Mushrooms in the valley
So, I’m back after 2 1/2 weeks away in the wilds of Yorkshire near the Gothic town of Whitby. It was quite a marvellous holiday with lots of mountain biking, body boarding and walking……but no Internet! This was both a tremendous relief as peace descended in the digital part of my brain, but also an interesting reminder of just how much we rely on digital access to stay in touch and to get things done. No worry though, despite my out of office messages I came back to >1500 emails, roughly 30 would be regarded as important…anyway. I could have written about repetitive strain injury to my delete button finger, but rather I am thinking back to the wonderful mountain biking in Dalby forest and the sort of injuries that I might have sustained whilst attempting the more difficult routes.
So enough of my Jollidays, back to medicine and possibly one of my favourite diagnoses in the ED, I’m not sure why, possibly because I’ve seen quite a few in cyclists (and ED docs love cycling), but more likely I just like the name. I also think that is an under-diagnosed condition with clinical signs attributed to other conditions such as haematoma.
So what is it? Well, if you don’t know the name you might recognise the condition because I’ll bet you will have seen it at some point if you’ve been around the ED for a few years or so. A Morel-Lavallée lesion occurs when the superfical fat and skin separate from the underlying fascia to produce a potential space which then fills with fluid. These are often initially mistaken for simple haematomas but you can usually clinically distinguish them as they are more mobile, more ‘squishable’ and often demonstrate fluctuating size through the day as activity or posture changes. They are often tricky to spot in the early stages, and they may be missed on first presentation with signs becoming more obvious over days, weeks or sometimes months.
So, in the ED you might see this when a patient first comes to you having sustained a shearing injury with a subcutaneous swelling, but more likley you would suspect this injury in someone who returns days to weeks later with a persistent, fluctuant swelling that does not seem to be going away.
In the literature it is commonly described in relation to severe pelvic injuries, particularly those involving patients being run over where there are severe shear forces applied to the pelvic area and they are of particular concern to pelvic surgeons as they can interfere with operative management. I’m not so concerned with that group in this post as those patients will be heading to theatre under the care of the Orthopaedic surgeons. Rather I’m interested in those lesions that we might see and manage in the ED.
The separation of superficial tissues from fat requires a fairly significant shearing force that drags and tears the skin and fat from the underlying fascia. I guess that’s why we have seen in cyclists as the typical fall at speed, followed by an impact at an angle (as one hits the road or track) lends itself to this sort of injury. Typically they occur around bony protuberances such as the hip and knee as these are areas where the underling tissues are relatively fixed yet the skin is not. The advent of artificial pitches and hard surface playing environments may also be a factor, but that’s just my opinion, no evidence to back that up really…
The sort of crash that might cause this sort of injury is not uncommon in cyclists, particularly track cyclists, and as Virchester is home to the greatest Velodrome in the world we have seen many riders from first timers right through to Olympic champions over the years. The description attributed to Sir Chris Hoy’s injury back in 2009 is of a Morel-Lavallée lesion and if you look at the footage from the crash you get a real idea of the shear forces involved in the injury mechanism. If you don’t watch the entire Kierin then skip to 2:50 & then slo-mo at 3:45 to see the crash.
There is also an absolutely fantastic personal account of a bicycle sustained M-L lesion on this blog by Fatheral, plus the blog has a great series of personal photos of what an M-L lesion looks like – although their lesion ended up with surgery (not always needed – see below).
Although MR is advocated by radiologists as an optimal way of looking for these lesions I have found USS to be an excellent tool to define the nature and extent of these lesions. There are a few nice examples of what you see on USS in this paper from the Journal of Ultrasound Medicine, but you should be able to predict what you would see. A fluid collection superficial to the fascia that is easily compressible. Some good pics here as well. The one thing to think about when you are attempting ultrasound is that these are very ‘squishable’ so you can miss them if you are heavy handed. A very light touch may be needed to avoid ‘squashing’ the fluid away from your field of view.
So what to do about it? I have not found definitive advice on treatment but there appear to be a number of options.
- 1. Simple compression – reported as successful in some case series.
- 2. Serial aspiration under USS (done this several times and works well – but time consuming as daily repeats with compression bandaging between times).
- 3. Insertion of surgical vacuum drain.
- 4. Sclerodesis with something a tetracycline/doxycycline
So my personal plan with these lesions is, as always, dependent on the patient characteristics and size of the lesion. In patients with very small lesions then I would go for compression, particularly around the knee where compression is easy to achieve. For lesion around the hip it’s pretty difficult to get a compression bandage on in any effective manner so I tend to go straight for aspiration in those lesions, repeating on a daily or bi-daily manner under USS guidance. USS also gives you a really good idea of whether you are winning and if not then it’s a referral over to the surgeons for a vacuum drain.
So, a favourite diagnosis and although not common it is one that we can do something about and it’s got a great name….what more do you want
….well, to be honest I’d like to see someone do a proper review of this lesion for the FCEM exam. I think it would make a great CTR.
- Nice review on the radiological features on MR
- Bio of Morel-Lavallée
- Paper on sports related knee M-L injuries
- Sclerodesis therapy
…and thanks to Nat for sorting my accents out