Primary invasive melanoma on the head and neck: Distribution, ultraviolet exposure and histological subtype in 1,298 Australian patients

Abstract

8541 Background: The aim of this study was to determine the subsite distribution of invasive cutaneous melanoma of the head and neck and correlate this with the melanoma histologic type and ultraviolet exposure (UVE) at each particular subsite. Methods: This study comprised 1,298 patients seen at the Sydney Melanoma Unit (SMU) between 1990 and 2000. In each case, the histopathologic diagnosis of invasive melanoma was established by highly experienced SMU histopathologists. Histologic details, gender and patient age at diagnosis were available in all patients except in 5% in whom Breslow thickness could not be determined. Nine head and neck subsites were assigned: scalp, forehead, eyelids, nose, lips, chin, ears, face and neck. The relative tumour density (RTD) at each subsite was then examined in relation to gender and age of the patient and the relative UVE at this subsite. Relative UVE values as determined using polyusulphone UV dosimeters were used. Results: There was a direct correlation between high UVE and RTD at each subsite except the forehead (135 patients) and neck (335 patients), particularly in women, with the neck subsite prevailing in patients <50 years of age. Superficial spreading melanoma was the most common histologic type at all subsites except the lips (15 patients), nose (53 patients) and chin (15 patients), where desmoplastic melanoma predominated. Lentigo maligna melanoma was not more common on subsites having high UVE, nor was there an obvious association between melanoma thickness and UVE. Conclusions: The UVE was an important determinant of melanoma distribution on the head and neck. The lower RTDs at the forehead and neck subsites in women were possibly due to gender differences in hairstyles. Paradoxically, lentigo maligna melanoma, commonly considered to occur almost exclusively on sun-damaged skin, was not more common on areas of high UVE. No significant financial relationships to disclose.