Primary squamous cell carcinoma of the breast is a rare clinical entity. Two large review series found only five cases out of a total of 8351 breast malignancies. This case report presents a patient with metaplastic, pseudoangiosarcomatous carcinoma or acantholytic variant of a squamous cell carcinoma of the breast. This diagnosis was based on the histological finding of highly atypical, acantholytic squamous cells. Because the tumor stained positive for keratin and negative for factor VIII, the diagnosis of angiosarcoma was ruled out. Although only scattered case reports have been published on this histological variant, these tumors tend to follow an aggressive course.