Laboratory tests are not usually necessary for the diagnosis but they may be of value in detecting associated conditions, particularly autoimmune disease. The hair-pull and hair-pluck tests show an increase in the number of telogen and dystrophic anagen hairs. The remaining anagen hairs are dystrophic because the continuous inflammatory process results in premature transformation into catagen and telogen phase. This abbreviatedgrowth cycle results in many terminal follicles with poorly keratinized short stems that break readily (exclamation mark hairs). Histologically, alopecia areata is characterized by three basic features:

1. normal numbers of follicular units and hair follicles in the initial stages with loss of follicles in the recalcitrant and most chronic phases；

2. an increase in the number of catagen and telogen follicles；

3. a lymphocytic infiltrate of variable severity affecting the bulbs of the   anagen follicles and the catagen and telogen follicular stellae.

实验室检查通常不是诊断斑秃所特需的，但是可以帮助发现与其相关的疾病，尤其是自身免疫性疾病。拉发试验和拔发试验显示休止期和营养不良的生长期头发数量增加。残留的生长期毛发生长不良，这是因为持续的炎症导致生长期毛囊提前进入退行期和休止期。这种变短的生长周期是许多终毛毛囊毛干角化不全，易于折断。组织学上，斑秃有三个基本的特征性表现：

• 毛囊单位和毛囊的数量正常；

• 退行期和休止期的毛囊的数量增加；

• 在生长期毛囊的毛球和退行期与休止期的毛囊锁周围有不同程度的淋巴细胞浸润。

It is important to remember that the histopathological features depend on the stage of the disease.

需要注意的是，斑秃的组织病理表现随疾病的发展阶段而不同。

All the changes in alopecia areata described in vertical sections are better observed in horizontal sections (Fig.22.65).This is particularly true of hair bulb lymphocytic infiltration (Fig. 22.66). Nevertheless, the inflammatory infiltrate is not always visible. The frequency with which this and otherhistological changes are observed depends on the stage of the illness when the biopsy is performed. In each particular affected area the established lesion isobserved in the center of the patch of alopecia and the more active features are evident at the edge adjacent to the normal scalp.

横切面比纵切面中更易观察的斑秃的病理变化（图22.65）。尤其是毛球部的淋巴细胞浸润（22.66）。然而，炎症细胞浸润并不会总被看到。这种及其他病理学上改变被观察到几率取决于活检时疾病所处的阶段。脱发斑的中心是充分发展的皮损，而在脱发斑边缘靠近正常头皮的部位则是活动期的损害。

图22.65 斑秃：(A)纵切面显示毛囊数量的明显减少，可以看到毛球周围淋巴细胞浸润；（B）横切面显示正常数量的毛囊，左上侧的毛囊处于退行期和休止期。

Early stages

In the early stages of the disease there is an increase in the number of  catagen and telogen follicles. Telogen counts exceed those seen in telogen effluvium (Fig.22.67). The follicles show a variable inflammatory       lymphocytic infiltrate in the peribulbar region (Figs22.66,22.68). This may occasionally be very mild, evenin more active lesions. This is        particularly noticeable in the atypical, diffuse, and ophiasic forms.76 Sometimes plasma cells are observed. The presence of eosinophils in the stellae and within the hair bulbshas been described as an early and typical feature (Fig. 22.69).77 The earliest changes are loss of structural integrity of the centrally located supramatrical upper bulbar region and shrinkage of hair bulbs.78 The hair matrix is infiltrated by lymphocytes and there is also pigment incontinence, matrix cell necrosis, and vacuolar damage.79 The inflammatory infiltrate is especial lyprominent in terminal hair follicles, the bulbs of which are located in thesubcutaneous tissue (Fig. 22.70). Pigment incontinence may be very conspicuous and lead to the formation of clumps of melanin pigment (pigmentcasts) in the distorted hair bulb and follicular streamer (Fig. 22.71).80 The infiltrate is composed

of an admixture of CD4+ and CD8+ T lymphocytes.  studies have shown deposits of C3, IgG, and IgM along the basement membrane of the        inferior part of the hair follicle. Once the follicle enters catagen stage and progresses to telogen the inflammatory cell infiltrate decreases. lymphocytic infiltration is accompanied by progression to catagen and telogen. Following this, the follicle rapidly returns to anagen and the cycle repeats itself. Due to this continuous cycle and the accompanying inflammatory process, the follicles go through two important morphological changes:

• trichomalacia characterized by short, incompletely keratined (pencilpoint) hairs which are susceptible to trauma；

• mini aturization of some anagen follicles.

早期

在本病早期，退行期和休止期毛囊的数量增加，休止期毛囊数量比休止期脱发中的还要多（图22.67）。在毛囊的毛球周围有不同程度的炎症性淋巴细胞浸润（图22.66,22.68）。即便是在病情活动皮损内，炎症浸润也可以是很轻微的。这种现象在非典型性、弥漫性和匍行簇集性类型中尤为明显。有时候也可以看到浆细胞浸润。早期的典型特征是在毛囊索和毛球内部出现嗜酸性细胞（图22.69）。最早的变化是位于中央毛囊球区域上部毛母质上结构完整性的缺失和毛囊球的收缩。毛母质中有淋巴细胞浸润，并出现色素失禁、毛母质细胞凋亡和空泡化改变。炎症浸润在终毛毛囊尤为显著，终毛毛球位于皮下组织中（图22.70）。色素失禁可以是非常明显的，在弯曲的毛囊球以及毛囊条索中可以导致黑色素的凝集形成（22.71）。炎症细胞是CD4+和CD8+T淋巴细胞的混合。研究显示炎症毛囊下端基底膜可以看到C3、IgG、IgM的沉积。毛囊进入退行期至休止期后，炎症细胞浸润即逐步减少。随后，毛囊迅速重回生长期，然后重复循环。由于这个过程不断循环，并伴有炎症过程，因此毛囊会发生两个中重要的形态学变化：

• 毛软化：特征是毛发变短，角化不充分（铅笔样），容易折断;

• 一些生长期毛囊的微小化。

图22.67 斑秃：休止期毛囊的球的纵切面，在残余毛囊中可以看到炎症细胞浸润

图22.68 斑秃：退化中的毛囊。上图为纵切面。右侧的毛囊可以看到炎症细胞浸润，毛干也同时受累

图22.69 斑秃，毛囊索：伴有嗜酸性细胞的淋巴细胞浸润

图22.70 斑秃 上半部分毛囊球为淋巴细胞所浸润，转化为一个休止期毛囊，并伴有嗜伊红基底膜；下半部分显示为伴有淋巴细胞浸润和色素失禁的毛囊索。所有的显微下图片都是在皮下脂肪组织水平下拍摄。

图22.71 斑秃，毛囊索：可以看到少量的炎症细胞浸润，大量的噬黑素细胞

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未完待续  （浙江省人民医院皮肤科 皇幼明医生译）2017-11-15