工作日每天早上7:30~8:00, 浙江省人民医院皮肤科的医生们就开始英文专著早读会。我们发布中英文报告，有兴趣的医生可以和我们一起学习。

Histologically, terminal hairsprogressively transform to vellus hairs（Figs 22.49,22.50）.There is adecrease in the size of the dermal papilla, bulb size, and hair shaft diameter.Although the total hair count is normal, it will appear reduced if the count istaken at the junction of the dermis and subcutaneous fat, since by definitionterminal hairs are diminished in number. Even though these changes may also beseen in vertical sections (Fig. 22.51), they are more difficult to interpretand quantify.

组织学上终毛进行性转化为毳毛。真皮乳头，毛囊球部以及毛干直径大小会减少。虽然毛囊总数是正常的，但因为终毛数量减少以至于真皮和皮下脂肪交界水平的毛囊计数减少。尽管纵切面中也可见到这些变化，但是他们更难以解释和量化。

Androgenic alopecia: almost all hairfollicles are miniaturized and sebaceous glands appear prominent. Masson'strichrome stain.

雄性脱发:几乎所有的毛囊是小型化和皮脂腺显得突出。 Masson三色染色。

Androgenicalopecia, follicular unit: the miniaturization process is complete and noterminal follicles are left.

雄性脱发：毛囊单位:小型化过程完成，终端毛囊残留。

Androgenic alopecia, vertical section: onlytwo hair follicles reach the subcutaneous fat. The rest are miniaturizedfollicles in the mid dermis.

雄性脱发：垂直部分:只有两个毛囊达到皮下脂肪。余下的是在真皮中层的小型化毛囊。

Along with these changes, there is areduction in the duration of the hair follicle cycle at the expenses of theanagen phase. Therefore in patients with evolving androgenetic alopecia, orwhen it is fully established, it is very common to find an increment in thenumber of catagen and telogen follicles. The histological picture of the femalevariant is identical.

随着这些变化,在毛囊周期中的生长期的持续时间会减少。因此，在雄激素脱发进展期患者,或者当诊断完全确立时，找到生长中期和静止期毛囊数量的增加是很常见的。女性类型的组织学图片是相同的。

A mild to moderate lymphocytic inflammatorycell infiltrate frequently surrounds the upper third of the hair follicle. Theminiaturization of hair follicles affects the whole of the hair follicleincluding, finally, the arrector pili muscle and the sebaceous gland.

在毛囊的上1/3部分的周围常常有轻度到中度的淋巴细胞浸润。毛囊的小型化影响整个毛囊,包括最后，影响到竖毛肌和皮脂腺。

In the deeper sections, hair bulbs are presentat different depths, and focally they may be completely absent, only follicularstellae remaining. These stellae are seen in a variety of conditions andreflect either miniaturized follicles or else follicles that have enteredcatagen or telogen stage. 

As the stellae mature, they become lessvascularized, presenting as fibrous scars with a blue-gray hue. In lateandrogenic alopecia the stellae becomes abnormally thick and could impede thegrowth of the follicle (Fig. 22.52).

在更深的切片中，毛球出现在不同的深度，在局部可以完全消失，仅留有毛囊索。毛囊索可见于不同的情况，反应了毛囊的微小化，或是毛囊进入了退行期或休止期。随着毛囊索成熟，其中血管减少，毛囊索最终成为灰蓝色的纤维疤痕。在雄脱末期，毛囊索变得异常厚，可能阻碍毛囊的生长

Androgenic alopecia, follicular stellae (a,B): as the follicles undergo miniaturization they leave behind numerousfollicular stellae. 雄性脱发：毛囊索卵泡 (a,B): 随着毛囊小型化，遗留了许多毛囊索。

The terminal to vellus hair ratio (7:1) ismuch reduced and varies from 1:1 or even 1:2. Although initially the number ofhair follicles is normal, in longstanding disease there can be a realreduction. A biopsy may therefore show a decrease in hair follicle density inaddition to diminution in size of the individual hair follicles. Sometimes theappearances may be more suggestive of a scarring alopecia (Fig. 22.53).

终毛/毳毛的比例从7：1可以大幅减少到1：1甚至1：2。尽管在疾病的初始阶段毛囊的数量是正常的，但随着病程的发展，其数量会减少。因此活检会显示除了毛囊缩小，还有毛囊密度的降低。有时候表现更像疤痕性脱发。

Androgenic alopecia, final stage:follicular units and miniaturized hair follicles are rare. In this advancedstage connective tissue has almost completely replaced follicular structuresand the appearances resemble a scarring alopecia.

雄性脱发：最后阶段:毛囊单位和小型毛囊是罕见的。在这个进展阶段结缔组织几乎已经完全取代了毛囊结构，表现像疤痕性脱发。

Differential diagnosis

The most important differential diagnosesare diseases which present with diffuse nonscarring alopecia including telogeneffluvium, alopecia areata, and trichotillomania.

首先应与弥漫性非疤痕形成性脱发鉴别：包括休止期脱发，斑秃和拔毛癖。

Although androgenetic alopecia may showincreased numbers of telogen hairs, telogen effluvium is clinically morediffuse and there are no miniaturized hair follicles. It is important, however,to note that both diseases may present simultaneously and that chronic telogeneffluvium may uncover occult androgenetic alopecia.

虽然雄激素源性脱发可以出现休止期毛发数量增加，但临床上休止期脱发更加弥漫，并且没有毛囊的微小化。重要的是这两个病可以同时发生，慢性休止期脱发可能会提示隐匿的雄激素源性脱发。

Alopecia areata may show miniaturized hairfollicles, particularly in very chronic cases. Characteristically, however,there is a major increase in the number of hair follicles in catagen, telogen,and anagen and usually a sparse peribulbar lymphocytic infiltrate is present,sometimes accompanied by eosinophils. Without adequate clinical information,distinction may be impossible.

斑秃可能显示小型毛囊,尤其是慢性病例。然而典型的是，生长中期,静止期的毛囊数量明显增加。同时有毛球周围淋巴细胞浸润。有时还伴有嗜酸性粒细胞。没有足够的临床信息,鉴别是几乎是不可能的。

In trichotillomania there are increasednumbers of hair follicles in catagen and telogen but in addition there istrichomalacia (short, incompletely keratinized hairs), pigmented casts, anddistortion of hair shafts.

在拔毛发癖中，退行期和静止期毛囊数量增加，另外还有毛软化(短,没有完全角化的头发)，色素管型和毛发扭转。

（浙江省人民医院皮肤科 丁扬医生译）2017-11-9