Histopathology of Parotid Pleomorphic Adenomas: A “Pleomorphic Approach” to a Demanding Lesion

Abstract

OBJECTIVES/HYPOTHESIS: The aim of this study was to identify potential associations between epidemiologic, morphologic, and histopathologic features in pleomorphic adenomas (PAs) of the parotid gland in order to extract information about the natural course and biologic behavior of these lesions on the basis of a single-center series of 845 cases within a period of 15 years. STUDY DESIGN: Retrospective study in a tertiary academic center. METHODS: For this study, an experienced head and neck pathologist critically re-evaluated the histological slides of the pathological specimens of all patients who underwent a parotidectomy for PA of the parotid gland between 2006 and 2020. RESULTS: A total of 845 cases made up our study sample. Our analysis showed a statistically significant association of the histologic subtype with younger age (P = .001) and maximal diameter (P = .044), with the hypocellular type being encountered more often in younger patients and in smaller lesions. The same subtype was significantly associated with an incomplete capsule (P = .001), pseudopodia (P = .006), and satellite nodules (P = .001). An incomplete capsule was associated with the presence of pseudopodia (P = .001) and satellite nodules (P = .001). CONCLUSION: It seems that various histologic subtypes have different capsule-producing properties. Apparently, over the course of time, tumor material builds a finger-like projection still inside the capsule, separates itself from the parenchyma with fibrous tissue still remaining enclosed within the capsule (pseudopodium), slowly penetrates the capsule (incomplete capsule), and leaves the main lesion taking a part of the capsule with it (satellite nodules). Laryngoscope, 132:73-77, 2022.