# 细胞增多（Hypercellularity）

- 器官 / 系统：骨髓 / 造血系统（bone-marrow / hematopoietic-system）
- NTP 数据编号：ntp-0433
- 规范 URL：https://www.labsmart.cn/ntp/bone-marrow-hypercellularity.html
- 中文图谱总页锚点：https://www.labsmart.cn/ntp-atlas.html#bone-marrow-hypercellularity
- 原始出处：https://ntp.niehs.nih.gov/atlas/nnl/hematopoietic-system/bone-marrow/Hypercellularity
- 授权：美国联邦政府作品，公有领域；引用请标注 NTP Nonneoplastic Lesion Atlas
- 适用说明：仅供科研使用，不用于临床诊断

## 一句话结论
骨髓细胞密度（bone marrow cellularity）指造血细胞相对于骨髓脂肪的数量或百分比。

## 病变描述（中文）
骨髓细胞密度（bone marrow cellularity）指造血细胞相对于骨髓脂肪的数量或百分比。已有研究表明，2月龄大鼠的正常骨髓（胸骨和股骨）含80%或以上的造血细胞，其余细胞大部分由脂肪细胞组成；4–16月龄大鼠的正常骨髓含约60–75%的造血细胞。已知随着啮齿类动物及其他物种衰老，正常骨髓细胞密度降低，并伴有脂肪细胞的相对增多。此外，2岁大鼠的动物间变异大于4–16月龄大鼠。一般而言，同年龄小鼠的总体骨髓细胞密度高于大鼠。骨髓细胞密度的变化可累及所有或单个细胞系。红系或髓系细胞系的变化可能使M:E比例相对于对照组发生偏移。据报道，大鼠和小鼠的正常M:E比例为0.80至2.79，平均为1.5，且取决于品系和年龄，这强调了将受试动物与同期对照进行比较的重要性。组织学切片可对M:E比例进行粗略估计，以辅助评估细胞密度，而细胞学制片则用于更精确地测定M:E比例并评估成熟同步性的细微变化。当受试动物与同期对照相比造血细胞相对于脂肪细胞增多时，记录为骨髓细胞密度增高（hypercellularity）（Figure 2、Figure 4、Figure 5）。细胞密度增高可作为对化合物给药的非特异性或直接（例如给予细胞因子时）反应而发生，但更常见的是由于外周血细胞减少、外源物质所致骨髓损伤的恢复或炎症所引起的再生性反应。例如，细胞密度增高可继发于脓毒症，或由失血、溶血性贫血或血小板消耗/破坏所致。刺激某一细胞系产生增多可引起其他细胞系产生增加，导致骨髓细胞密度总体增高。在显著（marked）细胞密度增高时，造血细胞可充满整个骨髓腔，甚至延伸穿过滋养孔。

## 诊断与分级建议（NTP 共识，中文）
为评估骨髓细胞密度，即造血细胞相对于骨髓脂肪的百分比，必须将受试动物的骨髓与同部位同期对照骨髓进行比较。细胞密度的变化应记录并分级，分级方案应在文字描述中说明。分级基于与研究病理学家所定义的同期对照相比的变化程度。虽然细胞密度的变化可能由特定细胞系的变化所致，但仅凭组织学评估可能难以识别这一点。如果特定细胞系的变化并不明确，则仅记录为细胞密度增高更为恰当。不宜诊断同时存在的脂肪细胞减少，因为其被视为继发于造血细胞增多。记录骨髓细胞密度变化时，不应使用临床、解释性或诊断性术语（例如“增生（hyperplasia）”），而应使用本文所述的描述性术语“细胞密度增高（hypercellularity）”。当细胞密度变化需要进一步解释或与受试物相关时，应在病理学文字描述中对其进行描述和解释，此时解释性术语或诊断（如红系增生（erythroid hyperplasia））可结合其他组织学所见、可获得的血液学数据、生前所见以及骨髓细胞学（例如M:E比例）或流式细胞术所见加以使用。

## 英文原文 · Comment
Bone marrow cellularity refers to the amount or percentage of hematopoietic cells relative to marrow fat. It has been shown that normal bone marrow (sternum and femur) of rats 2 months of age contains 80% or more hematopoietic cells, with the majority of the remaining cells composed of adipocytes; normal bone marrow of rats 4–16 months of age contains approximately 60–75% hematopoietic cells. It is known that as rodents and other species age, normal bone marrow cellularity decreases and is accompanied by a relative increase in adipocytes. In addition, rats 2 years of age show greater interanimal variability than do 4- to 16-month-old rats. In general, mice have higher overall bone marrow cellularity than do rats of the same age. Changes in bone marrow cellularity may involve all or individual cell lines. Changes in the erythroid or myeloid cell lines may shift the M:E ratio relative to controls. Normal M:E ratios of rats and mice are reported between 0.80 and 2.79, with an average of 1.5, and are dependent on strain and age, stressing the importance of comparing treated animals with concurrent controls. Histologic sections allow for a rough estimate of the M:E ratio to aid in the evaluation of cellularity, while cytologic preparations are needed for a more precise determination of the M:E ratio and evaluation of subtle changes in synchrony of maturation. Hypercellularity of the bone marrow is recorded in treated animals when there is an increase in hematopoietic cells relative to adipocytes compared with concurrent controls ( Figure 2 , Figure 4 , and Figure 5 ). Hypercellularity may occur as a nonspecific or direct (e.g., with cytokine administration) response to compound administration but more commonly is due to a regenerative response as a consequence of decreases in peripheral blood cells, recovery from a xenobiotic-induced bone marrow injury, or inflammation. For example, hypercellularity may be secondary to sepsis or a result of blood loss, hemolytic anemia or platelet consumption/destruction. Stimulation to produce more of one cell line can cause increased production of other cell lines, causing an overall increase in bone marrow cellularity. With marked hypercellularity, hematopoietic cells may fill the entire marrow space, even extending through the nutrient foramina.

## 英文原文 · Recommendation
To evaluate bone marrow cellularity, that is, the percentage of hematopoietic cells relative to marrow fat, bone marrow from treated animals must be compared with same-site concurrent control bone marrow. Changes in cellularity should be recorded and graded, and the grading scheme should be described in the narrative. Grading is based on the degree of change compared with concurrent controls as defined by the study pathologist. While changes in cellularity may be due to a change in a specific cell line, it can be difficult to appreciate this with histologic evaluation alone. If changes in specific cell lines are not explicitly clear, it is more appropriate to record the changes as just hypercellularity. It is not appropriate to diagnose the concurrent decrease in adipocytes because it is considered secondary to the increase in hematopoietic cells. Clinical, interpretative, or diagnostic terms (e.g., “hyperplasia”) should not be used when recording changes in bone marrow cellularity but rather the descriptive term “hypercellularity” as discussed herein. When changes in cellularity warrant further explanation or are treatment related, they should be described and interpreted in the pathology narrative, where interpretive terms or diagnoses, such as erythroid hyperplasia, can be used in context with other histologic findings, available hematologic data, in-life findings, and bone marrow cytologic (e.g., M:E ratio) or flow cytometric findings.

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