Discussion
The benefits of adopting this approach in the management of these
patients are severalfold. Firstly, these small volume recurrences often
offer no intra-operative tactile or palpable feedback to the surgical
team, so the tissue staining provides clear visual feedback that the
correct tissue has been encountered. Secondly, wide local resection of
these lesions is then permissible with increased confidence that the
primary objective of the surgery will be achieved, and thirdly this will
be done with minimal risk to the RLN and parathyroid glands.
Furthermore, the immediate post resection ultrasound image can provide
additional radiological certainty of surgical success. This has been
reported in the literature and a clear reduction of peri-operative
complications has been achieved in salvage surgery for these
patients5,6.
Charcoal suspension is readily available in [removed for blind peer
review]. The radiological procedure does not require additional
training for either the surgeon or radiologist. Additionally, the
injection can be performed even a few days prior to the surgery due to
long tissue retention. This may obviate the need for a radiologist to be
available during surgery. Crucially, the charcoal tattooing does not
interfere with histological analysis of the specimens
obtained5,6, although it is good practice to alert the
reporting histopathologist as to its use and location relative to the
histopathology specimen.
Charcotrace ® is a 3ml sterile suspension containing 120mg of activated
charcoal and sodium chloride in a 7ml vial. Activated Charcoal
suspensions are known to be safe to use in this fashion with no allergic
complications reported in the literature4,5,6.
In a case series of 12 rDTC lesions excised using charcoal injection in
South Korea, 1 patient had a temporary dark dot mark on the site of skin
puncture when giving the injection5. Additionally,
other injection associated complications reported in the literature
include pain and haematoma formation. Thus, during the consent process
for the procedure patients are informed that there is a small risk of a
pin prick tattoo at the site of the needle entry, alongside the other
risks of bleeding, infection, recurrent laryngeal nerve injury and
hypoparathyroidism.
The authors have provided a description of the technical process for the
safe and effective use of ultrasound guided activated charcoal
localisation for rDTC nodules in the neck. Our anecdotal experience
is that this technique reduces operative time and post-operative
complications in this cohort of patients although at time of writing we
are not able to state this categorically.