• Ivan Bristow

The mystery of moles

Virtually everyone will have moles somewhere on their skin but I once heard the phrase “We are rarely born with moles and we rarely die with them”. This is derived from the general observation that mole counts at birth and in old age are generally lower than in our middle years so what is happening with them?





In 1985, Prof Rona Mackie and colleagues published a study [1] of 432 healthy white individuals aged between 4 days and 96 years of age to study the frequency and distribution of moles. The work showed that mole numbers in the first decade were low (averaging 2-3 lesions) but steadily increasing to a peak in the 20 to 29-year-old age group (the mean number being 27 moles) and then showing a gradual decline in frequency to an average of 6 lesions in the over 70’s age groups. Thus, demonstrating a trend of most lesions appearing in the first two decades of life with a gradual decline in numbers in middle to old age. Apart from a study a few years afterwards [2], this area of study remained unexplored for many years, but a study published this year [3] attempted to repeat the exercise, including a broad range of skin types.


The Italian study enrolled 900 patients from a broad age range, with a median age of 46 years. A total of 18 136 naevi were discovered. The results were broadly similar, confirming the earlier UK study, that mole numbers showed a significant increase in the first two decades of life but drastically decreased after the age of 50. The study cohort contained a broader range of skin colour from type 1 to type 5 with the predominant groups being skin types 2 and 3 in this study. A sub-analysis demonstrated there was a similar pattern across all the different skin types. The peak mole count was found in adults in their 30’s (median numbers 25-30 moles), dropping in the patients aged 51-60 to a median of 10, onto a median of 0 in patients over 80.


Does this all matter?


What these studies have confirmed is the natural process of naevi development and regression. For healthcare professionals, this data helps in our skin assessment, particularly with regard to melanoma. High levels of sun exposure, particularly as a child, can lead to higher final mole counts [4] and is a significant risk factor for melanoma development [5]. In an earlier blog, I discussed how mole counting on the feet and limbs can quickly identify such patients (click here to read the full article).


It is also important to remember that melanoma can occur at any age (although they are rare before puberty) but most often they are seen in the over-fifty age group. This latest study suggests that older adults (those beyond 40), are less likely to be developing any new moles. Consequently, when looking at these patients, one should be wary of any new “moles”. Such lesions should be carefully assessed both clinically and dermatoscopically, and where there is doubt, be referred for a second opinion.



References


1. Mackie RM, English J, Aitchison TC, Fitzsimons CP, Wilson P: The number and distribution of benign pigmented moles (melanocytic naevi) in a healthy British population. Br J Dermatol 1985, 113(2):167-174.

2. Colonna S, Zina G: [Acquired melanocytic nevus. Epidemiologic clinical study of a healthy population]. G Ital Dermatol Venereol 1990, 125(6):231-236.

3. Di Brizzi EV, Pampena R, Licata G, Calabrese G, Longo C, Argenziano G: Are we born and do we die without nevi? A cross-sectional study. Int J Dermatol 2021, 60(11):1405-1410.

4. Bauer J, Buttner P, Wiecker TS, Luther H, Garbe C: Risk factors of incident melanocytic nevi: a longitudinal study in a cohort of 1,232 young German children. Int J Cancer 2005, 115(1):121-126.

5. Gandini S, Sera F, Cattaruzza MS, Pasquini P, Abeni D, Boyle P, Melchi CF: Meta-analysis of risk factors for cutaneous melanoma: I. Common and atypical naevi. Eur J Cancer 2005, 41(1):28-44.

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