Many moles on the body - how many pieces is that?

In this article, we will tell you in detail at what number of moles it is necessary to be regularly observed by a dermatologist.
What is a mole and which moles matter?

Let's start by moving away from the usual "mole" to the medical term "nevus". What is nevus? Not every brown formation on the skin fits the definition of a "mole" and will be counted.

In 1990, the IARC clearly defined the concept of "moles" (pigmented nevus) for epidemiological studies of this type.

Nevus are brown or black pigment spots or nodules (papules) that stand out quite well in a darker color against the background of the surrounding skin. The formations to be counted should not have signs of freckles, solar lentigo, seborrheic keratosis, coffee-colored spots with milk or other non-melanocytic lesions.

The conclusions from this definition are both pleasant and not very:

1) What you previously thought was a mole may not turn out to be one, and your risk of melanoma will be lower than thought.

2) You will not be able to independently calculate the number of nevi on the skin. Only a dermatologist or dermatologist will do this. Let's say more, in some cases, without a dermatoscope, even an experienced specialist will not always be able to distinguish a solar lentigo from a pigmented nevus.

Atypical (dysplastic) nevi

According to the same IARC definition, atypical nevi are subject to separate counting:

In order for the nevus to be recognized as atypical, at least part of the nevus must be represented as a spot, in addition to this, at least 3 of the following criteria must be present:

  • fuzzy boundary;
  • size 5 mm or more;
  • different colors in coloring;
  • uneven contour;
  • redness of the skin.
How many moles are there? And which ones?

Here are the 2 largest ones that we managed to find. Both papers are meta-analyses, i.e. generalizations of data from several clinical trials.

1. A study of Italian authors: Meta-analysis of risk factors for cutaneous melanoma: I. Common and atypical nevi.

The results of 46 separate studies are summarized.
All the same, but in words: the risk of melanoma increases in direct proportion to the number of nevi, both normal and atypical. The minimum risk of getting melanoma is in a person with 15 or less nevi on the skin, the absence of nevi on the hands and the absence of atypical nevi.

The maximum risk is in a person with more than 100 normal nevi, 15 nevi on his hands and 5 atypical nevi.

2. American study: Catherine M. Olsen, Heidi J. Carroll and David C. Whiteman. Estimating the Attributable Fraction for Cancer: A Meta-analysis of Nevi and Melanoma

The results of 49 studies are summarized.
The results are consistent with the results of the previous study.

The risk of melanoma increases along with the number of normal and/or atypical nevi on the skin.

In contrast to the previous study, it is noted that 42% of patients with melanoma had 25 or more common nevi and/or 1 atypical nevus or more.

It is these patients that the authors refer to the high-risk group and recommend them to be more closely monitored and trained in self-diagnosis methods.

Unfortunately, neither in the first nor in the second studies, the authors do not give specific recommendations on the frequency and format of observation of patients at risk. We will try to formulate answers to these questions later.
If a lot of moles are bad, then they need to be removed?

Fortunately, no.

In a large percentage of cases, melanoma can develop against the background of unchanged skin. From this point of view, the removal of ordinary pigment nevi in order to prevent melanoma is meaningless. On the other hand, it is important to note here that if one or another nevus arouses suspicion in an oncologist, then its removal (for diagnostic purposes) is quite indicated.

Does a large number of moles increase the risk of basal cell carcinoma and squamous cell carcinoma?

No. Basal cell, squamous cell skin cancer and melanoma originate from various skin cells. A large number of moles (pigmented nevi) does not increase the risk of getting basal cell carcinoma or squamous cell carcinoma.

What to do if there are a lot of moles on the body?

From the first study, we found out that the probability of getting melanoma increases in direct proportion to the number of common and / or dysplastic (atypical) nevi.

The second meta-analysis states that people with 25 or more common nevi and/or 1 or more atypical nevi are at risk for developing melanoma.

We think that after reading the previous paragraph, all readers most likely divided into 3 groups:

  • "I have a bunch of moles and definitely more than 25, I will get melanoma! Oh, horror!"
  • "I have less than 25 moles, and now I can relax 100% on the topic of melanoma."
  • They ran to count the moles and realized that they could not cope without a doctor.

