Miteva Mariya, Castillo David, Sabiq Samar
Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL.
Am J Dermatopathol. 2019 Jul;41(7):492-497. doi: 10.1097/DAD.0000000000001349.
Frontal fibrosing alopecia (FFA) is an irreversible scarring alopecia, and its incidence has reached epidemic size. Immune privilege collapse of the bulge and epithelial mesenchymal transition play a role in the pathogenesis. We have noted adipose tissue in the dermis in several specimens from FFA.
Our primary objective was to verify the presence of adipose tissue at the isthmus level in biopsies from FFA. Additional objectives included the presence of deep inflammation and position of the sweat coils.
Eighty-three histologic specimens of FFA diagnosed at the Dermatopathology Laboratory at the Department of Dermatology, University of Miami, within 3 years were evaluated retrospectively. All biopsies were bisected horizontally and assessed at several levels. Sixty biopsies from androgenetic alopecia served as controls. Statistical analysis was performed using the χ test. A P value of 0.05 or less was considered significant.
Sixty specimens met the inclusion criteria for optimal quality and classic diagnostic features. Seventy percent demonstrated fat tissue infiltration at the isthmus level as clusters of cells or small globules versus 23% of the controls. The fat infiltration in the arrector pili muscle (APM) was present in 55% versus 15% of the controls, and the sweat coils were positioned in the reticular dermis in 43% versus 1.7% of the controls. All results were statistically significant (P < 0.0001). When accounting for the simultaneous presence of any of these 3 variables, 30% of the FFA cases had triple positivity, 61.7% had double positivity, and 75% had at least 1 positive variable versus 0%, 15%, and 10%, respectively, of the controls.
New histologic findings in FFA involve the presence of adipose tissue in the dermis. We believe that the close interaction of the hair follicles and the APM with the adipose tissue may play a role in APM degeneration and in epithelial mesenchymal transition.
额部纤维性秃发（FFA）是一种不可逆的瘢痕性秃发，其发病率已达到流行程度。毛囊隆突部的免疫特权丧失和上皮-间质转化在其发病机制中起作用。我们在FFA的多个标本的真皮层中发现了脂肪组织。
我们的主要目的是在FFA活检标本的峡部水平验证脂肪组织的存在。其他目的包括深部炎症的存在和汗腺蟠管的位置。
回顾性评估迈阿密大学皮肤科皮肤病理学实验室在3年内诊断的83例FFA组织学标本。所有活检标本均水平切成两半并在多个层面进行评估。选取60例雄激素性秃发的活检标本作为对照。采用χ检验进行统计学分析。P值小于或等于0.05被认为具有统计学意义。
60个标本符合质量最佳和具有典型诊断特征的纳入标准。70%的标本在峡部水平显示有脂肪组织浸润，呈细胞簇或小球状，而对照组为23%。立毛肌（APM）中的脂肪浸润在FFA组为55%，对照组为15%；汗腺蟠管位于网状真皮层的在FFA组为43%，对照组为1.7%。所有结果均具有统计学意义（P < 0.0001）。当考虑这3个变量中任何一个同时存在时，30%的FFA病例为三联阳性，61.7%为双阳性，75%至少有1个阳性变量，而对照组分别为0%、15%和10%。
FFA新的组织学发现包括真皮层中存在脂肪组织。我们认为毛囊和APM与脂肪组织的密切相互作用可能在APM退变和上皮-间质转化中起作用。
