A 72-year-old man is found to have asymptomatic lymphocytosis (WBC 15 × 10⁹/L) on routine CBC. Flow cytometry confirms CD5+, CD19+, CD20-dim, CD23+ B-cells with kappa light-chain restriction. FISH panel is performed as part of diagnostic workup. The cytogenetic abnormality marked **B** in the diagram is identified. Which of the following best describes the prognostic significance and immediate management approach for this patient?

Question

Accepted Answer

C. Isolated del(13q14) is the most favorable cytogenetic abnormality in CLL with median overall survival >11 years; watch-and-wait is appropriate for asymptomatic early-stage disease. ## Why option 1 is right

The structure marked **B** represents isolated del(13q14), which is the most common (~55% of CLL cases) and most favorable cytogenetic abnormality in the Döhner hierarchical FISH panel. The 13q14.3 deletion removes the miR15a/miR16-1 microRNA cluster, leading to BCL2 overexpression and impaired apoptosis, yet paradoxically confers the best prognosis with median overall survival exceeding 11 years. For asymptomatic early-stage disease (Rai 0–II, Binet A), watch-and-wait is the standard of care per iwCLL 2018 guidelines, as early therapy provides no survival benefit. Treatment is reserved for progressive cytopenias, massive/symptomatic lymphadenopathy, lymphocyte doubling time <6 months, B-symptoms, or refractory autoimmune cytopenia.

## Why each distractor is wrong

- **Option 2**: Del(13q14) is the MOST favorable, not intermediate. Trisomy 12 (median OS 9–10 years) has worse prognosis than isolated del(13q14). FCR (fludarabine–cyclophosphamide–rituximab) is now largely obsolete and is not indicated for asymptomatic early-stage disease regardless of cytogenetics.

- **Option 3**: Del(13q14) does NOT involve TP53 loss; that is del(17p), which is the worst prognostic abnormality (median OS 3 years) and requires BTK inhibitor or venetoclax therapy. Isolated del(13q14) does not mandate immediate treatment in asymptomatic patients.

- **Option 4**: Del(13q14) is a hallmark of CLL, not mantle cell lymphoma. Mantle cell lymphoma is characterized by t(11;14) (marked **C** in the diagram). Rituximab monotherapy is not standard first-line therapy for CLL.

**High-Yield:** Isolated del(13q14) = best CLL prognosis (>11 yr median OS) = watch-and-wait in early stage; del(17p) = worst prognosis (3 yr) = avoid chemo, use BTKi/venetoclax.

[cite: Döhner H, et al. NEJM. 2000;343(26):1910–1916; Hallek M, et al. Blood. 2018;131(5):487–495 (iwCLL 2018)]

Answer

A. Isolated del(13q14) indicates mantle cell lymphoma transformation; rituximab monotherapy should be initiated immediately

Answer

B. Del(13q14) is associated with TP53 loss and requires immediate BTK inhibitor therapy regardless of disease stage

Answer

D. Del(13q14) confers intermediate prognosis similar to trisomy 12; immediate chemotherapy with FCR is indicated to prevent progression

Explanation

Why option 1 is right

Why each distractor is wrong

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