ABSTRACT
Mucoepidermoid carcinomas (MECs) are a form of salivary gland malignancy. They are classified according to histological grade and perineural invasion (PNI). In another cancer subtypes, positive-PNI suggests increased poor prognosis; however, the role of isolated positive-PNI salivary gland MEC can still be better investigated as a risk factor. This study investigated whether isolated PNI is independently associated with poor outcomes. Retrospective study, cohort case-series, single-center hospital from 2009 to 2019. Patient demographics, primary tumor, intervention, and survival data are included. Univariate, multivariate, and Kaplan-Meier survival curve analyses were used for comparison.The study group consisted of 32 patients (15 PNI-positive tumors, and 17 PNI-negative tumors), all admitted for surgery. Univariate analysis showed differences in grade (p = 0.038), positive margins (p = 0.034), soft tissue invasion (p < 0.001), pathological stage (p = 0.014), recurrence (p = 0.015), distant metastasis (p = 0.015) and MEC related death (p = 0.015). The risk in PNI-positive patients to develop soft tissue invasion and positive surgical margins was OR = 8.57 and OR = 4.88, respectively. Multivariate analysis found age differences (p = 0.038), with OR = 1.08. The Disease Specific Survival (DSS) was worst in the PNI-positive group (log-rank p-value = 0.0011), where the probability of dying occurred in the 12-24 months period (log-rank p-value = 0.002). PNI-positive salivary gland MEC is an independent prognostic factor, with poor DSS, increased locoregional recurrence, close correlation with a more aggressive pattern of the disease, and should be reviewed as a high grade histological criteria. Our findings may imply changes in the clinical approach with a more aggressive attitude in the overall treatment.
ABSTRACT
PURPOSE The parotidectomy technique still has an elevated paresis and paralysis index, lowering patient life's quality. The correct identification of the facial nerve can prevent nerve damage. Fluorescent dye identifies nerves in experimental studies but only few articles focused its use on facial nerve study in parotidectomies. We aimed to stain the rat facial nerve with fluorescent dye to facilitate visualization and dissection in order to prevent injuries. METHODS Forty adult male Wistar rats were submitted to facial injection of saline solution (Gsf-control group, 10) or fluorescent dye solution (Gdye group, 30) followed by parotidectomy preserving the facial nerve, measuring the time for localization and facility of localization (LocTime and LFN). Nerve function was assessed using the Vibrissae Movements (PMV) and Eyelid Closure Motion (PFP) scores. RESULTS Nerve localization was faster in Gdye group, with 83% Easy LFN rate. The Gdye group presented with low nerve injury degree and better PMV and PFP scores, with high sensitivity and accuracy. CONCLUSIONS This experimental method of facial nerve fluorescence was effective for intraoperative nerve visualization, identification and preservation. The technique may be used in future facial nerve studies, translated to humans, contributing to the optimization of parotid surgery in the near future.
