Lymphatic drainage patterns from primary cutaneous tumours of the forehead: refining the recommendations for selective neck dissection.

Recommended selective neck dissections for primary cutaneous tumours on the head and neck are based largely on clinical recurrence data acquired prior to the era of lymphatic mapping and sentinel lymph node (SLN) biopsy. This study aimed to examine lymphatic drainage patterns from the forehead in order to provide evidence upon which to base recommendations regarding the extent of neck dissection. Data were collected prospectively from all patients undergoing lymphoscintigraphy following diagnosis of a primary cutaneous tumour on the forehead. The site of injection of radioisotope was documented using a co-ordinate-based mapping system. The forehead was divided into glabellar, supra-orbital and anterior temple zones. The location of all SLNs was recorded and drainage patterns were analysed. Between 1994 and 2006, 152 patients underwent lymphoscintigraphy for primary cutaneous tumours on the forehead. Drainage was to 3.0 SLNs in 2.1 lymph node fields (mean values). Drainage was to ipsilateral SLNs in 85% of cases. Between zones there were significant differences in drainage patterns and the frequency of bilateral drainage. From the glabellar zone, drainage was more frequently to a higher number of SLNs and SLN fields, and to level I nodes. The forehead can be divided into zones with patterns of lymphatic drainage that vary significantly in terms of number of SLNs, number of SLN sites, likelihood of drainage to contralateral SLNs and predictability of drainage pattern. Drainage to level 1 nodes from the anterior temple is rare, suggesting that it may be safe to exclude this level when performing a selective neck dissection for tumours in this zone.