Multiple primary melanoma: the impact of atypical naevi and follow up

Patients with melanoma are especially encouraged to have regular follow- up visits with their dermatologist and to perform total-body skin examination on a routine basis to identify new pigmented lesions or detect significant changes in existing naevi.

To identify main risk factors (sex, age, number of common and atypical naevi, family history, phototype) associated with multiple primary melanomas (MPM) and to investigate the association between regular follow up and tumour thickness of a second primary melanoma.

We performed a retrospective analysis of patients with MPM in order to evaluate risk factors for developing a second primary melanoma. Medical records of patients with melanoma who developed a second primary melanoma were selected from a database of all patients with histopathologically confirmed melanoma treated at the dermatology clinic of the University of Florence, Italy, from 2000 to 2004. Medical data culled from the patient records were as follows: medical history, number of typical naevi, presence of atypical naevi, Breslow thickness, Clark level and histotype of the melanomas, site of the melanomas and patient adherence to 6-month follow-up examinations.

The presence of atypical naevi was associated with a higher risk of developing MPM (adjusted odds ratio 3·28, 95% confidence interval 1·35–7·44). Moreover, in the subjects who did not attend follow up, we noted that the thickness of the second melanoma was significantly higher, with a mean thickness of 1·22 mm, in comparison with patients with a careful adherence to follow up in whom the mean thickness was 0·36 mm (P = 0·0189).

For the first time, the validity of this clinical approach has been supported by real comparison of thickness levels of second melanoma in patients with or without periodical follow up. Results obtained from this analysis show that follow up is an effective method for early detection of melanoma.