To ensure that all “t”’s were dashed, and all “I”’s dotted (so to speak), I elected to run specially staining on the tissue samples called immunohistochemistry staining. Immunohistochemistry staining is a newer technique where the coloured part of the stain binds only to certain structures. This type of stain allows pathologists to identify between two objects that look identical on regular staining. As most of the inflammatory cells from the first stain were lymphocytes, the special stains were used to identify T lymphocytes versus B lymphocytes. This is where the diagnosis becomes more suggestive for lymphoma. As indicated in the 2 slides, over 95% of the lymphocytes stain positive for T-cell origin.
Why is this important? In inflammatory disease, we expect both T and B cells to be contributing so we should see mixed staining results. As cancers reflect abnormal growth of one cell type, to see mostly T cells is not good. In Tigger's slides, we can see very few dark blue staining B-cells compared to a sample containing lots of dark brown T-cells.