Probability and pattern of occult cervical lymph node metastases in primary parotid carcinoma

The present study was undertaken to evaluate real probability and pattern of cervical occult lymph node metastases (OLNM) in primary parotid carcinoma (PPC). We carried out a retrospective analysis of 66 patients treated in years 1992-2010 due to PPC, who underwent elective neck dissection (END). In search of risk factors for OLNM, we analysed the following parameters: age, sex, pT-Status, tumour size, skin invasion, facial nerve palsy, tumour fixation, extraparotid extension, localization, grade, histology, intra/periparotid LN metastases (IPLNM). OLNM was observed in 30.3% of patients. In a univariate analysis statistical significance was found for IPLNM, extraparotid extension and high risk histology. A multivariate analysis showed statistical significance only for the first variable. The most common location of cervical OLNM was level II (80%), then III (45%) and V (30%). In a compilation of our own material with data from the literature (5 series), we obtained a group of 80 patients with OLNM, selected out of 650 patients with cN0 (12.3%). The proportion of metastases to particular levels was the following: 69%-II, 22.5%-III, 20%-I,16%-V, 7.5%-IV. END should be carried out in case of all T3/T4a carcinomas with minimal range of levels II and III. Removal of levels Ib and Va is recommended as well. In the T1/T2 carcinomas with high grade/high risk histology, END should be performed including levels II and III.