Microscopic Description and Lab Work-Up

Histologic sections show diffuse infiltration of the tissue by intermediate-large lymphocytes with pleomorphic nuclei, one to several prominent nucleoli and frequent mitotic figures.   The malignant cells are admixed with a small number of small lymphocytes with mature cytological features.  Many macrophages with ingested apoptotic tumor cells are found throughout the sections, imparting a "starry sky" pattern. Malignant cells are found at the marked deep margin. Touch preps show many pleomorphic intermediate-large cells, admixed with a small number of mature lymphocytes. The malignant cells have basophilic cytoplasm without cytoplasmic vacuoles.

Immunohistochemical stains performed on block 1C, with adequate controls, show that the malignant cells are positive for CD10, and CD20, but are negative for bcl-1, bcl-2, CD3, CD30, and ALK-1. Ki-67 shows a proliferation rate of about 90%.  EBV-LMP is negative.

Immunophenotyping by flow cytometry in gate#1 shows a predominant B-cell population (>90% of the cells analyzed) that is positive for CD10, CD19, CD20, CD22, and surface lambda light-chain restriction.  They are negative for CD5, and CD23. These B-cells have intermediate-large nuclear size (based on forward-scatter signal). Analysis in gate #2 shows a small T-cell population with no aberrant loss or aberrant expression of T-cell markers and a normal B-cells population.

(Diffuse Large B-cell Lymphoma)