Figure 2. Positive PTCH staining in central polyhedral and loosely connected angular cells of ameloblastoma (A) and mesenchymal cells of odontogenic myxoma (B). Fragment of normal oral mucosa shows weak immuno-positivity in the epithelium (C). While the epidermis overlying the basal cell carcinoma presented a strong PTCH staining, the vast majority of neoplastic cells were negative for PTCH (D).