The presentation of basal cell carcinoma (BCC), the most common human cancer, is an asymptomatic papule that often goes unnoticed by patients. The typical presentation is an enlarging papule or a sore that does not heal and bleeds easily—the so-called rodent ulcer (Fig. 36-1). The sun-exposed areas of the head and neck are the most common sites involved. A papule or plaque with a pearly or translucent appearance and crossed by telangiectasias is highly suggestive. Superficial BCCs resemble a patch of dermatitis with a pearly rim (Fig. 36-2). Sclerosing BCCs are insidious and hard to diagnose. They are white to yellow and often indistinguishable from common scar tissue (Fig. 36-3). Pigmented BCCs resemble nodular malignant melanoma (Fig. 36-4). Patients who received therapeutic radiation (in the 1950s and 1960s) for acne or tinea capitis are at high risk for the development of multiple BCCs.