Large basal cell carcinoma, light micrograph. Basal cell (trichoblastic) carcinomas are the most common cutaneous tumours, accounting for approximately 70% of all malignant diseases of the skin. They are slow-growing cancers that rarely metastasize. The tumour is composed of cords and large islands of basophilic cells. Inside the tumoral mass, there is necrotic material. The scale bar corresponds to 2 mm.