Patients with multiple naevi (moles) have probably had considerable sun or tanning bed exposure and should be examined for BCC.
Naevi are a risk factor for melanoma, and the number in an individual grows with increasing ultraviolet radiation. Investigators asked whether the number of nevi might also forecast a predisposition to basal cell carcinoma (BCC).
The researchers recorded the number of naevi on the forearms and hands of volunteers from Queensland, Australia, in 1986, and the number on the backs of the same individuals in 1992. The subjects were followed prospectively for the development of new BCCs from 1992 through 2007. A total of 1339 individuals were evaluated for the duration of the study or until they died. In all, 1202 histologically confirmed BCCs were diagnosed in 401 subjects. Patients with naevi on the forearms and hands were more likely to develop BCCs than those without naevi (odds ratio, 1.5; 95% confidence interval, 1.1–1.9). Interestingly, presence of naevi on the hands and forearms was associated with BCCs on the head and neck, but not on the trunk or limbs. There was no association between naevi on the back or naevi on both the forearms and the back and BCC.
Comment: Confronted with a patient with large numbers of naevi, we tend to focus on identifying lesions suspicious for melanoma, but these patients are likely to have had significant sun or tanning bed exposure, rendering them susceptible to other types of skin cancer as well. Thus, evaluations of patients with multiple naevi, especially on the forearms and hands, should also include examination for basal cell carcinomas.
— Craig A. Elmets, MD, Published in Journal Watch Dermatology October 19, 2012
English version of the above :
If you have a lot of moles (naevi), it is likely that you also had a lot of sun exposure; making you more prone to non-melanoma skin cancers (in addition to a higher risk of melanoma). The commonest type of non-melanoma skin cancer (or any skin cancer) is basal cell carcinoma (BCC). Therefore, if you have a lot of moles, you are also prone to have BCCs as well.
Dr Ken Ho