Immunoexpression of Bmi-1, CK15, Bcl-2 in different types of basal cell carcinomas

Introduction: Basal cell carcinoma (BCC) occurs in aggressive and non-aggressive forms. The expression of immu-nohistochemical markers varies in different types of BCC. Aim: Immunohistochemical analysis of selected proteins in BCCs. Material and methods: The immunohistochemical method was used to examine the immunoexpression of Bmi-1, CK15 and Bcl-2 in 56 cases of BCC divided into four groups. Results: Positive Bmi-1 staining 3-4+ level (nodular type) was seen in 91.3% of samples, 4+ (infiltrative) in 92.3%, 4+ (nodular/infiltrative) - 69.2%, 3+ - 30.8%, in BSC 3+ - 42.8%, and 28.6% each for 2+ and 4+. Low grade positiv- ity (0-1+) in CK15 staining was present in 52.1% of nodular BCC, 46.2% - nodular/infiltrative, 92.3% - infiltrative, and 100% - BSC, but levels 2-3+ in nodular BCC in 47.8%, nodular/infiltrative BCC - 53.8%, infiltrative - 7.7%. Bcl-2 positivity (3-4+) was revealed in nodular BCC in 95.6%, (1-2+) in 100% of BSC, infiltrative and infiltrative/nodular BCC, but the lowest (0-1+) in 76.9% of nodular/infiltrative BCC, 71.4% of BSC, and in 38.4% of infiltrative BCC. Conclusions: Positive Bmi-1 staining was the highest in the aggressive infiltrative subtype of BCCs, whereas the lowest in basosquamous cell carcinomas (BSC). Infiltrative BCC was characterized by a lower level of CK15 expres- sion than nodular BCC and nodular/infiltrative BCC. Differentiation of Bcl-2 expression depended on the type of tumour; the highest level was found in nodular BCC, low grade in nodular/infiltrative and infiltrative BCCs, and BSC.