Inherent variation of the disease process can be due to the severity of the disease.
Basal cell carcinoma, the most common skin cancer, has a number of subtypes that present along a spectrum of severity. Early, small basal cell carcinomas can look like a blemish or a tiny pimple. Advanced basal cell carcinomas can appear as an ulcerating tumor.
Basal cell carcinoma
This early, small papule of basal cell carcinoma has some tiny telangiectasias suggesting the diagnosis
Basal cell carcinomas progress over time from subtle to more obvious skin lesions
This is a quite large nodular basal cell carcinoma with a classic "rolled" border
This long-standing basal cell carcinoma has developed a bloody crust over a skin ulcer caused by the tumor