A 68-year-old Indian man undergoes routine CBC for hypertension follow-up. His WBC is 12 × 10⁹/L with absolute lymphocytosis. Peripheral blood smear shows numerous cells marked **A** — fragile, crushed lymphocyte remnants with naked nuclei appearing as lavender-pink shadows. Flow cytometry confirms CD5+, CD19+, CD23+, and kappa light chain restriction. Which of the following is the MOST IMPORTANT diagnostic and prognostic distinction between this patient's condition and Mantle Cell Lymphoma?