Immunohistochemical expression of cytokeratin 15, cytokeratin 19, follistatin, and Bmi-1 in basal cell carcinoma.

BACKGROUNDS: Basal cell carcinoma (BCC) is the most common cutaneous neoplasm. Despite numerous previous studies, the origin of BCC is still controversial.

OBJECTIVE: The aim of this study is to evaluate whether BCC arises from the hair follicle rather than the epidermal basal cell.

METHODS: The labeling index and differences of expression of the immunohistochemical (IHC) stainings of CK15, CK19, follistatin, and Bmi-1 were evaluated in 20 cases of BCC, 13 cases of trichoblastoma, 21 cases of actinic keratosis (AK), and 19 cases of squamous cell carcinoma (SCC) which were biopsied in the department of dermatology of the Yeungnam University Medical Center.

RESULTS: For CK15, labeling indexes of BCC (83.0%) and trichoblastoma (84.4%) were significantly higher than those of AK (15.9%) and SCC (15.8%). For CK19, labeling indexes of BCC (8.1%), trichoblastoma (6.6%), AK (3.5%), and SCC (14.8%) revealed no difference. For follistatin, labeling indexes of BCC (51.1%) and trichoblastoma (70.1%) were significantly higher than those of AK (0.9%) and SCC (8.5%). For Bmi-1, labeling indexes of BCC (74.4%) and trichoblastoma (84.7%) were significantly higher than those of AK (24.7%) and SCC (18.6%).

CONCLUSION: In this study, strong positivity of CK15, follistatin, and Bmi-1 was more frequently observed in BCC and trichoblastoma than in SCC and AK. These findings suggest that BCC and trichoblastoma share the same differentiation toward the hair follicle. Furthermore, CK15, follistatin, and Bmi-1 can be useful as markers to differentiate BCC from SCC.