Detection of tumor-associated tryptase-positive mast cells in sporadic medullary thyroid carcinoma

BACKGROUND: There are currently no published studies on the role of mast cells in the pathogenesis of sporadic medullary thyroid carcinoma. However, their involvement in the progression of a variety of epithelial malignant neoplasms has been demonstrated. Furthermore, mast cell count may be an independent predictor of long-term progression-free survival in patients with pancreatic neuroendocrine tumors. AIM: The work aimed to evaluate the potential of immunohistochemical detection of mast cells in the tumor microenvironment in sporadic medullary thyroid carcinoma. METHODS: Histological specimens of sporadic medullary thyroid carcinoma were assessed using immunohistochemical detection of tryptase in mast cells. A convolutional neural network (CNN) model was then trained to segment positively stained cells, followed by quantitative analysis of the results. RESULTS: Several potentially clinically significant parameters were identified, including correlations between mast cell count in the thyroid stroma and age; correlations between intratumoral mast cell count and T stage according to the TNM (8th edition) classification; and patterns of mast cell colocalization with other cells of the tumor microenvironment. CONCLUSION: The study confirmed the presence of mast cells in the stroma of medullary thyroid carcinoma and revealed quantitative differences depending on tumor size. The observed active interactions of mast cells with atypical cells of sporadic medullary thyroid carcinoma and other components of the tumor microenvironment are a significant criterion for interpreting the biological effects of mast cells in this tumor type. These findings warrant further analysis to develop diagnostic algorithms and improve prognostic accuracy.