Dermatologist explains how to read pigmented spots and spot melanoma early
Dr Ngan Pui-yan explains the differences between common pigmented spots such as freckles, sunspots and moles, and outlines the ABCDE rule and other warning signs that may indicate melanoma or other skin cancers. The article advises when to see a dermatologist and describes the diagnostic process.
Pigmented spots are among the most common skin findings, according to Dr Ngan Pui-yan, a specialist in dermatology and venereology. Writing for The Standard, she explains how to distinguish between benign blemishes and potential signs of skin cancer.
Freckles are small, flat, light-brown or reddish-brown dots caused by localised increases in melanin. They are strongly genetic, appear early in life — especially in fair-skinned people — darken after sun exposure, and often fade in winter. Freckles themselves are entirely benign, Dr Ngan says. Sunspots, also known as solar lentigines or age spots, are larger, flat, sharply bordered tan-to-dark-brown patches that result from cumulative ultraviolet damage. They become more numerous with age and do not fade significantly seasonally. Pure solar lentigines are harmless, though the sun damage that creates them elevates overall skin-cancer risk.
Ordinary moles, or nevi, are usually round or oval, uniform in colour, and stable for years. Seborrheic keratoses, also known as barnacles, are waxy, stuck-on brown growths that also increase with age and are benign. Atypical moles may show mild irregularity and warrant closer watching. Melanoma and some pigmented basal-cell carcinomas can begin as or mimic ordinary spots, Dr Ngan warns.
To identify early warning signs of melanoma, Dr Ngan advises applying the ABCDE rule: asymmetry; border irregularity; colour variation; diameter larger than six millimetres or any progressive growth; and evolving size, shape, colour, or itching, bleeding, crusting. One lesion that looks distinctly different from all the others is equally important, she says. An outlier spot should always be evaluated, even if it does not meet every ABCDE criterion.
Dr Ngan recommends scheduling a visit to a dermatologist if any of the following warning signs are observed: symptomatic changes; non-healing sores; new spots in adulthood, specifically after age 30 or 40; textural changes and scaly lesions that cannot be managed with cosmetic topicals; and asymmetric spread.
A dermatologist first performs a comprehensive skin examination and medical history review, using specialised diagnostic tools — such as a dermoscopy or Wood’s lamp — to assess whether pigment sits in the superficial or deeper skin layers. If any spot appears atypical or displays suspicious signs, the dermatologist performs a skin biopsy for a definitive diagnosis. Spots confirmed to be malignant require complete surgical excision with pathological margin verification to ensure local disease clearance, whereas benign freckles and sunspots can be left alone or treated cosmetically alongside strict daily sun protection guidance, Dr Ngan says.
Regular self-checks plus professional evaluation of anything that changes keep that map safe, she concludes.
