# 异位组织（Ectopic Tissue）

- 器官 / 系统：胸腺 / 免疫系统（thymus / immune-system）
- NTP 数据编号：ntp-0019
- 规范 URL：https://www.labsmart.cn/ntp/thymus-ectopic-tissue.html
- 中文图谱总页锚点：https://www.labsmart.cn/ntp-atlas.html#thymus-ectopic-tissue
- 原始出处：https://ntp.niehs.nih.gov/atlas/nnl/immune-system/thymus/EctopicTissue
- 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
异位组织是指结构正常的组织（如甲状腺、甲状旁腺）出现在异常位置。该病变可为先天性或损伤所致。

## 病变描述（中文）
异位组织是指结构正常的组织（如甲状腺、甲状旁腺）出现在异常位置。该病变可为先天性或损伤所致。异位甲状腺组织可发生于啮齿类动物的胸腺内和/或胸腺邻近部位。Figure 1所示的甲状腺组织由被纤细纤维血管间质分隔的、衬覆上皮的含胶质滤泡组成。甲状腺C细胞偶尔可见于滤泡上皮与甲状腺滤泡基底膜之间。异位甲状旁腺组织偶尔发生于大鼠和/或小鼠胸腺被膜邻近部位或嵌入胸腺被膜内。Figure 2所示的甲状旁腺组织由被薄层纤维血管间质分隔的密集排列、高度折叠、分支状的索和簇状多边形细胞组成。异位甲状旁腺组织是一种不常见的偶然发现，但当其存在时，应将其与胸腺瘤或其他可能的早期或小肿瘤相鉴别。

## 诊断与分级建议（NTP 共识，中文）
异位组织通常是啮齿类动物胸腺内或胸腺邻近部位的偶然发现。当该病变存在时，应予以诊断但不进行分级。存在的异位组织类型（如甲状腺、甲状旁腺）应作为修饰词纳入诊断（如，胸腺 - 异位组织，甲状腺）。

## 英文原文 · Comment
Ectopic tissue is a fragment of structurally normal tissue (e.g., thyroid, parathyroid) in an abnormal location. This lesion can be congenital or the result of an injury. Ectopic thyroid tissue may occur in and/or adjacent to the thymus of rodents. The thyroid tissue shown in Figure 1 consists of epithelial-lined, colloid-containing follicles separated by a fine fibrovascular stroma. Thyroid C cells may occasionally be found between the follicular epithelium and the basement membrane of the thyroid follicles. Ectopic parathyroid tissue occasionally occurs either adjacent to or embedded in the thymic capsule of rats and/or mice. The parathyroid tissue shown in Figure 2 consists of densely packed, highly folded, branching cords and clusters of polygonal cells separated by a thin fibrovascular stroma. Ectopic parathyroid tissue is an uncommon, incidental finding, although when present it should be distinguished from thymoma or other possible early or small tumors.

## 英文原文 · Recommendation
Ectopic tissue is typically an incidental finding in or adjacent to the thymus of rodents. When this lesion is present it should diagnosed but not graded. The type of ectopic tissue present (e.g., thyroid, parathyroid) should be included in the diagnosis as a modifier (e.g., Thymus - Ectopic tissue, Thyroid).

## 配图
- https://www.labsmart.cn/ntp-atlas-images/ntp_0466.jpg
- https://www.labsmart.cn/ntp-atlas-images/ntp_0463.jpg

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