To evaluate common pitfalls in diagnosing complicated plunging ranula, either due to misidentification of plunging ranula or alternative pathology (i.e. false negatives or false positives, respectively).
A review of cases of plunging ranula seen in Middlemore Hospital, New Zealand, was performed. Diagnostically uncertain cases were identified and reviewed, taking particular note of clinical, radiological and surgical findings.
From our database, 12 cases were found to have had a complicated diagnosis of plunging ranula. Ten cases were false negatives: four were treated as abscesses, four as simple cysts, one as a thyroglossal cyst and one as a cystic hygroma. Two cases were false positives: one was found to be a thyroglossal cyst and the other a lipoma.
The diagnosis of plunging ranula is usually straightforward, with simple surgical management. Misdiagnosis can lead to recurrence of symptoms and inappropriate management, with the associated risks, complications and frustrations of surgery.