Eccrine duct dilatation in neutrophilic scarring alopecias

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.

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.

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).

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.