Assessment of immunomorphological patterns in metastatic and non-metastatic lymph nodes of oral squamous cell carcinoma patients

Introduction: Metastasis in oral epidermoid carcinoma oral squamous cell carcinoma (OSCC) can occur differently. Lymph nodes and lymphatics which drain the tumour site, serve as the most common pathway for metastasis. Lymph nodes serve as a marker of the immune status of the patient, which in response to a metastatic event, may facilitate or resist the homing of tumour cells. This host immune response is identified by examining various immunoreactive patterns in the lymph node. Materials and Methods: A total of 100 cases of OSCC underwent radical neck dissection and were assessed for grading of tumour histology, immunomorphological patterns (IMPs) in metastatic and non-metastatic lymph nodes as well as the pattern of tumour involvement in positive lymph nodes. All the lymph nodes were histologically evaluated and were grouped as metastatic and non-metastatic lymph nodes, showing four different patterns lymphocyte predominance (LP) pattern, germinal centre predominance (GCP) pattern, sinus histiocytosis (SH) pattern and lymphocyte depleted pattern. Metastatic positive nodes were further evaluated for the pattern of tumour cell invasion within the lymph node. Results: A total number of 1167 lymph nodes were histologically evaluated. Out of all, 239 lymph nodes were positive for metastasis and 928 were non-metastatic nodes. The most frequently encountered lymph node pattern was of LP (854 nodes), followed by GCP (157 nodes), SH (120 nodes) and lymphocyte depleted (36 nodes), respectively. Out of 1167, 239 nodes were positive for metastasis, indicating that as the stage advances, the GCP type predominates (the predominant IMP shifts from LP to GCP), so that facilitating or favouring metastasis. Moreover, the most common pattern seen in metastatic deposits observed was islands/sheets followed by strands/cords. Conclusion: IMPs of regional lymph nodes of OSCCs seem to be an essential factor in serving as a prognostic indicator. Whereas the cell-mediated immune response represented by LP and SH resist the metastasis process, the humoral reflected by GCP favours metastasis.