Characterization of the inflammatory features of central centrifugal cicatricial alopecia

Abstract

Central centrifugal cicatricial alopecia (CCCA) is a scarring alopecia that primarily affects women of African descent. Although histopathological features of CCCA have been described, the pathophysiology of this disease remains unclear. To better understand the components of CCCA pathophysiology, we evaluated the composition of the inflammatory infiltrate, the distribution of Langerhans cells (LCs), and the relationship between fibrosis and perifollicular vessel distribution. Our data indicate that CCCA is associated with a CD4-predominant T-cell infiltrate with increased LCs extending into the lower hair follicle. Fibroplasia associated with follicular scarring displaces blood vessels away from the outer root sheath epithelium. These data indicate that CCCA is an inflammatory scarring alopecia with unique pathophysiologic features that differentiate it from other lymphocytic scarring processes.

Keywords: CD4 T-cells; Langerhans cells; central centrifugal; cicatricial alopecia; scarring alopecia.

Figure 1.. CD4:CD8 T-cell ratios in follicles of CCCA:

Both affected (blue dots) and unaffected (red dots) follicles showed an elevated CD4:CD8 T-cell ratio (A). The elevated CD4:CD8 ratio was seen in both the perifollicular (B) and intrafollicular (C) infiltrates of these follicles. A representative affected follicle is shown on H&E (D), as well as CD3 (E), and CD8 (F) immunostaining, also demonstrating a CD4 T-cell predominance. This is also seen in a representative unaffected follicle (G: H&E, H: CD3, I: CD8). Photomicrographs 100x, D and G-H&E, E, F, H and I-hematoxylin.

Figure 2:. CD1a+ Cells Associated with Affected Follicles:

Affected and unaffected follicles were evaluated for the number of CD1a+ cells in the outer root sheath. Affected follicles have a higher number of CD1a+ cells than unaffected follicles (A). CD1a immunostaining of representative affected and unaffected follicle is seen in panels B and C, respectively. Photomicrographs 200x, B and C-hematoxylin.

Figure 3.. Average Blood Vessel Cluster Distance from Affected and Unaffected Follicles:

Blood vessel clusters were on average further away from the outer root sheath in affected follicles than unaffected follicles (A). CD31+ immunostaining of a respective affected (B) and unaffected follicle (C) demonstrate the visibly appreciable difference in blood vessel cluster distance. Photomicrographs 100x, B and C-hematoxylin.

Figure 4.. CD31 staining in follicles with Mucinous Fibroplasia:

Affected follicles showing mucinous fibroplasia (A) demonstrated an increased number of single vessels and solitary scattered CD31+ cells (B). Photomicrographs 100x, A-H&E and B-hematoxylin.

Figure 5.. Pictoral representation of changes in blood vessels surrounding CCCA follicles.

Unaffected follicles demonstrate a normal density of blood vessels clustered both close to and further from the follicle (A). As the follicle shows changes of mucinous fibroplasia, an increased number of single vessels and scattered solitary endothelial cells are seen (B). Once the follicle is fully affected and demonstrates fibrosis, only more distantly located blood vessel clusters remain (C).