Miteva Mariya, Misciali Cosimo, Fanti Piero A, Tosti Antonella
Department of Dermatology and Cutaneous Surgery, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA.
J Cutan Pathol. 2012 Jun;39(6):596-602. doi: 10.1111/j.1600-0560.2012.01896.x.
Alopecia areata (AA) incognito represents a variant of AA characterized by acute diffuse hair thinning. Dermoscopy shows yellow dots and short regrowing hairs. The differential diagnosis with telogen effluvium (TE) and androgenetic alopecia may be difficult.
In order to establish histopathological criteria for the diagnosis of AA incognito, we evaluated retrospectively 92 specimens (46 horizontal and 46 vertical) of 46 patients diagnosed with AA incognito within 1 year. All specimens were assessed for 20 features, including hair counts and follicular ratios. The numbers were compared with 46 control specimens, consisting of 21 cases of TE and 25 cases of androgenetic alopecia.
The following main criteria are proposed: (a) preserved number of follicular units and decreased number of terminal follicles; (b) increased number of telogen structures (mean count of 37%) with presence of at least one telogen germinal unit or/and one small telogen follicle (c) decreased terminal:vellus ratio (mean ratio of 3.3 : 1) and (d) dilated infundibular openings.
Two histopathologic clues for AA incognito include the presence of dilated infundibular openings and small basaloid aggregates of cells with round, irregular or polygonal shape, lack of hair shaft and no apoptosis in the outer root sheath, corresponding to small telogen follicles.
隐匿性斑秃（AA）是斑秃的一种变体，其特征为急性弥漫性头发稀疏。皮肤镜检查显示黄色小点和短的再生毛发。与休止期脱发（TE）和雄激素性脱发进行鉴别诊断可能存在困难。
为了建立隐匿性斑秃诊断的组织病理学标准，我们回顾性评估了46例在1年内被诊断为隐匿性斑秃患者的92个标本（46个水平标本和46个垂直标本）。所有标本均评估了20项特征，包括毛发计数和毛囊比率。将这些数值与46个对照标本进行比较，对照标本包括21例休止期脱发和25例雄激素性脱发。
提出以下主要标准：（a）毛囊单位数量保留但终毛毛囊数量减少；（b）休止期结构数量增加（平均计数为37%），且存在至少一个休止期生发单位或/和一个小的休止期毛囊；（c）终毛与毳毛比率降低（平均比率为3.3:1）；（d）漏斗部开口扩大。
隐匿性斑秃的两个组织病理学线索包括漏斗部开口扩大以及存在圆形、不规则形或多边形的小基底样细胞聚集，缺乏毛干且外根鞘无凋亡，对应于小的休止期毛囊。
