Purpose: To determine the relationship between inflammatory cell types in the microenvironment of papillary thyroid microcarcinoma (PTMC) and prognostic factors.
Methods: The previous diagnoses and subtypes-variants of 163 patients with papillary thyroid microcarcinoma were re-evaluated according to the 2017 WHO classification. The peritumoral lymphocyte, plasma cell, neutrophil, eosinophil, and mast cell density were classified as none (0.24 mm2), mild (0-10/0.24 mm2), moderate (10-50/0.24 mm2), and severe (˃50/0.24 mm2) under 40x magnification and the relationship with prognostic factors was investigated.
Results: There was a statistically significant relationship between tumor capsule invasion (p=0.024) and surgical margin (p=0.049) with mast cell infiltration. A statistically significant relationship was observed between tumor capsule invasion (p=0.0001) and the postoperative disease-free period (p=0.0001) with neutrophil cell infiltration. The postoperative disease-free period of those with neutrophil infiltration was statistically significantly shorter than that of those with no infiltration. The tumor diameter of those with no plasma cells was statistically significantly smaller than that of patients with plasma cells (p=0.003).
Conclusions: Closer follow-up of patients with neutrophils, mast cells, and plasma cells, which have been found to be associated with poor prognostic factors in terms of recurrence, lymph node involvement, and distant metastasis, may increase survival.