A 68-year-old male was diagnosed with acute promyelocytic leukemia (APL). A G-banding chromosomal analysis revealed the co-existence of two clones: one with del(20q) and t(15;17)(q22;q12) and another with del(20q) alone. During the remission of APL following treatment with all-trans-retinoic acid, del(20q) was persistently identified, indicating a diagnosis of cytogenetic abnormalities of undetermined significance (CCAUS) with isolated del(20q). Bicytopenia developed 48 months after the remission of APL. The presence of isolated del(20q) was detected in the G-banding analysis, whereas morphological dysplasia of hematopoietic cells was not confirmed. This case showed indolent progression from CCAUS after the remission of APL to clonal cytopenia of undetermined significance (CCUS). CCUS with isolated del(20q) persisted for 24 months without any finding of hematological malignancies. At the most recent follow-up, targeted capture sequencing showed the U2AF1 S34F mutation. Considerable attention needs to be paid in follow-ups for CCAUS with del(20q) after the treatment of leukemia.

中文翻译：

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从最初诊断为急性早幼粒细胞白血病开始，del（20q）持续存在克隆细胞遗传学异常。

一名68岁的男性被诊断患有急性早幼粒细胞白血病（APL）。G波段染色体分析显示了两个克隆的共存：一个克隆与del（20q）和t（15; 17）（q22; q12），另一个克隆与del（20q）单独。在全反式视黄酸治疗后的APL缓解期间，持续鉴定出del（20q），这表明使用孤立的del（20q）对细胞遗传学异常的重要性未定（CCAUS）进行诊断。APL缓解后48个月，出现了双细胞减少症。在G-带分析中检测到分离的del（20q）的存在，而未证实造血细胞的形态异常。该病例显示，APL缓解后，从CCAUS缓慢发展为意义不明的克隆性血细胞减少症（CCUS）。孤立的del（20q）的CCUS持续24个月，未发现任何血液学恶性肿瘤。在最近的随访中，靶向捕获测序显示U2AF1 S34F突变。白血病治疗后，del（20q）对CCAUS的随访应引起高度重视。