S100A6 expression in cutaneous smooth muscle neoplasms

Abstract

The S100A6 protein is expressed in a variety of tissues and distinct staining patterns in S100A6 immunohistochemistry may be useful in the differential diagnosis of difficult lesions. We evaluated the staining pattern of the S100A6 antibody in 22 cases each of pilar leiomyoma (LM), angioleiomyoma (ALM), and cutaneous leiomyosarcoma (LMS). S100A6 labeled both the nucleus and cytoplasm of myocytes in positive cases. About 64% of LM and 86% ALM had positive staining to the S100A6 antibody but predominantly in a weak staining pattern. In contrast, 95% of the LMS exhibited moderate to strong staining with the S100A6 antibody. The difference in the frequency of positive cases was statistically significant in the LM vs LMS comparison (p = 0.025), but we found intensity of staining to be of greatest practical utility. Analysis between the groups taking in to consideration differences in intensity of staining using the nonparametric rank sum (Mann-Whitney U test) demonstrated that there was a statistically significant difference between LM and LMS and between ALM and LMS. Weak or absent S100A6 staining supports a diagnosis of LM, whereas strong positive staining supports a diagnosis of LMS.

The Role of S100A6 in Human Diseases: Molecular Mechanisms and Therapeutic Potential

“…As previously mentioned, the expression of S100A2, S100A3, and S100A6 in pilomatrixoma is conducive to determining the source of cells in abnormally differentiated tissues [87]. According to the unique immunohistochemical staining mode of S100A6 antibody in columnar leiomyoma (LM), angioleiomyoma (ALM), and skin leiomyoma (LMS), it is helpful for the differential diagnosis between them: weak or no S100A6 staining supports the diagnosis of LM, whereas strong positive staining supports the diagnosis of LMS [88]. In addition, some studies have shown that the expression of S100A6 is significantly related to the malignant transformation of epidermal tumors, and the joint expression of S100A6 and MMP9 is related to the development of SCC [89].…”

S100A6: molecular function and biomarker role

“…S100A6 was expressed in some skin smooth muscle tumors and the difference in staining intensity between LM and LMS was statistically significant. A strong S100A6 staining is conducive to the diagnosis of LMS, whereas negative staining supports the diagnosis of LM [ 89 ]. Moreover, S100A6 mRNA was significantly elevated in cholangiocarcinoma (CCA), while no significant increase was observed in hepatocellular carcinoma (HCC).…”