Tubular carcinoma consists of an irregular proliferation of small glands and tubules lined by a single layer of cuboidal or columnar epithelium. The glands and tubules have angulated contours and widely open lumens. The neoplastic epithelium is homogenous and lacks significant atypia. Nucleoli are inconspicuous. Mitotic activity is not increased and necrosis is absent. Perineural invasion and lymphovascular invasion is rarely seen.