Classic polymorphous adenocarcinoma: Fine needle aspiration cytopathology of eight cases

• Published in: Cytopathology (Oxford) 2021-11, Vol.32 (6), p.789-794
• Main Authors: Wakely, Paul E, Lott‐Limbach, Abberly A.
• Format: Article
• Language: English
• Subjects: Adenocarcinoma; Adenocarcinoma - diagnosis; Adenocarcinoma - pathology; Adenoid; Adenoma, Pleomorphic - diagnosis; Adenoma, Pleomorphic - pathology; Adult; Aged; Biopsy; Biopsy, Fine-Needle; Cancer; Carcinoma, Adenoid Cystic - diagnosis; Carcinoma, Adenoid Cystic - pathology; Cleft lip/palate; Cytopathology; Diagnosis, Differential; Female; fine needle aspiration; Humans; Male; Metastases; Metastasis; Middle Aged; Neoplasm Recurrence, Local; polymorphous adenocarcinoma; Salivary gland; Salivary Gland Neoplasms - diagnosis; Salivary Gland Neoplasms - pathology; Salivary Glands - pathology; Stroma
• ISSN: 0956-5507; 1365-2303
• DOI: 10.1111/cyt.13046

Introduction The cytopathology and diagnostic accuracy of salivary gland (SG) polymorphous adenocarcinoma (PAC) is the subject of a limited number of reports. We undertook a review of our experience with fine needle aspiration (FNA) biopsy and PAC. Materials and methods A search was made of our cytopathology files for PAC cases that also had histopathological confirmation. FNA biopsy smears and cell‐blocks were performed and examined using standard techniques. Results Eight FNA biopsy cases of histologically proven PAC from 7 patients [F:M = 1.3:1, age 39‐75 years, mean = 58] met study inclusion. Metastatic aspirates were most common (4), followed by 3 primary cases and 1 locally recurrent neoplasm. Primary FNA sites included hard palate (1 case), lip (1), and lateral tongue (1); all metastatic sites were in the neck. A precise cytologic diagnosis was made in 38% of cases; however, when applying the Milan classification system, 100% could be categorised as either malignant or of uncertain malignant potential. Ancillary immunohistochemical testing performed in 44% of the cases was non‐specific. Cytologic smears showed cellular uniformity and structural variety of cell groups with tubular, branching, cribriform, and convex patterns as well as variable, but occasionally abundant globular myxoid stroma leading to confusion with adenoid cystic carcinoma. Conclusion The imitative cytopathology of PAC with other SG neoplasms as well as its infrequency in routine FNA biopsy practice makes specific interpretation difficult, but using a classification system allows for appropriate patient management. Molecular testing in future specimens holds promise for enhancing diagnostic accuracy. The imitative cytopathology of polymorphous adenocarcinoma with other salivary gland neoplasms as well as its infrequency in routine fine needle aspiration biopsy practice makes specific interpretation difficult. Using a classification system with broad generic diagnostic groupings and malignancy risk such as the Milan system allowed 100% of our cases to be subdivided into categories permitting concrete medical decision making.