Clinicopathological study of involvement of the submandibular gland in oral squamous cell carcinoma

Our purpose was to provide a pathological basis for preservation of the submandibular glands during neck dissection for oral squamous cell carcinoma (SCC) by investigating whether intraglandular lymph nodes exist in submandibular glands, and the modes of involvement of submandibular glands in oral SCC. We studied the records of 95 patients with oral SCC (other than that in the floor of the mouth) treated at our hospital from January 2017 to June 2018. The specimens of submandibular glands discarded after neck dissection were analysed, and serially sectioned. Sections 5μm thick were obtained at 0.5mm intervals and stained with haematoxylin and eosin for examination under light microscopy. A total of 116 specimens were obtained from the 95 patients, and about 5000 slides were evaluated. No intraglandular lymph nodes were detected in the submandibular glands. In the subgroup of patients whose primary tumours had extended into the floor of the mouth, four submandibular glands were involved by direct spread of the primary tumour. In the subgroup with metastases to level Ib lymph nodes, four submandibular glands were involved by extranodal extension from the metastatic nodes. No intraglandular lymph nodes or micrometastases were detected. We conclude that no intraglandular lymph nodes are present in submandibular glands, which may be involved by direct extension of the primary carcinoma or metastatic cervical lymph nodes with extranodal extension. Preservation of the submandibular glands during neck dissection seems to be feasible and safe in selected patients with oral SCC.