SC may be classified as well, moderately, or poorly differentiated. The most common presentation is characterized by irregular lobules and sheets with distinctive invasiveness containing cells whose cytoplasm is pale, foamy, and multivacuolated (Figs. 14.4 and 14.5). Some atypical eosinophilic-keratinizing cells with keratin pearls, as seen in squamous cell carcinoma, are found in larger lobules (Fig. 14.6). SC commonly shows considerable nuclear and nucleolar pleomorphism, abnormal mitoses, and zones of central necrosis. In the poorly differentiate variant, basaloid cells are predominant with only a small minority of recognizable sebocytes (Fig. 14.7). Regardless of grade, intraepithelial pagetoid spread and/or multicentric pattern are often seen.