Maxillary Sinus Pleomorphic Adenoma: A Systematic Review

Background: Pleomorphic adenoma (PA), also known as a mixed tumor, is a neoplasm of the glandular tissue. The maxillary sinus (MS) is an atypical location of PA; however, as an empty cavity inside the bone, it predisposes tumors to develop unnoticed. The aim of the following systematic review was to identify and characterize the diagnostics and prognosis of maxillary sinus pleomorphic adenoma (MSPA). Methods: The cases of MSPA that underwent treatment and were observed for possible recurrence were qualified for the review. The medical databases were searched using the following engines: ACM, BASE, Google Scholar and PubMed. The risk of bias was assessed using the JBI Critical Appraisal Tool for Case Reports. The extracted data were tabulated and summarized in a descriptive manner. Results: To the best knowledge of the authors, only seven cases of MSPA were described in the last 20 years. Relapse occurred in three of these cases and malignant transformation occurred in two. The longest recorded time without recurrence was 4 years. The size of the detected MSPA in the largest dimension ranged in various cases from 40 to 60 mm, with an average of 48 mm. Discussion: All but one of the seven included reports showed flaws during the risk of bias assessment. Only in two of seven reported cases was there no reason to suspect that the tumor had penetrated the sinus from the oral or nasal cavity. The MS is disadvantageous as a location as tumors occupying the entire volume of the sinus are often diagnosed. Recurrences and malignant transformations seem to be frequent and often remain undetected for a prolonged period. Other information: This research received no external funding. OSF Registries number: 8KVGM.