Cytology and FC of MCL. a Smear showing a monomorphous population of small-medium-sized lymphocytes. Nuclei have coarse chromatin, evident membrane irregularities, and small nucleoli. Diff-Quik stain. ×430. b-d FC histograms showing CD5/CD19 coexpression(b), CD19 positivity and CD23 negativity (c), and κ light chain restriction(d).