An immunohistochemical characterization of basal cell carcinoma in patients below 40 years of age.

BACKGROUND

Basal cell carcinoma (BCC) is the most common form of skin cancer, mainly occurring in the elderly. Studies on BCC patients under the age of 40 (early-onset BCC) are scarce.

PATIENTS AND

METHODS

52 BCCs (48 patients, median age: 35 years) were investigated using immunohistochemistry, focusing on the cell cycle, immunogenicity, and HER2 expression. We used PCR to test for Human Papilloma Virus (HPV) and chromogenic in-situ hybridization for HER2 subclassification.

RESULTS

69% of cases were classified as non-aggressive subtypes, and 31% as aggressive. Changes in p16 and/or p53 were observed in 44% of cases. No HPV-DNA was detected. Overexpression of p16 was associated with an aggressive growth pattern, whereas p53 changes were independent of the growth pattern. Aggressive subtypes and p16-positivity correlated with higher expression levels of cyclin E1 and Ki-67, as well as a stronger B-cell response. Similar findings were observed in p53-altered basal cell carcinomas with respect to Ki-67 expression and B-lymphocyte infiltration; however, cyclin E1 expression was reduced in this subgroup. 71% of tumors belonged to the HER2-low group, which was associated with higher expression levels of cyclin E1 and Ki-67 and a more pronounced immunogenic response.

CONCLUSIONS

This is the largest immunohistochemical characterization of early-onset BCC to date. The classification into non-aggressive and aggressive subtypes appears appropriate, as applied in the elderly. Further sub-classification based on p16, p53, and HER2 may reflect disrupted cell cycle mechanisms combined with an immunogenic response.