CD19 and neoplasm: Two months later, a bone marrow trephine biopsy (Case‐06‐HGBCL) revealed infiltration of medium‐ to large‐sized immature lymphoid cells that were positive for CD19, CD79a, CD43, BCL2, and TdT (moderate to strong positivity in ~80% of tumour cells), CD20 (partial) and MUM1 (partial), but negative for CD10, CD34, CD117, and BCL6.