Eccrine squamous syringometaplasia. A prospective clinicopathologic study.

Squamous syringometaplasia (SS) is defined as a mature squamous metaplasia of the eccrine ducts. We prospectively evaluated its frequency and clinical and pathological features in a series of 21 patients. SS was found in association with several diseases, chiefly chronic ulcers. The patient' ages ranged between 20 and 80 years and there was no sex predominance. The involved eccrine ducts were usually located in the superficial and mid dermis and displayed inner keratinization. The stimulus required for SS is unknown. Differential diagnosis between SS and well-differentiated squamous cell carcinoma (SCC) depends on the preservation of a lobular configuration and the absence of epithelial dysplasia or invasion.