INTRODUCTION
Mucosal melanoma is a tumor type with a low incidence rate but it is
highly malignant. Although it is one of the most common subtypes of
melanoma in China [1], only a limited number of cases have been
reported with no support from large datasets. The related literature is
mostly on clinical analysis of head and neck mucosal melanoma [2],
and this has an impact on our understanding and clinical treatment of
this disease. With the development of immunotherapy, researchers are
increasingly studying the immune microenvironment of this tumor type.
Current research is focused on providing theoretical support and
laboratory research on the clinical application of immunotherapy in this
setting. Unlike other types of melanoma, mucosal melanoma does not
benefit significantly from immunotherapy as it has the characteristics
of low tumor mutation load and low lymphocyte infiltration. T cells are
important functional cells in tumor immunity and play an important role
in tumor-related immune processes. CD3 is a specific marker on the
surface of T cells, and CD3 immunohistochemical staining can effectively
evaluate the infiltration level of T cells in tumor tissue [3]. CD8
+ T cells are the main lymphocyte subsets infiltrating the tumor
microenvironment [4]. Previous studies have also confirmed that CD4
+ and CD8 + T lymphocyte infiltration can reflect anti-tumor immune
function to a certain extent [5].
Through analysis of the pathological results from patients with a
previous diagnosis of mucosal melanoma and subsequent treatment, we
aimed to explore the local infiltration of CD3, CD4, and CD8 lymphocytes
in this tumor type. We also examined the relationship of these
lymphocytes to the general characteristics of the disease and the
expression of PD-1 and PD-L1 in the tumor. From this, we hope to further
our understanding of the characteristics of mucinous melanoma in head
and neck, and thus aid clinical practice.