Parisi Xenia, Ghosh Anindita, Medeiros L Jeffrey
Division of Pathology and Laboratory Medicine Department of Hematopathology The University of Texas MD Anderson Cancer Center Houston Texas USA.
EJHaem. 2025 Feb 12;6(1):e1074. doi: 10.1002/jha2.1074. eCollection 2025 Feb.
The RAM immunophenotype (IP) in acute myeloid leukemia (AML) is defined by blasts with bright CD56 and weak-to-negative CD45, HLA-DR, and CD38 expression. A RAM IP predominantly presents in infants who have "standard-risk disease" under current criteria but, when treated accordingly, have devastatingly high rates of minimal residual disease and relapse with lower 3-year and overall survival rates. However, given the relative rarity of this phenotype, it is neither well-defined nor readily diagnosed.
We reviewed the electronic medical records of our institution from 1990 to 2024 for cases of AML expressing bright CD56 on flow cytometry and identified three cases with a RAM IP. Further, we performed a thorough literature search and reviewed impactful studies on pediatric AML and case/series reports of patients with a RAM IP, leading to the identification of 38 more cases.
A total of 41 patients were collected. These patients were toddler age (1-3 years) with an equal sex distribution and clinically presented with low circulating blasts and cytopenias. Blasts were typically French-American-British M0 or M7. Immunophenotypically, CD33 and CD117 showed positivity in >90% of cases, with CD19, CD34, CD41, and CD42b, frequently positive. Half of the cases were positive for CD7 and CD61. T-cell/myeloid markers were rare, except for cytoplasmic CD3, seen in 1/3, apparently correlating with fusions. Gains in chromosomes 21, 13, and 8 and fusions were frequent.
AML with a RAM IP has a poor prognosis. This study offers a detailed characterization of the clinicopathologic patterns associated with this rare entity, which may help formulate the most appropriate diagnostic approach.
急性髓系白血病（AML）中的RAM免疫表型（IP）由表达明亮CD56且CD45、HLA-DR和CD38表达为弱阳性至阴性的原始细胞定义。RAM IP主要出现在按照当前标准属于“标准风险疾病”的婴儿中，但按此标准治疗时，微小残留病和复发率极高，3年生存率和总生存率较低。然而，鉴于这种表型相对罕见，其定义尚不明确，也不易诊断。
我们回顾了1990年至2024年我院机构的电子病历，以查找流式细胞术显示表达明亮CD56的AML病例，并确定了3例具有RAM IP的病例。此外，我们进行了全面的文献检索，回顾了关于儿童AML的有影响力的研究以及具有RAM IP患者的病例/系列报告，从而又确定了38例病例。
共收集到41例患者。这些患者为幼儿期（1至3岁），性别分布均衡，临床上表现为循环原始细胞数量低和血细胞减少。原始细胞通常为法美英分型的M0或M7。免疫表型上，CD33和CD117在>90%的病例中呈阳性，CD19、CD34、CD41和CD42b也经常呈阳性。一半的病例CD7和CD61呈阳性。T细胞/髓系标志物罕见，除了1/3的病例中可见胞质CD3，这显然与融合有关。21号、13号和8号染色体的增益以及融合很常见。
具有RAM IP的AML预后不良。本研究详细描述了与这种罕见实体相关的临床病理模式，这可能有助于制定最合适的诊断方法。
