Overview
Plunging ranula is a rare clinical entity characterized by a large, deep neck swelling that originates from extravasated saliva, typically from the sublingual gland. This condition often presents as a cystic lesion extending from the floor of the mouth through a defect in the mylohyoid muscle into the neck. Understanding its pathophysiology, epidemiology, clinical presentation, and management is crucial for effective treatment and minimizing recurrence rates. Historically, plunging ranula has been underreported, but recent studies have contributed significantly to our knowledge base, highlighting the importance of meticulous surgical techniques and appropriate imaging modalities for accurate diagnosis and management.
Pathophysiology
The pathophysiology of plunging ranula primarily involves extravasation of saliva from the sublingual gland, often due to trauma or ductal obstruction [PMID:3580808]. This extravasation leads to the formation of a large, fluid-filled cyst that can extend beyond the oral cavity into the neck region. The sublingual gland, located beneath the tongue, has multiple ducts that drain into the submandibular duct or directly into the oral cavity. When these ducts are compromised, saliva accumulates, forming a pseudocyst that can penetrate through the mylohyoid muscle, creating a connection between the oral cavity and the cervical region. This mechanism underscores the importance of addressing both the primary site of extravasation and the cervical extension to prevent recurrence.
Epidemiology
Epidemiological data on plunging ranula remain limited, but several case series have provided valuable insights. A retrospective analysis of 95 consecutive cases from January 2001 to February 2010 contributed significantly to the understanding of this condition's global prevalence [PMID:21328001]. Since 1910, only 139 procedures in 89 patients have been reported in the English literature, indicating that plunging ranula is indeed a rare entity [PMID:3580808]. The rarity of reported cases suggests underdiagnosis or misdiagnosis, possibly due to its nonspecific clinical presentation. Despite the limited number of cases, these studies highlight the recurrent nature of the condition, with multiple patients requiring further interventions after initial treatments, emphasizing the need for comprehensive management strategies.
Clinical Presentation
Clinical presentation of plunging ranula can vary but typically includes a large, painless swelling in the neck that may extend from the floor of the mouth. Twelve patients in a notable series had undergone previous surgeries elsewhere, indicating a high likelihood of recurrence or persistent disease [PMID:21328001]. The swelling often extends anteriorly through a defect in the mylohyoid muscle in two cases and posteriorly in five cases [PMID:8763376]. Patients may present with a palpable mass that can be firm and non-tender, sometimes mimicking other neck pathologies such as thyroglossal duct cysts or branchial cleft anomalies. The absence of oral floor swelling in some cases can complicate initial diagnosis, necessitating thorough clinical examination and appropriate imaging to rule out ectopic sublingual gland involvement [PMID:8763376].
Diagnosis
Accurate diagnosis of plunging ranula is crucial for effective management. Imaging plays a pivotal role in confirming the diagnosis and assessing the extent of the lesion. Sonography and CT imaging are commonly used to monitor volume changes and delineate the extent of the cystic mass [PMID:16687549]. However, MRI has emerged as a valuable tool, correctly identifying the diagnosis in three cases where other modalities might have been less definitive [PMID:24861405]. MRI provides detailed anatomical information, helping to differentiate plunging ranula from other neck masses and identifying potential connections between the oral and cervical components via a hiatus in the mylohyoid muscle [PMID:3580808]. In cases where a cervical mass is present without obvious oral floor swelling, a cervical approach may be preferred to explore potential ectopic sublingual gland locations [PMID:8763376].
Management
The management of plunging ranula aims to eradicate the source of saliva extravasation and address the cervical extension effectively to minimize recurrence. Several treatment modalities have been explored, each with varying outcomes.
Sclerotherapy
Intralesional sclerotherapy using agents like OK-432 has shown promising results. In a study involving 21 patients, significant outcomes were observed, with total shrinkage in 33.3%, near-total shrinkage in 19%, and marked shrinkage in 19% of cases [PMID:16687549]. While sclerotherapy can be effective, the recurrence rate after individual injections remains relatively high at 47%, though it drops to 14% following the final session, indicating the potential for this approach as a primary treatment [PMID:16687549].
Surgical Approaches
Surgical excision remains a cornerstone in the definitive treatment of plunging ranula. Total removal of the sublingual gland along with evacuation of cystic contents via an intraoral approach has led to complete resolution within two months in several cases [PMID:24861405]. A series of 81 cases treated surgically with transoral excision of the sublingual gland and evacuation of ranula contents reported a mean operating time of 75.3 minutes, with only one recurrence necessitating further excision of a sublingual gland remnant [PMID:21328001]. Another study highlighted the efficacy of a cervical approach, where all seven patients underwent successful pseudocyst extirpation without observed recurrences, even in cases where total sublingual gland excision was not performed [PMID:8763376]. Incision of the pseudocyst prior to other procedures can facilitate subsequent interventions and reduce the risk of transient complications such as facial paralysis [PMID:8763376].
Recurrence Rates
Recurrence rates vary significantly based on the treatment modality. Incision and drainage have the highest recurrence rate at 70%, followed by marsupialization at 53%, and excision of the cyst in the neck at 85% [PMID:3580808]. In contrast, excision of the sublingual gland via either cervical or intraoral routes shows a markedly lower recurrence rate of 2%, underscoring the importance of addressing the primary source of saliva extravasation [PMID:3580808].
Complications
Despite effective management strategies, complications can arise from both sclerotherapy and surgical interventions. Side effects from sclerotherapy include fever lasting 2-3 days in 12 patients, swelling for 3-5 days in 10 patients, and mild odynophagia for 1-2 days in 7 patients, with one severe case of odynophagia [PMID:16687549]. Surgical approaches can lead to minor and transient complications such as trauma to the submandibular duct, necessitating additional submandibular gland excision in two cases [PMID:21328001]. These complications highlight the need for careful surgical technique and close postoperative monitoring to ensure optimal outcomes.
Prognosis & Follow-up
The prognosis for patients with plunging ranula is generally good with appropriate management, though recurrence remains a concern. Studies indicate that meticulous surgical techniques are crucial to prevent recurrence, with only one patient experiencing recurrence after comprehensive excision [PMID:21328001]. Total sublingual gland removal and cyst evacuation have shown no recurrence during follow-up periods in three cases [PMID:24861405]. The cervical approach, particularly for salvage surgeries following intraoral procedures, has demonstrated efficacy with no observed recurrences in a series of cases [PMID:8763376]. Regular follow-up imaging and clinical assessments are essential to monitor for any signs of recurrence and ensure long-term success.
Key Recommendations
References
1 Rho MH, Kim DW, Kwon JS, Lee SW, Sung YS, Song YK et al.. OK-432 sclerotherapy of plunging ranula in 21 patients: it can be a substitute for surgery. AJNR. American journal of neuroradiology 2006. link 2 Li J, Li J. Correct diagnosis for plunging ranula by magnetic resonance imaging. Australian dental journal 2014. link 3 Samant S, Morton RP, Ahmad Z. Surgery for plunging ranula: the lesson not yet learned?. European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery 2011. link 4 Ichimura K, Ohta Y, Tayama N. Surgical management of the plunging ranula: a review of seven cases. The Journal of laryngology and otology 1996. link 5 Parekh D, Stewart M, Joseph C, Lawson HH. Plunging ranula: a report of three cases and review of the literature. The British journal of surgery 1987. link