). The histologic differential dia- gnosis includes adenoid cystic carcinoma and pleomorphic and monomorphic adenomas. Experience with the cytology of this tumor is limited to occasional case reports (5,9). This tumor is increasingly being recognized histologically; and with the routine use of FNAC in the evaluation of head and neck lesions, this tumor is expandingly in the scope of the cytopathologist. This is of particular relevance when the tumor presents in an atypical fashion, either as a metastasis or rarely in a major salivary gland. This study was undertaken to assess the value of imprint cytology in the diagnosis of PLGA and highlight the pitfalls and dilemmas. Study design A case of PGLA arising in the right parotid gland region of a 65-year old woman with both imprint cytology and histologic confirmation, was retrieved from the surgical pathology and cytopathology files of the Papanicolaou Hos- pital of Salonica, and Regional Hospital of Alexandrou- polis. Cytologic material was obtained by touch imprint smear- ing. Air-dried smears were stained with the Hemacolor ra- 3 REVIEW ARTICLE POLYMORPHOUS LOW GRADE ADENOCARCINOMA OF THE PAROTID GLAND. CYTOLOGICAL, HISTOLOGICAL AND IMMUNOHISTOCHEMICAL FEATURES AND REVIEW OF THE LITERATURE Demetrio Tamiolakis 1 , Vasilios Thomaidis 2 , Ioannis Tsamis 2 , Eleni Kariki 3 , Athanasia Kotini 4 , Maria Lambropoulou 5 , Panagiotis Boglou 5 , Nikolaos Papadopoulos 5 General Hospital of Alexandroupolis, Greece: Department of Cytology 1 , Department of Maxillofacial Surgery 2 ; Papanicolaou Hospital of Salonica, Greece: Department of Pathology 3 ; Democritus University of Thrace, Greece: Department of Medical Physics 4 , Department of Histology – Embryology 5 Summary: Aim: Polymorphous low grade adenocarcinoma of the salivary glands (PLGA) is a low grade neoplasm that pre- dominantly occurs in the minor salivary glands. In this site is amenable to biopsy and histologic diagnosis. However, ex- perience 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 hyper- cellular 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, pleo- morphic 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. Key words: PLGA; Salivary gland tumors; Cytology; Histology; Immunohistochemistry ACTA MEDICA (Hradec Králové) 2004;47(1):3–6