Henrik F. Lorentzen
DOI: 10.2340/00015555-3568

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.

The usual patient with halo naevus is a child or adolescent with a few halo naevi. Occasionally, multiple and eruptive halo naevi may arise in an adult patient. The current recommendation for these patients is a full examination of the skin for melanoma. In this case series, patients were examined using positron emission tomography (PET) scanning, blood tests and capsular endoscopy. A malignancy (3 primary melanomas, 1 melanoma skin metastasis with unknown primary and 1 melanoma lung metastases, 2 papillary thyroid carcinomas and 1 neuroendocrine tumour of the lung) was found in half of the patients, which was more than 100 times higher than expected. If these findings can be substantiated in a controlled trial, clinical practice may be changed for adult patients who present multiple halo naevi in an eruptive pattern.