Alisha Relan; Sabina Desar; Brian Dunnette; Ryan Shanley & Alessio Giubellino

Inflammatory infiltrates are frequently present in melanocytic lesions, with different distribution and composition. Much attention has been devoted to tumor-infiltrating lymphocytes (TIL) in the tumor microenvironment, establishing their prognostic and predictive value in many malignancies, including melanoma. However, lymphocytes, albeit the most numerous and consistent presence, constitute only part of the immune microenvironment. Other inflammatory cells, including neutrophils, plasma cells, eosinophils and mast cells, are found in melanoma and other melanocytic lesions.Few studies offer a detailed count of these inflammatory infiltrates across the spectrum of melanocytic lesions. By using whole slide image analysis and open source software, in the present study we report the enumeration of different inflammatory infiltrates in benign melanocytic nevi, dysplastic nevi, melanoma in situ and invasive malignant melanomas. Significant higher numbers of plasma cells and neutrophils were observed in melanoma. These results indicate that composition of the inflammatory infiltrate may contribute to the diagnostic algorithm of melanocytic lesions.

KEY WORDS: Inflammatory cells; Lymphocytes; Neutrophils; Plasma cells; Nevi; Melanoma.

RELAN, A.; DESAR, S.; DUNNETTE, B.; SHANLEY, R. & GIUBELLINO, A. Inflammatory infiltrates in melanocytic lesions. Int. J. Morphol., 39(2)512-519, 2021.