Peritumoural and Intratumoural Distribution of Langerhan Cell in Oral Squamous Cell Carcinoma and its Association with Known Prognostic Factors

Introduction: Oral Squamous Cell Carcinoma (OSCC) accounts for about 2/3rd of the Head and Neck Squamous Cell Carcinomas (HNSCC). It is the sixth most common cancer worldwide and the third most common cancer in developing countries including India. More than half the HNSCC patients have advanced disease at the time of diagnosis and overall long-term survival is low (50%), despite aggressive therapeutic regimens. This has demanded the need for prognostic indicators that can be used to improve the ability to select a more individualised approach for treatment relative to the risks of recurrence, metastases and death.

Aim: To study the intratumoural and peritumoural distribution and density of Langerhans Cells (LC) in OSCC using Immunohistochemistry (IHC) markers Cluster of Differentiation-1a (CD1a) and Langerin and to study its association with known prognostic factors.

Materials and Methods: This was a hospital-based cross-sectional study conducted at the Department of Pathology, Amala institute of Medical Sciences, Kerala, India during a period of 18 months, from January 2019 to June 2020. In total, 28 specimens of wide local excision with cervical lymph node dissection done for OSCC were enrolled in the study. Small biopsy samples and cases who had undergone neoadjuvant treatment as well as cases of recurrent OSCC were excluded. Clinical details were obtained from the patients’ case files. The immunohistochemical staining for LCs using CD1a and Langerin was done. The distribution of LCs was compared to the tumour grade and lymph node status along with lymphovascular and perineural invasion. Statistical analysis was performed using sample t-test after identifying normality of distribution. The p-value of <0.05 was taken as significant.

Results: Fourteen cases of well differentiated and 14 cases of moderate to poorly differentiated OSCC were selected for the study. The LC distribution in these cases were compared to prognostic factors like histological grade, Lymphovascular Invasion (LVI), perineural invasion, tumour size, depth of invasion, T stage and lymph node status. A significant positive association was observed between the tumour differentiation and peritumoural CD1a positive cell density (p-value: 0.001). Further, a negative association was also established between the lymph node staging and peritumoural CD1a positive cell density (p-value: 0.004). There was no association between the LC density and presence of lymphovascular or perineural invasion in OSCC.

Conclusion: A depleted peritumoural LC density in OSCC reflects poor tumour immunity, associated with higher grade and higher stage of lymph node metastasis. LC density may hence be of prognostic value in OSCC.