Recurrent Pleomorphic Adenoma of the Parotid Gland: Experience of 128 Patients with First Recurrence

Abstract

Objective. Recurrence is common after inappropriate surgical procedures for parotid pleomorphic adenoma (PA). However, there are some controversies regarding intraoperative tumor rupture and disease recurrence; therefore, our goal was to clarify this relationship by describing our experience with 128 cases of recurrent parotid PA. Methods. Patients suffering from a first recurrence of parotid PA were prospectively enrolled, and data regarding the operation, pathology, immunohistochemistry, and recurrence pattern (outside the previous surgical field vs. inside the previous surgical field) were extracted and analyzed. The recurrent lesions were divided into two groups based on the location of nodularity. Results. Thirty-five patients had recurrent disease outside the previous surgical field; there were 105 nodules with a mean size of 1.0 (range: 0.4–3.0) cm and 983 nodules with a mean size of 1.55 (range: 0.5–4.5) cm within the field, and the difference was significant ( $p=0.001$ ). The mean values of Ki-67 in nodules outside of and within the previous surgical field were 4.7% (range: 2%–10%) and 2.1% (range: 1%–7%), respectively, and the difference was significant ( $p<0.001$ ). In nodules outside the previous surgical field, cell-rich nodules were noted in 71.6% of cases; in nodules within the previous surgical field, cell-rich nodules were found in 30.4% of cases, and the difference was significant ( $p<0.001$ ). Conclusion. Tumor rupture is not the only cause of disease recurrence, and recurrent PAs outside the previous surgical field are smaller in size, have higher Ki-67 expression, and have more cell-rich nodules than those within the surgical scar.