Melanoma tumour infiltrating lymphocytes, light micrograph. Tumour infiltrating lymphocytes (TIL) in melanoma convey important prognostic information. A dense lymphocytic infiltrate within and around melanoma appears to correlate with better prognosis. The lymphocytic response is subdivided into three categories; brisk, non-brisk, or absent. Brisk: TILs are present throughout the vertical growth phase or across the entire base of the tumour. Non-brisk: TILs focally infiltrate the tumour. Absent: TILs are absent altogether OR they are present but do not infiltrate the tumour. This light photomicrograph shows brisk response. The melanoma cells (larger cells, many of them containing brown pigment) are intimately admixed with lymphocytes (smaller cells with hyperchromatic nuclei).