Peri-Implant Oral Squamous Cell Carcinoma (OSCC): Clinicopathological Features and Staging Issues

Background: Eighty-five percent of peri-implant malignancies are oral squamous cell carcinomas (OSCCs), and most of them are misdiagnosed as peri-implantitis because of their clinical and radiological presentation; few studies have focused on addressing and solving the diagnostic issues related to peri-implant OSCCs. Objectives: The study aimed to describe the clinicopathological features of peri-implant OSCCs and to report the staging issues related to the diagnosis of these lesions. Methods: This retrospective cohort study included patients who received a diagnosis of and treatment for peri-implant OSCCs at the Unit of Dentistry of the "Aldo Moro" University of Bari (Italy) from 2018 to 2024. By using descriptive statistics, the authors highlighted the diagnostic issues related to the clinical presentation, radiological features, and histology of peri-implant OSCCs. Results: A total of 13 women and 8 men with a mean age of 70.6 ± 11.7 years met the inclusion criteria; the medical history of the participants showed potentially malignant disorders (OPMDs) in 52.4% of patients, whereas 14.3% had already developed an OSCC. The patients showed 24 peri-implant OSCCs; the clinical presentation was leuko-erythroplakia-like (41.7%) or erythroplakia-like (58.3%), thus simulating peri-implantitis; in addition, 52.0% of dental implants involved had a probing pocket depth ≥ 10 mm, further mimicking peri-implantitis. Panoramic radiograms and cone beam computed tomography were of little use in studying bundle bone-implant interfaces; in particular, the tomography showed circumferential bone resorption only in peri-implantitis-like OSCCs. In total, 91.6% of histological examinations of OSCCs showed peri-implantitis-like inflammation; early-stage lesions (pTNM I-II) accounted for 33.3%, whereas late-stage lesions (pTNM III-IV) accounted for 66.7%; lymph nodal metastases occurred in 25.0% and 62.5%, respectively. The mean follow-up was 3.4 ± 1.0 years; all patients with OPMDs had poorly differentiated tumors and thus showed a worse prognosis than those without OPMDs (mean disease-free survival of 15.5 ± 7.7 months and 44.7 ± 12.1 months, respectively). Conclusions: The results of the study showed that peri-implant OSCCs occurred most frequently in patients with OPMDs or previous OSCC; in addition, peri-implant OSCCs required demolition rather than conservative excision, and the prognosis of patients strictly depended on the grade of the cancer. In the authors' experience, the clinical-radiological presentation simulating peri-implantitis was the feature that concurred most in complicating the diagnosis of those tumors.