Histopathological Findings of Intraoral Pleomorphic Adenomas: A Retrospective Study of a Case Series.

The aim of this study was to describe the clinicopathological features of 21 cases of intraoral pleomorphic adenoma (PA), with emphasis on histopathological findings. Between 2000 and 2016, all patients diagnosed as intraoral PA were retrieved and histopathological slides stained with hematoxylin and eosin reviewed to confirm the diagnosis. All tumors were classified histologically according to Seifert et al (1980). The clinical and histopathological variables were analyzed using the Fisher's exact test, considering a significance level of 5% (P < .05). Plasmacytoid (85.7%), spindle (38.1%), and epithelioid (9.5%) myoepithelial cells were observed. Oncocytic (47.6%) and mucous (19%) cells were also found. The stroma was predominantly fibrous (95.2%), followed by myxoid (66.7%), hyaline (61.9%), and chondromyxoid (33.3%). Squamous (57.1%), adipose (47.6%), sebaceous (14.3%), and bone (14.3%) differentiations were found. Additionally, a group of tumors presented pleomorphism (23.8%), mitoses (14.3%), capsule infiltration (9.5%), and necrosis. The presence of cystic structures occurred significantly in patients older than 30 years (P = .04) and mitoses were more observed in PA from buccal mucosa (P = .026). All cases that presented plasmacytoid cells were smaller than 1.5 cm (P = .015). All tumors with up to 50% stroma area presented with size smaller than 2.0 cm (P = .013). Intraoral PA presents a large morphological spectrum and several microscopic features are associated with clinical findings.