The oldest new finding in atopic dermatitis: subclinical miliaria as an origin.

IMPORTANCE In 1947, Sulzberger and colleagues published a micrograph of a blocked acrosyringium in a patient with atopic dermatitis (AD), believing that it had a large role in the disease process. Lacking appropriate probes, they could not confirm the finding. OBJECTIVE To confirm the observations by Sulzberger et al on the blockage of sweat ducts in AD in pathologic specimens. DESIGN AND SETTING Biopsy specimens diagnostic of various inflammatory diseases and with a secondary differential diagnosis of eczema were evaluated at an academic medical center. EXPOSURES Evidence of ductal obstruction in each specimen was examined following staining with hematoxylin-eosin, periodic acid-Schiff, and Gram stain. MAIN OUTCOMES AND MEASURES Comparison of biopsy specimens with control specimens and additional controls consisting of noninflamed skin. RESULTS Using 36 biopsy specimens, this study confirmed the observations by Sulzberger et al on the blockage of sweat ducts in AD. Blocked acrosyringia were noted in each specimen on routine staining with hematoxylin-eosin. The study also confirmed the findings by earlier investigators about the blockage of sweat ducts in miliaria, showing eosinophilic material in the ducts that was positive for periodic acid-Schiff. Previous researchers also observed bacteria in the blockages, and this study demonstrated the same findings in AD, rather than miliaria. CONCLUSION AND RELEVANCE Subclinical miliaria may be the earliest change in AD and likely initiates the process that causes intense pruritus.