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Value of sentinel node status as a prognostic factor in melanoma: prospective observational study

BMJ 2006; 332 doi: (Published 15 June 2006) Cite this as: BMJ 2006;332:1423

Value of sentinel node status as a prognostic factor in melanoma: prospective observational study

EDITOR - In the published paper by Kettlewell et al, it was
interesting to note that the sentinel lymph node biopsies were performed
within eight weeks of the wide local excision of the malignant melanoma
scar. This contrasts with the techniques used in units as our own, where
the wide local excision is undertaken at the same time as the sentinel
lymph node biopsy. The theory is that each area of skin drains to a
‘sentinel’ -first draining node. In sentinel lymph node mapping, the first
draining node is identified by a double contrast method with a pre-operative lymphoscintigraphy with the injection of Tc99m-labelled albumin
nanocolloids and per-operative injection of patent blue dye. Both are
taken up by the local lymphatic vessels around the excisional biopsy scar
and carried to the sentinel node. The sentinel node is then identified pre
-operatively by performing a lyphoscintogram, and intra-operatively with
the use of a gamma probe and visually by the presence of the blue dye
within a lymph node. The wide local excision is typically performed in the
operation after the sentinel lymph node biopsy. The thought being that
performing a wide local excision first, would give rise to inaccuracies in
the sentinel lymph node mapping in two ways: Firstly, the surgery may
distort local lymphatic drainage patterns. Secondly, margins for wide
local excision after a diagnostic excisional biopsy can be 1cm or 2 cm
depending on the Breslow thickness of the primary lesion. The excisional
defects can be rather large meaning that skin adjacent to site of the wide
local excision, may theoretically have discordant drainage patterns to
that of the primary lesion (or excisional biopsy scar). If this is the
case then may a proportion of patients with negative sentinel lymph node
biopsies who eventually died of melanoma or experience recurrence may had
false negative results? It would be interesting to know the relative
number of patients having concordant sentinel lymph node mapping and wide
local excision as opposed to delayed sentinel lymph node biopsies. The
importance of this, is to identify any differences in disease-free status
or reported deaths from melanoma between these sub-groups.

Competing interests:
None declared

Competing interests: No competing interests

06 July 2006
Chidi C Ekwobi
Clinical Fellow in Plastic Surgery
St Thomas' Hospital, Lambeth Palace Road, London, SE1 7EH