The Unpredictability of Lymphatic Drainage from the Ear in Melanoma Patients, and Its Implications for Management
Annals of Surgical Oncology, 04/11/2013Peach HS et al.
The ear is known to have variable lymphatic drainage. The purpose of this study was to define better the lymphatic drainage patterns of the ear by correlating the location of primary tumors, classified according to the embryologically derived anatomical subunits of the ear, with their mapped sentinel nodes (SNs) identified by lymphoscintigraphy (LS). Lymphatic drainage of the ear has no predictable pattern and can be to SNs anywhere in the ipsilateral neck. Most commonly drainage is to cervical level II and the preauricular and postauricular LN fields. LS defines the lymphatic drainage pattern in individual melanoma patients and is essential for accurate SN identification and reliable SN biopsy.
Howard Peach (04/15/2013)
There is a significant degree of variability in the patterns of lymphatic drainage within the head and neck region. We considered whether it was possible to predict drainage from a specific anatomical site by correlating it with the embryological development of that site. We analysed our results from a defined region - the ear - using 'X - Y' co-ordinates, recorded at the the time of technetium injection for the sentinel node lymphoscintigraphy, to separate all cases of melanoma of the ear by their embryological subunit of origin. The lymphatic patterns of drainage from each of these embryological subunits were then analysed.
We found retrograde, antegrade and transaural patterns of drainage. Specifically 29% of all conchal primaries drained to post-auricular nodes, which together with drainage from the helical rim and lobule accounted for 26% of all nodes retrieved. Post-auricular together with level CII and pre-auricular were the lymph node basins most frequently identified on lymphoscintigraphy.
Our paper confirms that even with accurate primary localisation and corresponding lymphoscintigraphy, lymphatic drainage of the ear is highly variable. This degree of variability is likely to be replicated in other less easily defined anatomical areas of the head and neck. The small numbers in some of the embryological subunits prevent us from making specific recommendations regarding the extent of neck dissection. However our study high-lights those unexpected regions of drainage that could be considered for inclusion in a lymph node dissection, particularly for macroscopic SN disease, rather than those that should be excluded.
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