Eccrine Duct Dilatation in Neutrophilic Scarring Alopecias.

Background: Eccrine duct dilatation (EDD) has been noted to occur significantly more often in primary lymphocytic scarring alopecias compared with non-scarring alopecias, thus serving as a possible histopathologic marker for primary scarring alopecias with a lymphocytic infiltrate. This study aims to determine the presence and role of EDD in primary neutrophilic scarring alopecias. Methods: We performed a retrospective review comparing primary scarring alopecia (neutrophilic, n = 90; lymphocytic, n = 100) and non-scarring alopecia (n = 123) for presence of EDD, seen in Boston University School of Medicine between 2013 and 2017. Results: EDD was more commonly seen in primary neutrophilic scarring (62.2%, 56/90) and primary lymphocytic scarring alopecias (54.0%, 54/100) than in non-scarring alopecias (25.2%, 31/123) (P < 0.001). Albeit uncommon, non-scarring alopecias exhibited the biggest ratio of dilated eccrine duct lumen to background duct lumen (14.33), followed by lymphocytic (10.99) and neutrophilic scarring alopecias (6.66). Conclusion: EDD is seen more frequently in primary scarring alopecias compared with non-scarring alopecias and usually found in sections containing inflammation and dermal fibrosis, serving as a possible histopathologic clue for a scarring process. Non-scarring alopecias have significantly fewer but considerably larger EDD which, may imply a different pathologic cause.