Basal cell carcinoma superficial type is a basal cell carcinoma in situ

Background: Basal cell carcinoma (BCC) is the most common skin cancer with rising incidence. Skin cancers may present either as non-invasive or invasive malignancy. The terminology of carcinoma in situ is used when the tumor is either just limited to epidermis or not present as single cells or nests in the dermis. However, unlike the usual terminology, superficial BCC instead of BCC in situ is used for BCC that is limited to epidermis. Purpose: We aim to compare the histomorphology of superficial BCC to nodular and infiltrative BCCs using electron microscopy to identify the ultrastructural characteristics and validate the previously proposed terminology. Methods A total of three cases from three BCC types (superficial BCC, nodular BCC, and infiltrative BCC) diagnosed by dermatopathologists at our institute were selected for review. Paraffin block tissue from these cases was sent for electron microscopy studies. Results Electron microscopy demonstrates disruption of basal lamina in both nodular and infiltrative type of BCC, while it remains intact in BCC superficial type after extensive examination. Conclusion Our study demonstrates intact basal lamina in the BCC superficial type; therefore, like with other in situ skin cancers there is no invasion of the neoplasm into the dermis. Therefore, the older term superficial BCC should be appropriately replaced with the newer terminology BCC in situ.