The sudden appearance of a new spot or the rapid change in an existing one causes significant anxiety, leading many to wonder if skin cancer can develop overnight. Skin cancer is the uncontrolled growth of abnormal skin cells, typically stemming from DNA damage often caused by ultraviolet radiation exposure. While a lesion may seem to appear suddenly, the underlying biological process is usually one of gradual, cumulative change. Understanding the variable growth patterns of different skin cancers is key to assessing the risk associated with a new or evolving spot.
The Typical Progression: Gradual Change Over Time
The vast majority of skin cancers, specifically Basal Cell Carcinoma (BCC) and Squamous Cell Carcinoma (SCC), follow a slow, progressive growth pattern. BCC, the most common type, is a slow-growing tumor, averaging around 0.7 millimeters per month along its longest axis. A noticeable lesion often takes many months or even years to fully develop.
SCC is also a common non-melanoma skin cancer that is usually slow to progress, though it can spread if left untreated. What feels like a sudden appearance is often a lesion that was simply unnoticed during its smaller, earlier stages. Routine skin surveillance is important due to this slow growth.
Even standard Melanoma, the most serious form of skin cancer, often arises from a pre-existing mole or lesion that undergoes incremental changes over an extended period. This slow evolution is the basis for the “ABCDE” mnemonic, where “E” stands for Evolving—a change in size, shape, or color tracked over months to years.
Understanding Rapidly Growing Skin Cancers
While most skin cancers develop gradually, aggressive subtypes can present with a fast growth rate. Nodular Melanoma (NM) is one exception, characterized by early vertical growth rather than the initial horizontal spread seen in other melanomas. This vertical growth allows the tumor to gain depth quickly, which is a significant factor in prognosis.
Nodular Melanoma may not adhere to the traditional ABCDE criteria, often presenting instead as a new, raised, and symmetrical bump. Instead, it is frequently identified using the EFG criteria: Elevated, Firm to the touch, and Growing progressively, with changes sometimes noted over a matter of weeks. This rapid nature means that any lesion that is quickly becoming raised or firm warrants immediate medical attention.
Even more rare is Merkel Cell Carcinoma (MCC), known for its fast growth and tendency to spread early. MCC usually appears as a firm, painless, dome-shaped lump on sun-exposed skin, often described as red or violet. The rapid speed at which MCC tumors enlarge is often the feature that first prompts medical attention.
How to Monitor for Sudden and Concerning Changes
Given the possibility of rapidly growing lesions, establishing a consistent monitoring routine is the best defense against delayed detection. Performing a full-body self-examination at least once a month helps establish a baseline for your skin, allowing you to easily identify any new or changing spots. This self-check should involve scanning for both existing moles that are evolving and for any new lesions that appear.
When performing a self-examination, look for the standard features of Asymmetry, Border irregularity, multiple Colors, and a Diameter larger than 6 millimeters. Critically, focus on the “Evolution” of any spot, meaning any change in size, shape, or color over a short period. A spot that changes noticeably in a matter of weeks, or a new lump that feels firm and is rapidly elevating, should raise suspicion.
Any lesion that bleeds easily, oozes, or develops a crust and does not heal within a few weeks requires a professional evaluation. Beyond self-monitoring, scheduling an annual professional skin check allows a dermatologist to examine hard-to-see areas and use specialized tools to detect subtle changes. These specialists are trained to spot the early, often minor, indications of both slow- and fast-growing skin cancers.