Hypertrophic lupus erythematosus: the diagnostic utility of CD123 staining.

CD123-positive plasmacytoid dendrocytes are prominent in the infiltrate of discoid lupus erythematosus (LE). We hypothesized that these cells would also be present in hypertrophic LE and would aid in the histopathologic distinction from squamous cell carcinoma (SCC) and hypertrophic actinic keratosis (AK). Five cases of hypertrophic LE and 10 cases each of SCC and hypertrophic AK were stained with CD123. A heavy band of CD123-positive cells was present at the epidermal-dermal junction in all cases of hypertrophic LE, and only single or rare scattered clusters of CD123-positive cells were seen in SCC and actinic keratoses. The pattern of CD123 staining can be a useful feature to distinguish hypertrophic LE from SCC and hypertrophic AK.