Utility of GLI1 RNA Chromogenic In Situ Hybridization in Distinguishing Basal Cell Carcinoma From Histopathologic Mimics

The study investigates the effectiveness of GLI1 RNA chromogenic in situ hybridization (CISH) in distinguishing basal cell carcinoma (BCC) from other epithelial neoplasms, involving 220 cases, including 60 BCCs. It found that GLI1 RNA CISH is highly sensitive (95%) and specific (98%) for identifying BCCs, with positive GLI1 expression in 57 out of 60 BCC cases. However, it is less specific when differentiating BCC from benign follicular tumors. The method shows promise for precise classification of challenging basaloid tumors, especially in small biopsy specimens or cases with metaplastic differentiation or metastatic disease, but faces limitations such as higher costs and longer processing times compared to immunohistochemistry (IHC).