Eccrine Squamous Syringometaplasia Associated With Lichen Sclerosus et Atrophicus.

Eccrine squamous syringometaplasia (ESS) has been associated with several conditions including morphea, linear scleroderma, and burns. It is yet to be reported in lichen sclerosus et atrophicus (LSA). We describe a bullous LSA plaque on the forearm of a woman with pre-existing genital LSA and vitiligo. Besides the histopathological findings of bullous LSA, numerous small irregular squamoid structures were present in the mid and upper dermis always above the normal eccrine glands. The histopathology, periodic acid-Schiff stain, and positive immunostains for P63, low molecular weight keratins 8&18, epithelial membrane antigen, and carcinoembryonic antigen supported the diagnosis of ESS. The pathogenesis of ESS in LSA may be related to ischemia, inflammation, and fibrosis.