The plunging ranula: diagnostic difficulties and a less invasive approach to treatment

Abstract

Plunging ranulas arise when a simple ranula extends beyond the floor of the mouth into the neck. Diagnosis is difficult even with modern imaging techniques as they mimic other neck lesions, and traditional treatment involves enucleation of the cyst from the neck. Despite this invasive surgery they tend to recur. We describe a less invasive approach to treatment and review the diagnostic pitfalls. From 2002 to 2011, eight patients presented with a plunging ranula. They were split into two groups: those for whom an incorrect diagnosis was made and those where a less invasive treatment approach was employed. Three patients were misdiagnosed with cervical lymphangioma and had inappropriately invasive surgery. Five patients with established plunging ranulas were treated using an intraoral approach alone, eliminating the need for a cervical incision. Misdiagnosis of a plunging ranula leads to extensive and unnecessary surgery. We propose an algorithm to simplify investigation that employs a low threshold for fine-needle aspiration cytology. The cases presented indicate that these lesions can be managed by a less invasive procedure than currently practised.

Introduction

The ranula is a well defined entity that was recognised over 1000 years ago in the Byzantine era. In the early 20th century, ranulas were thought to form from remnants of the branchial arches in the same way as branchial cysts, and suggestions that they arose from the sublingual gland were dismissed. It was not until 1956 that experimental studies in mice and excised human mucoceles suggested that ranulas were salivary extravasation cysts lined by connective tissue and not epithelium. In 1972 Harrison and Garrett demonstrated that the sublingual gland was the origin of the cyst. They showed that extravasated saliva induced a fibroblastic reaction that sealed the saliva in a connective tissue sac, so forming a ranula.

The plunging ranula, where the lesion dives through the mylohyoid muscle into the neck, was also documented in the last century. It tends to present as a painless, recurrent or progressive neck swelling. Sometimes a preceding history of trauma to the floor of the mouth exists, though the connection between this and the development of the ranula is not clear as the cervical swelling may develop years later. They may not be easy to diagnose, even with computed tomography (CT) or magnetic resonance imaging (MRI), as they are rare and mimic congenital lesions like lymphangiomas and haemangiomas. Since the treatment of congenital lymphatic or vascular anomalies and ranulas are different, it is essential to distinguish between the two at presentation.

The traditional surgical management of plunging ranulas has involved a two-pronged approach, one via the mouth and the other via the neck. The former removes the sublingual gland, the latter the ranula sac in conjunction with the submandibular gland. Despite aggressive treatment the recurrence rate is high, especially if the sublingual gland is not removed adequately.

The objectives of this study were to illustrate the diagnostic dilemma of plunging ranulas and provide a simple solution, and to promote a surgical approach that avoids surgery in the neck.

The cases of eight patients with plunging ranulas treated between August 2002 and August 2011 are summarised. The patients are divided into two groups: those who were misdiagnosed and received more invasive treatment than necessary (three patients), and those for whom the correct diagnosis was made at presentation and in whom a less invasive approach to treatment was employed (five patients).

Case histories

Group 1: misdiagnosis

In the first group, the common feature was a complex treatment history that masked the true pathogenesis of the lesion ( Table 1 ). In all cases the preoperative diagnosis of lymphangioma was incorrect, and a plunging ranula discovered during surgery. The reasons for the error are explained in the case histories, but in each case the origin of the submandibular mass was obscured by previous surgery, blurring the detail in the clinical history. So the optimum time to clinch the diagnosis is at the initial presentation.

Table 1
Summary of patients with plunging ranulas who were misdiagnosed.
Patient Age, years Intraoral features Previous surgery Imaging Pre-op diagnosis Surgery Definitive diagnosis Complications Recurrence
1 34 None Excision and extraoral drainage CT Lymphangioma SMG, SLG, and ranula excision Plunging ranula Minor tongue stiffness and numbness None (at 12 months)
2 26 None Excision MRI Lymphatic cyst Cervical approach, SLG and ranula excision Plunging ranula Mild ramus mandibularis weakness None (at 24 months)
3 26 None Excision and multiple aspirations CT and USS Lymphangioma Cervical approach, SLG and ranula excision Plunging ranula None (at 5 months)
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Jan 20, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on The plunging ranula: diagnostic difficulties and a less invasive approach to treatment
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