Tubular carcinoma is usually a stellate or an irregular lesion with infiltrating borders. There is an irregular proliferation of small glands and tubules lined by a single layer of cuboidal or columnar epithelium. At least 90% or more of the lesion should have this architecture to be classified as tubular carcinoma. If less than 90% of the lesion has tubular architecture, it may be called invasive ductal carcinoma with tubular features. The prognosis in such cases is not as favorable as that seen with pure tubular carcicnoma.