Three additional diagnostic and management techniques are often used in patients with midline neck masses, and they all have flaws, Dr. Propst noted. “Some surgeons stretch the skin over the cyst and if a white colored mass shows through, it is believed that it will more likely be a dermoid cust than TGDC,” he said. Unfortunately, this method has not proven reliable in the literature. “Others automatically do a Sistrunk for every cyst in the midline region. And a third way is to base your decision on the ultrasound report and do the appropriate surgery, but, as previous studies have shown, those reports can be wrong.”
Explore this issue:July 2013
Dr. Propst said he has been using a fourth technique to distinguish between TGDCs and dermoid cysts. During surgery, he said, he will minimally expose the cyst and then aspirate it with a needle. Whatever substance is removed tells him what type of cyst is present. “If it’s mucus, then it’s a TGDC; if it’s white and ‘cottage cheesy’ in appearance, then it’s a dermoid,” he said. This simple finding has a very high predictive value, Dr. Propst said, and thus helps him reduce the need for more extensive surgery than the patient requires. But it doesn’t solve the larger problem of needing to know definitively ahead of time what type of midline mass is present to help counsel parents and plan peri-operative management. For that, Dr. Propst’s new method for interpreting ultrasound findings is the best option. But is it ready for prime time?
“We have a bit more work to do in terms of reproducing our results, but I am very confident that this will ultimately make it into clinical practice,” Dr. Propst said. Part of that confidence, he noted, comes from the quality of the current study design. “What we ended up with was a prospective, blinded evaluation of retrospectively acquired ultrasound imaging; I don’t think this has been done before in these patients,” he said. Moreover, “no previous study has included as many patients as we did, to assess ultrasound’s ability to differentiate between these two masses.”
Dr. Cunnane agreed that more research is needed. Still, she stressed that the study by Dr. Propst and his colleagues “has more cases of its type than any other study I know of.” She also gave the researchers kudos for coupling ultrasound readings with pathology reports. “Overall, this is a very well-done study,” she said. “I look forward to their efforts at replicating the results in a prospective fashion.”