In basaloid squamous cell carcinoma, the tumor cells are arranged in tightly packed nests, lobules, or anastomosing trabeculae with peripheral palisading. The intervening stroma is hyaline or mucoid. The cells are small, uniform with hyperchromatic nuclei, granular chromatin, inconspicuous nucleoli, and scant cytoplasm. Mitotic activity is increased with 15-30 mitoses/HPF. Ki-67 proliferation index is 50-80%. Areas of comedonecrosis are frequent.