Intraoral Salivary Gland Malignancies: Targeted Surgical Therapy Is Guided by Pre-Operative Mini-Invasive Grading ^†

Malignant neoplasm of the salivary glands account for 3% to 6% of all head and neck cancers. The incidence of malignant salivary gland tumors is considerably higher in minor salivary glands (MSG) accounting for 30% of all salivary cancers [1] and can present themselves in a very elusive fashion because of the heterogeneity in subsite and wide spectrum of histological subtypes. The surgical therapy depends on site, stage, and histological grading [2].

The aim of this study is to highlight the importance of achieving a preoperative histological diagnosis focusing on histological subtype and grading in order to sketch out a targeted surgical therapy.

The authors selected all cases of MSG malignancies treated from 2000 to 2018 from the Complex Operating Unit of Odontostomatology of University of Bari. All the patients in the diagnostic phase underwent to clinical examination, high definition intraoral ultrasonography, TC/MRI, pre-operative FNAB/FNAC with cytological/histological and immunohistochemical examination. Surgical therapy was: conservative for low-grade malignancies (LGM), and resective with neck dissection for high-grade malignancies (HGM).

The authors selected 146 patients. In all cases the histological diagnosis and grading was achieved in the pre-operative phase. 94 were diagnosed as LGM and 52 as HGM. About the LGM:

• Twelve cases were diagnosed as Polymorphous Low Grade Adenocarcinoma (PLGA): 9 M and 3 F, mean age 54, 10 on palate and 2 on cheek;
• Forty-one cases were diagnosed as low-grade Mucoepidermoid Carcinoma: 29 F and 12 M, mean age 37, 33 on the palate, 4 on the cheek, 2 on the lip and 2 on the tongue;
• Thirty-four cases were diagnosed as low-grade Adenoidocistic Carcinoma: 18 F and 16 M, mean age 61, 29 on the palate, 1 on the cheek, 3 on the lip and 1 on the tongue;
• Seven cases were diagnosed as Intercalated Duct Carcinoma: 3 F and 4 M, mean age 64, localized on the palate.

About the HGM:

• Nine cases were diagnosed as Clear cell Carcinoma: 4 F and 5 M, mean age 63, 8 on the palate and 1 on the lip;
• Nineteen cases were diagnosed as High-grade Mucoepidermoid Carcinoma (of which 5 clear cell high grade mucoepidermoid carcinoma, 6 on long-standing Pleomorphic Adenoma): 14 F and 5 M, mean age 41, 16 on the palate, 1 on the cheek, 1 on the lip and 1 on the tongue;
• Thirteen cases were diagnosed as high-grade Adenoidocistic Carcinoma (of which 3 clear cell high grade mucoepidermoid carcinoma, 2 on long-standing Pleomorphic Adenoma): 5 F and 8 M, mean age 54, 10 on the palate, 2 on the cheek and 1 on the lip;
• Eleven cases were diagnosed as basaloid or undifferentiated carcinoma: 5 F and 6 M, mean age 62, 9 on the palate and 2 on the cheek.

In conclusion, preoperative FNAB/FNAC for histological diagnosis of MSG malignancies is mandatory in order to make decisions on the type of surgical treatment.