Using Stratum Corneum Thickness and Configuration to Distinguish Lichenoid Dermatoses.

BACKGROUND: Clues in the stratum corneum (SC) can aide in histopathologic diagnosis of many conditions. OBJECTIVE: To determine if SC configuration and thickness could help differentiate the lichenoid dermatoses. METHODS: A retrospective study was performed. A total of 305 cases (55 lichenoid keratosis, 51 lichen planus, 7 hypertrophic lichen planus, 40 lichenoid drug eruption, 19 lichenoid graft-vs.-host disease, 14 hypertrophic lupus, 46 lichenoid actinic keratosis, 73 lentigo maligna) fulfilled the selection criteria. Cases were digitally scanned using the 40× (0.23 µm/pixel) mode of a Hamamatsu NanoZoomer 2.0-HT Slide Scanner (Hamamatsu Photonics, Hamamatsu City, Japan), allowing for the creation of virtual (digital) slides. SC thicknesses and configuration were assessed for each case. RESULTS: Mixed SC patterns were common in cases of lichenoid keratoses. Compact parakeratosis was the most common pattern in lichenoid drug eruption. Tiered parakeratosis was the most predominant pattern in cases of lichenoid graft versus host disease and lichenoid actinic keratosis. Hypertrophic lupus had the highest average SC thickness. LIMITATIONS: The sample size for cases of hypertrophic lupus and hypertrophic lichen planus was low. CONCLUSIONS: SC thickness and configuration can be utilized to help differentiate the lichenoid dermatoses.