The Diagnostic Utility of Immunohistochemistry (IHC) in Basal Cell Carcinoma  (Code-T0351)

Introduction: Basal cell carcinoma (BCC) is the most common malignant neoplasm in 
humans, accounting for 75% of all skin cancer cases. While it is a slow-growing tumor with a 
low metastatic potential, it can cause significant local tissue destruction. The pigmented 
variant of BCC poses a diagnostic challenge due to its overlap with malignant melanoma and 
other pigmented lesions. Immunohistochemistry (IHC) serves as an ancillary tool to improve 
diagnostic accuracy in such cases. 
Aims and Objectives: This study aims to highlight the role of IHC in differentiating 
pigmented BCC from histologically similar entities and to aid in accurate diagnosis for 
appropriate clinical management. 
Methods: A 56-year-old female presented with a slow-growing, painless pigmented 
cutaneous lesion on the dorsum of the nose. Histopathological examination revealed basaloid 
tumor nests with peripheral palisading, clefting, and melanin pigment deposits. A differential 
diagnosis of BCC, Trichoblastoma, Malignant Matricial Carcinoma, and Melanoma was 
considered. IHC markers including CK5/6, p63, BCL2, CK20, EMA, CD10, HMB45, and 
Ki67 were used for confirmation. 
Results: The tumor showed positivity for CK5/6, p63, and focal BCL2, while being negative 
for CK20, EMA, and CD10. HMB45 stained dendritic melanocytes and melanophages, and 
the Ki67 proliferation index was 45-50%. Based on these findings, a final diagnosis of 
pigmented BCC was made. 
Conclusion: IHC is a valuable diagnostic tool in distinguishing pigmented BCC from other 
histologically overlapping tumors, ensuring precise diagnosis and optimal patient 
management. 
Keywords: Basal Cell Carcinoma, Pigmented BCC, Immunohistochemistry, Skin Cancer, 
Diagnostic Pathology, Tumor Markers.