Stromal CD10 expression, as well as increased dermal macrophages and decreased Langerhans cells, are associated with malignant transformation of keratinocytes

Background: It has become evident that resident stromal cells, such as fibroblasts and inflammatory cells, are involved in the metastatic process, including proliferation or migration of malignant neoplasms. We analyzed CD10+ stromal cells, dermal macrophages and Langerhans cells (LCs) in skin tumors. Methods: Immunohistological staining was performed with markers for macrophages (CD68), LC (CD1a), stromal fibroblasts (CD10) and cell proliferation (Ki67) in 12 normal skins (NSs) and 15 cases each of seborrheic keratosis (SK), actinic keratosis (AK), keratoacanthoma (KA), Bowen's disease (BD) and squamous cell carcinoma (SCC). Results: All SCCs showed weak to strong stromal CD10 expression, while all NS, SK and AK were negative. Weak CD10 expression was observed in only 2 of 15 samples in both BD and KA. The number of CD68+ cells and Ki67 labeling index in SCC and BD were significantly higher than that in KA, AK and SK. In contrast, the number of LC was lower in SCC and BD. The stromal CD10 expression was significantly correlated with the Ki67 labeling indices and CD68+ cells and negatively correlated with decreased LC. Conclusions: The stromal CD10 expression is associated with malignant transformation of keratinocytes together with infiltration of dermal macrophages and loss of LC.