Publication:

Identification of tertiary lymphoid structures in oral squamous cell carcinoma and its clinico-pathological associations

Background Tertiary lymphoid structures (TLS) are ectopic, vascularised lymphoid structures that may be found in and around tumor tissue. The role of TLS has been studied in few solid tumors in which high TLS expression was found to be favourable prognostic biomarker.

Methods The present study was a retrospective and prospective study for a period of one year. Resected specimen of Oral squamous cell carcinoma (OSCC) with no history of previous treatment were included. The presence of TLS was assessed in tumor proper, invasive front as well as in adjoining areas of tumor. The association of TLS with size of the tumor, degree of differentiation of the tumor, pattern of invasion/tumor budding, tumor infiltrating lymphocytes (TIL) and lymph node pattern have been studied.

Results 52 resected specimens of OSCC were evaluated in present study, out of which 24 (46.15%) showed presence of TLS. Amongst the tumor with TLS, 54.16% had size <2 cm, 62.5% were well differentiated carcinoma and 8.3% had worst pattern of invasion. TILs were distributed equally amongst three sites-  tumor proper, invasive front and the adjacent tissue, in the TLS positive cases. The lymphocyte predominant pattern of lymph node showed a strong association with the expression of TLS (37.5%).

Conclusions In the present study, TLS has been found to be associated with positive prognostic factors. Also, it has been found that TLS is not a proxy of the TILs. Identification and evaluation of TLS has a great potential as prognostic marker and needs evaluation.