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 immunohistochemical 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 positivity (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 expression 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.