Basosquamous cell carcinoma (BSCC) is a variant of basal cell carcinoma (BCC) which shows the histopathologic characteristics of BCC and squamous cell carcinoma (SCC) with or without transition zone between them. In transition zone, basaloid cells have eosinophilic cytoplasm and variable keratinization and often lack peripheral palisading. Fibroblast-rich, collagenized stroma is also characteristic. In recent studies, it is considered BCC occurs first, followed by differentiation of basaloid cells derived from germinative progenitor epithelia into squamous cells. It is good to make a final diagnosis with a large specimen obtained by removing the tumor because of misdiagnosis with superficial biopsy. We report a case of a 50-year-old white man presented a skin colored nodule on the right side of the nose for three years. Histopathologic findings of skin biopsy from other hospital were consistent with BCC. The patient was treated with Mohs micrographic surgery and involvement of suspicious SCC was showed in a resection margin. Overlying epidermis permeating down into the dermis with atypical squamous cell, horn cysts and individual keratinization were observed. There were clefts around the tumor nests and palisading atypical basaloid cells. But, there was no metatypical cell showing intermediate characteristics of basaloid cells of BCC and spinous cells of SCC. Considering the above findings, a collision tumor (mixed BSCC) was diagnosed.