 Hello everyone, my name is Dr Sydney Levy and today I'm here to discuss the diagnosis and staging of oral tongue squamous cell malignancy. In previous vignettes we've been discussing the anatomy of the oral cavity and its subsites. Now I'd like to move along to describing the characteristics of squamous cell malignancy in this region. I have identified a case of left lateral oral tongue squamous cell malignancy which I'd like to use to demonstrate the general principles of its MR appearance and then in our next vignette we will go on to stage the tumour. So firstly I have axial sequences pre-contrast T1 without fat suppression, post-contrast T1 with fat suppression, coronal T2 weighted imaging with fat suppression and sagittal post-contrast T1 weighted imaging with fat suppression. The malignancy is identified here it is involving the lateral margin of the tongue that is the most common site of oral tongue squamous cell malignancy followed by the undersurface and the dorsum and the tip. The undersurface of the oral tongue is generally considered with the floor of mouth so if that is the site of origin of the tumour it is generally considered a floor of mouth tumour rather than an oral tongue tumour. This MRI demonstrates a T1 hypo intense tumour with respect to normal tongue mucosa. I'm now going to draw its margins for you so that you can appreciate what I'm trying to describe. The tumour itself is here you can see it more easily on the post-contrast T1 the T2 weighted imaging it is extending inferiorly into the floor of mouth here and on the sagittal imaging it is involving the undersurface of the oral tongue and the adjacent floor of mouth so therefore it is an oral tongue malignancy that has extended directly into the ipsilateral left floor of mouth. So what do we describe when we have these lesions? Firstly you need to give a dimension because staging is determined by the dimensions of the tumour. You need to look for the maximal dimension in this case it's about five centimeters in the sagittal projection. You also need to document whether there is crossing of the midline. In this case it's a challenge and the reason for that is that we have one image here where there is indeed bulging of the tumour at the level of the midline just here. Now you can't see it clearly crossover to the right side but there's certainly bulging and there would certainly be suspicion that the tumour is about to or has begun to extend to the contralateral side. Why is that important? Because that helps determine the degree of surgical resection, how much tongue needs to be removed at the time of surgery. You also need to document the depth of invasion. So the depth of invasion is a new criterion in the staging of oral cavity malignancy which was introduced in the eighth edition of the AJCC guidelines at the beginning of 2018. So at its thickest portion this tumour is clearly well more than 10 millimeters in depth of invasion so it's a high-stage tumour purely based on that. We've documented that it extends to the floor of mouth it does not extend to any other oral cavity subsites so the last thing we need to consider is what are the differentials? Could this be a base of tongue squamous cell carcinoma? No it can't be. The posterior third of tongue is spared. This is an oral tongue malignancy restricted to the anterior two-thirds. Could it be a floor of mouth malignancy spreading to the oral tongue? Its centre is really within the oral tongue and although it does extend inferiorly into the floor of mouth it would be classified as an oral tongue tumour by most radiologists. Does it look like any other lesions that occur in this region such as schwannomas? Doesn't look like a schwannoma. Schwannomas are well circumscribed in general and enhanced strongly often associated with the lingual nerve in this region. Could it be a venous malformation? It is a mass it's not really a collection of tortuous vessels so not really thinking of that. Abscesses can occur in the oral tongue however they have typical features of abscesses such as a necrotic centre and a peripheral rim. So really we have a standard case of a oral tongue squamous cell malignancy and we will move on to lymph nodes. So for lymph nodes it's important to refresh your memory on the lymph node levels. We have three abnormal lymph nodes in this patient they are in level 2a bilaterally both these lymph nodes here and then on the left hand side we have another lymph node which is heading into level 3 below the level of the inferior border of the hyoid and lastly you need to look for any evidence of distant malignancy which there isn't in this patient. So in our next vignette we will formally stage this patient according to the AJCC 8th edition guidelines TNM staging.