Figure 2. BRAF V600E mutation in HCL but not in other peripheral B-cell neoplasms.
Top panels. Flow cytometry analysis of a HCL patient shows peripheral blood mononuclear cells partly with high forward and side scatter features (black events in the dot plot on the far left), expressing CD19 together with CD11c and with CD103 (red events in the middle and right dot plot, respectively). Direct DNA Sanger sequencing of purified leukemic cells reveals a heterozygous T->A mutation (far right; arrow)
Upper middle panels. Another HCL case analyzed in paraffin sections from a bone marrow biopsy (x 400). Diffuse marrow infiltration by HCL cells (far left; hematoxylin & eosin staining) that display positivity for CD20 (stain in the middle) and for ANXA1 (stain on the right). Purified HCL cells harbor a homozygous/hemizygous T->A mutation (far right; arrow).
Lower middle panels. Splenic Lymphoma/Leukemia Unclassifiable (paraffin sections from a bone marrow biopsy; x 400). Marked marrow infiltration by leukemic cells (far left; hematoxylin & eosin staining), that express CD20 (stain in the middle) but not ANXA1 (stain on the right, where positive myeloid cells act as internal control). Purified leukemic cells do not carry the T->A mutation (far right; arrow).
Bottom panels. Splenic marginal zone lymphoma. Leukemic cells in the peripheral blood smear show the typical morphological features with polar villi (far left; May-Grünwald-Giemsa staining, x 630). At flow cytometry, leukemic cells express CD19 but not CD103 (red events in the left dot plot). These cells only weakly express CD11c and are negative for CD25 (red events in the right dot plot). Leukemic cells do not carry the T->A mutation (far right; arrow).