Eruptive Halo Naevi: A Possible Indicator of Malignant Disease in a Case Series of Post-Adolescent Patients.

Halo naevi are considered benign. They occur in children and adolescents. Eruptive multiple halo naevi are infrequently seen in adults. The first patient in this case series had previously had melanoma. Positron emission tomography-computed tomography (PET-CT) showed a papillary thyroid carcinoma. Subsequent adult patients underwent an examination programme similar to melanoma patients with unknown primary, including PET scanning. Sixteen patients were followed over a 6-year period. In total there were 2 papillary thyroid cancers, 1 neuroendocrine lung tumour, 1 patient had had lung metastases from a thin melanoma 7 years previously, 3 patients had primary cutaneous melanoma (1 had had halo naevi since excision of 2 melanomas 15 years previously) and 1 had melanoma metastasis with unknown primary. The incidence of melanoma was 955 times higher than expected (standardized incidence rate). The benefits of PET scanning must be validated in a controlled trial prior to implementation into clinical practice.