Unfortunately, everyone can get melanoma. And those who have more than 25 moles, and those who have less, and even those who have only one or two moles. No one is 100% insured, just the probability is different for everyone. It is important to understand that the number of moles is just one of the 17 risk factors for melanoma. Therefore, it is not worth making any fatal conclusions and panicking just because you have a lot of moles.

Summary, or Briefly about the main thing:

A large number of moles – 25, 50 or 100 – is not a reason to panic, but just one of the 17 risk factors for melanoma. In such a situation, it is worth seeing an oncologist with dermatoscopy at least once every six months or more often, if your doctor thinks so. Self-examination of the entire skin should be carried out 1 time a month.

According to research, the best way to observe a large number of moles is digital mapping of nevi.
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List of literature

1) Kurtis B. Reed, Jerry D. Brewer, Christine M. Lohse, Kariline E. Bringe, Crystal N. Pruitt, and Lawrence E. Gibson. Increasing Incidence of Melanoma Among Young Adults: An Epidemiological Study in Olmsted County, Minnesota.

2) Gandini S, Sera F, Cattaruzza MS, et al. Meta–analysis of risk factors for cutaneous melanoma: I. Common and atypical naevi. Eur J Cancer. 2005; 41:28–44. [PubMed: 15617989]

3) Olsen CM, Carroll HJ, Whiteman DC. Estimating the attributable fraction for cancer: A metaanalysis of nevi and melanoma. Cancer Prev Res (Phila). 2010; 3:233–245. [PubMed: 20086181]

4) Mitra D1, Luo X, Morgan A, Wang J, Hoang MP, Lo J, Guerrero CR, Lennerz JK, Mihm MC, Wargo JA, Robinson KC, Devi SP, Vanover JC, D'Orazio JA, McMahon M, Bosenberg MW, Haigis KM, Haber DA, Wang Y, Fisher DE. An ultraviolet–radiation–independent pathway to melanoma carcinogenesis in the red hair/fair skin background. Nature. 2012 Nov 15;491(7424):449–53. doi: 10.1038/nature11624. Epub 2012 Oct 31.

5) Wu S, Han J, Laden F, Qureshi AA. Long–term ultraviolet flux, other potential risk factors, and skin cancer risk: a cohort study Cancer Epidemiol Biomarkers Prev. 2014 Jun;23(6):1080–9. doi: 10.1158/1055–9965.EPI–13–0821.

6) Wheless L, Black J, Alberg AJ. Nonmelanoma skin cancer and the risk of second primary cancers: a systematic review. Cancer Epidemiol Biomarkers Prev. 2010 Jul;19(7):1686–95. doi: 10.1158/1055–9965.EPI–10–0243. Epub 2010 Jun 22.

7) Vajdic CM, Chong AH, Kelly PJ, Meagher NS, Van Leeuwen MT, Grulich AE, Webster AC.

Survival after cutaneous melanoma in kidney transplant recipients: a population–based matched cohort study. Am J Transplant. 2014 Jun;14(6):1368–75. doi: 10.1111/ajt.12716. Epub 2014 Apr 14.

8) Risk of melanoma in people with HIV/AIDS in the pre– and post–HAART eras: a systematic review and meta–analysis of cohort studies. Olsen CM, Knight LL, Green AC. PLoS One. 2014 Apr 16;9(4):e95096. doi: 10.1371/journal.pone.0095096. eCollection 2014. Review.

9) Kraemer KH, Lee MM, Scotto J. Xeroderma pigmentosum. Cutaneous, ocular, and neurologic abnormalities in 830 published cases. Arch Dermatol. 1987 Feb;123(2):241–50.

10) Udayakumar D, Tsao H. Melanoma genetics: an update on risk–associated genes. Hematol Oncol Clin North Am. 2009; 23:415–429. vii. [PubMed: 19464594] Authors review genes of variable risk implicated in CMM, most notably CDKN2A.

11) Pappo AS, Armstrong GT, Liu W, et al. Melanoma as a subsequent neoplasm in adult survivors of childhood cancer: A report from the childhood cancer survivor study. Pediatr Blood Cancer. 2012

12) Indoor tanning and risk of melanoma: a case–control study in a highly exposed population.

Lazovich D1, Vogel RI, Berwick M, Weinstock MA, Anderson KE, Warshaw EM. Cancer Epidemiol Biomarkers Prev. 2010 Jun;19(6):1557–68. doi: 10.1158/1055–9965.EPI–09–1249. Epub 2010 May 26.