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.