Abstract
The optimal treatment of plunging ranula does not necessarily involve excision of the ranula.
‘A feature of the literature [about ranula] is the limited experience of most authors. The number of cases reported in most articles is restricted to single figures. The evidence is anecdotal at best.’ Thus wrote McGurk in 2013 [ ]. However, this century has seen: a large clinical review of 580 ranulas, which concluded that the rate of recurrence was excessive unless the involved sublingual gland be removed without the need to excise the ranula [ ]; a review of 81 cases of plunging ranula that concluded that simple transoral excision of the associated sublingual gland without excision of the ranula should be the preferred surgical approach [ ]; and an additional 140 cases of plunging ranula treated by transoral excision of the associated sublingual gland without excision of the ranula with no recurrences [ ]. Furthermore, the largest meta-analysis of this topic analysed the results of 1428 operations on humans and found that the most reliable and successful treatment was transoral excision of the sublingual gland and that excision of the ranula was unnecessary [ , ].
Nevertheless, articles about ranula with the number of cases restricted to single figures are still seen, such as that by Kolomvos et al. recently in Oral and Maxillofacial Case Reports [ ]. They reported 3 cases of plunging ranula: one managed by removal of the ipsilateral sublingual and submandibular glands and ranula; and two by the removal of the ipsilateral sublingual gland and ranula. They stated that ‘The best treatment for a plunging ranula is excision of the lesion along with the involved gland (usually sublingual gland)’.
However, this contradicts the results of investigations of large numbers of cases of plunging ranula [ ]. Thus, removal of the ipsilateral sublingual gland alone was successful in 180 out of 187 cases (96%) and removal of the ipsilateral sublingual gland and plunging ranula was successful in 38 out of 40 cases (95%), whereas by contrast removal of the plunging ranula alone was successful in only 2 out of 26 cases (8%) [ , ]. The rare failure of removal of the ipsilateral sublingual gland alone relates to incomplete excision when a part of the sublingual gland had passed into or through the mylohyoid hiatus to extend to the submandibular space [ , , ]. And the rare success of removal of the ranula alone relates to postoperative fibrosis that seals the leak in the sublingual gland through which mucus extravasated to form the ranula [ , ]. That the removal of the sublingual gland and plunging ranula is no more successful than removal of the sublingual gland alone indicates that the removal of the plunging ranula, which entails substantial cervical dissection, is unnecessary and inappropriate.
The extension of extravasated mucus to the surface of the ipsilateral submandibular gland had led to the erroneous belief that the plunging ranula arises from this gland. This close secondary association is clearly illustrated by Jain et al. [ , ], and a lack of success of the removal of the ipsilateral submandibular gland alone (success in only 1 out of 17 cases [ , ]) confirms that the plunging ranula does not arise from this gland. Again, the success in 1 case relates to postoperative fibrosis that fortuitously sealed the leak from the sublingual gland [ , ].
Kolomvos et al. [ ] mention that ‘studies – which took place in cats – accounted that ranula may be created after ligation of the sublingual salivary duct’. This refers to an experimental investigation on the effects of ductal ligation of the major salivary glands of cat [ , ], which revealed that the sublingual gland was most resistant to obstruction and sometimes ruptured to produce an extravasation mucocele that could develop into a ranula, whereas the submandibular gland was less resistant and did not produce an extravasation mucocele. This was subsequently confirmed clinically [ ]. Thus the sublingual gland in humans, which secretes spontaneously and can secrete against a significant pressure gradient, can if damaged and extravasation of mucus occurs, overcome obstruction caused by reactive fibrosis and produce an extravasation mucocele lined by inflamed granulation tissue, which if the supply of mucus ceases, is resorbed and eventually disappears [ , ].
The mystery is how excision of the plunging ranula or the submandibular gland, which is clearly much more extensive and less conservative than transoral removal of the sublingual gland alone, can still be considered necessary or appropriate.
However, details of the optimal surgical management of plunging ranula by transoral removal of the ipsilateral sublingual gland alone are included in a recent textbook on the surgery of the salivary glands [ ], which should enable the optimal management of ranula to be widely understood, accepted and practised.
References
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