Despite occasional case reports, metastases from basal cell carcinomas (BCCs) are exceedingly rare; the morbidity and mortality they cause is generally the result of direct extension of the cancer into adjacent structures.1-5 If a BCC is left untreated or inadequately treated, this characteristic indolent growth pattern permits it to erode large areas of tissue before causing death. Thus, in the not-too-distant past, it was not uncommon for a BCC to destroy the whole side of the face, leaving the inside of the mouth visible through what had formerly been the cheek. Such lesions were called "rodent ulcers," because they looked as if a rat had gnawed a hole. Nonetheless, both the public and the medical profession had little awareness of the dangers of such lesions; therefore, they often went unrecognized or untreated for long periods of time and were usually presented for treatment at advanced stages.
June K. Robinson. What Are Adequate Treatment and Follow-up Care for Nonmelanoma Cutaneous Cancer?. Arch Dermatol. 1987;123(3):331–333. doi:10.1001/archderm.1987.01660270069016