Analysis of the patterns of cervical lymph node metastases in oropharyngeal carcinomas in relation to the extension of the primary tumour

To assess the incidence and patterns of cervical lymph node involvement according to the location and the relation of the primary tumour to the parapharyngeal fasciae, compartments and tissues arising from different branchial arches. Patients and Methods: The findings of clinical and CT examinations of 143 patients with histological evidence of oropharyngeal carcinoma were evaluated retrospectively. Local tumour spread, relation of the primary to the parapharyngeal fasciae, compartments and to the borders of tissues arising from different branchial arches were analysed and related to cervical lymph node involvement. Results: Lymph drainage of the oropharynx and neighbouring neck regions is determinated by the embryological development of the branchial arches and somites. Oropharyngeal carcinomas are tumours arising from tissues of the 2 nd and 3 rd branchial arches. The lymph of these tissues is collected by the vessels of the jugular neck node chains. If tumour invades tissues arising from the 1 st branchial arch (structures of the oral cavity and floor of the mouth) tumour spreads into the ipsilateral lymphatic vessels arising from the 1 st branchial arch and the submaxillary lymph nodes. If tumour invades tissues arising from occipital and cervical somites (posterior wall of the nasopharynx, retropharyngeal compartment and recessus submuscularis) metastases in the retropharyngeal and spinal-accessorial lymph nodes may appear. Regarding the tumour invasion of the subdistricts of the oropharynx totally different tumours were found. Tumour invasion of neighbouring structures was documented for the nasopharynx in 15%, for oral cavity and the floor of the mouth in 34%, the larynx in 24% and the hypopharynx in 22% of the cases, From these different patterns of local tumour spread different patterns of lymph node involvement resulted. Nodal involvement was found in 71%. In all these cases metastases in the ipsilateral upper jugular lymph nodes were present. The frequency of metastases in the jugular lymph node chains decreased in cranio-caudad direction (upper jugular group 100%, middle 18%, lower jugular group 5%). The frequency of bilateral jugular lymph node involvement (25%) increased in the some measure as the tumour approached the midline or crossed it. Conclusions: Knowledge of regular patterns of spread of oropharyngeal carcinoma is important for treatment procedures, especially for 3-dimensional radiotherapy.