# 萎缩（Atrophy）

- 器官 / 系统：胸腺 / 免疫系统（thymus / immune-system）
- NTP 数据编号：ntp-0027
- 规范 URL：https://www.labsmart.cn/ntp/thymus-atrophy.html
- 中文图谱总页锚点：https://www.labsmart.cn/ntp-atlas.html#thymus-atrophy
- 原始出处：https://ntp.niehs.nih.gov/atlas/nnl/immune-system/thymus/Atrophy
- 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
萎缩（atrophy）的特征是胸腺体积和重量减小，继发于胸腺淋巴细胞耗竭。正常胸腺通常具有大小相近的小叶、紧密贴附的被膜、与髓质相比细胞密集的皮质、清晰的皮髓质（corticomedullary，CM）交界，以及约1:1:1的皮质与髓质比值（两个皮质对髓质）（Figure 1、Figure 2）。

## 病变描述（中文）
萎缩（atrophy）的特征是胸腺体积和重量减小，继发于胸腺淋巴细胞耗竭。正常胸腺通常具有大小相近的小叶、紧密贴附的被膜、与髓质相比细胞密集的皮质、清晰的皮髓质（corticomedullary，CM）交界，以及约1:1:1的皮质与髓质比值（两个皮质对髓质）（Figure 1、Figure 2）。在极轻微（minimal）萎缩时（Figure 3、Figure 4），皮质可变薄且不规则，随着病变进展为轻微（mild）（Figure 5，Figure 6）和中度（moderate）（Figure 7、Figure 8），CM分界逐渐消失。当病变为显著（marked）时（Figure 9、Figure 10），皮质和髓质的细胞密度降低，CM交界可能不再明显。髓质可能显得比皮质大，胸腺各区的细胞学外观可能呈现反转，即皮质因细胞密度降低而呈淡嗜酸性，髓质因细胞密度增加而呈深嗜碱性。胸腺萎缩可能受营养、肾上腺皮质功能亢进以及激素水平变化（如性激素或生长激素）的影响。胸腺萎缩必须与胸腺退化（involution）相鉴别。年龄相关退化是一种渐进的、不可逆的变化，可能与性类固醇循环有关。除皮质细胞密度降低外，正常退化还可能包括CM交界模糊、被膜和实质的脂肪细胞浸润、髓质上皮细胞突出度增加和/或增生，以及髓质内形成滤泡样B细胞聚集。与年龄无关的萎缩通常由毒性损伤引起，去除致病因素后可能可逆。

## 诊断与分级建议（NTP 共识，中文）
胸腺萎缩出现时，应当诊断并分级。如果萎缩仅累及一叶或呈局限性，应在病理学描述中讨论。诱发性萎缩必须与胸腺正常退化相鉴别。具有潜在治疗相关胸腺萎缩的动物应与年龄和性别匹配的同批对照动物进行比较。动物的年龄和明确的剂量-反应关系将有助于区分胸腺萎缩与正常退化。

## 英文原文 · Comment
Atrophy is characterized by reduced thymus size and weight secondary to thymic lymphocyte depletion. A normal thymus typically has similarly sized lobules, a closely apposed capsule, a densely cellular cortex compared with the medulla, a distinct corticomedullary (CM) junction, and a cortex to medulla ratio of ~1:1:1 (two cortices to the medulla) ( Figure 1 and Figure 2 ). With minimal atrophy ( Figure 3 and Figure 4 ), the cortex may become thinner and irregular, with progressive loss of the CM demarcation as the lesion becomes mild ( Figure 5 , Figure 6 ) and moderate ( Figure 7 and Figure 8 ). As the lesion becomes marked ( Figure 9 and Figure 10 ), cellularity of the cortex and medulla is decreased, and the CM junction may no longer be apparent. The medulla may appear larger than the cortex, and the cellular appearance of thymic compartments may appear reversed, with a pale eosinophilic cortex due to reduced cellularity and a darkly basophilic medulla due to increased cellularity. Thymic atrophy may be influenced by nutrition, adrenocortical hyperactivity, and changes in hormone levels (e.g., sex or growth hormones). Thymic atrophy must be differentiated from thymic involution. Age-related involution is a gradual, nonreversible change, likely associated with sex steroid circulation. In addition to decreased cortical cellularity, normal involution may include blurring of the CM junction, adipocyte infiltration of the capsule and parenchyma, increased prominence and/or hyperplasia of medullary epithelial cells, and formation of follicular-like B-cell aggregates in the medulla. Atrophy that is unrelated to age is generally caused by toxic insult and is potentially reversible with removal of the inciting agent.

## 英文原文 · Recommendation
When present, atrophy of the thymus should be diagnosed and graded. If atrophy involves only one lobe or is localized, this should be discussed in the pathology narrative. Induced atrophy must be differentiated from normal involution of the thymus. An animal with potential treatment-related thymic atrophy should be compared with age- and sex-matched concurrent controls. Age of the animal and a clear dose-response relationship will help differentiate between thymic atrophy and normal involution.

## 配图
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