Parotid gland tumours in the ENT Department in Międzyleski Hospital in Warsaw between 2007 and 2014

Parotid gland tumours comprise 3% of all head and neck tumours. Although uncommon they are a histologically diverse group of tumors. The WHO classification of salivary gland tumours from 2005 recognizes 24 different malignant subtypes. They present different clinical courses and varying prognoses. Nearly 80% of salivary gland tumours are located in the parotid gland.

Our study evaluated retrospectively 445 patients with parotid gland tumours treated in our hospital in the period between 2007 and 2014. We analyzed surgical treatment and histological diagnosis.

There were 253 (56.9%) women and 192 (43.1%) men. The incidence of benign neoplasms was 90%. The most frequent benign tumour was pleomorphic adenoma (46%) and Whartin's tumour (35%). The most commonly found malignant tumour was acinic cell carcinoma (23%) and adenocarcinoma (13%). Non-Hodgin lymphoma in the parotid gland constituted nearly 17% of all malignant lesions. Hybrid tumours were diagnosed in 5 cases. Each patient underwent surgical procedure. Temporary facial nerve paralysis after surgery was diagnosed among 10 patients. Additionally, among 4 patients permanent facial nerve paralysis was diagnosed, which appeared before surgery or during surgical resection of the infiltrated facial nerve.

In this study the frequency of benign neoplasms was higher and its histopathology was different than in the literature. The most common malignant parotid gland neoplasm was acinic cell carcinoma. The study presents 5 cases of hybrid neoplasms which are very uncommon and cause difficulties with prognostic evaluation and treatment selection.