Huge Plunging Ranula Extending Into Multiple Spaces

Significant Statement

Plunging ranulas extend to the submandibular space through the posterior edge or defect of the mylohyoid muscle, and sometimes involve other adjacent spaces such as parapharyngeal space. However, a huge plunging ranula extending into multiple spaces, especially contralateral spaces, is extremely rare. Fine needle aspiration is very useful for the diagnosis of cystic lesions originating from salivary glands, and the positive for amylase confirms salivary gland origin.

A 25-year-old male was referred to our department for painless soft swelling of the bilateral neck after marsupialization of a right intraoral ranula at another hospital (Figure 1). There was only a scar on the right oral floor. Computed tomography revealed a well-circumscribed, lobulated, homogeneous low-density cystic lesion (14.5 cm × 10.7 cm × 7.2 cm) in the right lateral neck including submandibular and parapharyngeal spaces as well as submental and left submandibular region (Figure 2). Magnetic resonance imaging showed a well-circumscribed, cystic lesion having high signal intensity on T2-weighted images (Figure 3). Both imaging did not show the tail sign. Ultrasonography revealed a compressible, homogenous, hypoechoic lesion without blood flows. Fine needle aspiration revealed yellowish viscous fluid with high amylase. The cystic lesion was clinically and radiologically diagnosed as a right plunging ranula. The plunging ranula was extended into the submandibular and parapharyngeal spaces from the posterior edge of the mylohyoid muscle. The patient underwent right sublingual gland removal with drainage of remaining saliva in the plunging ranula under general anesthesia. The postoperative course was uneventful, and there was no recurrence 18 months after the surgery.

Figure 1.

Facial view shows bilateral cervical swelling.

Figure 2.

Computed tomography. (A, B) Axial images show bilateral submandibular cystic lesion without tail sign. (C, D) Coronal images show the lesion extends into parapharyngeal and supraclavicular regions. Arrows indicate a cystic lesion.

Figure 3.

Magnetic resonance imaging (A, B: axial images, C: coronal image). T2-weighted images show a well-circumscribed, cystic lesion without tail sign having high signal intensity. Arrows indicate a cystic lesion.

Plunging ranulas extend from the sublingual gland to the submandibular space through the posterior edge or defect of the mylohyoid muscle, and rarely involve other adjacent spaces such as parapharyngeal space.^1-3 However, a huge plunging ranula extending into multiple spaces, especially contralateral spaces, is extremely rare. ¹ To our knowledge, the present case is the hugest plunging ranula with the bilateral space extension. Plunging ranulas sometimes mimic other neck lesions and the misdiagnosis leads to extensive and unnecessary surgery. ⁴ The differential diagnosis of submandibular cystic lesions includes plunging ranula, submandibular gland mucocele, abscess, lymphatic malformation, dermoid cyst, and branchial cyst.^4,5 Because clinical findings cannot be distinguished from one another, diagnosis relies on radiological imaging and fluid aspiration. ⁴ Although tail sign is the characteristic imaging feature of the plunging ranula, plunging ranulas do not always show tail sign. ⁵ Fine needle aspiration is very helpful to diagnose cystic lesions originating from salivary glands, and the positive for amylase indicates salivary gland origin. A mucous and serous aspiration confirm a sublingual gland and submandibular gland origin, respectively. ⁵ Therefore, the present case with high amylase mucous fluid was diagnosed as a plunging ranula.

Conservative or surgical treatments are performed for plunging ranulas. Conservative treatments include aspiration, injection of sclerosing agents, irradiation, marsupialization, and incision and drainage. ⁵ Recent proportion meta-analysis of plunging ranula showed that sublingual gland removal has higher cure rates than OK-432 injection. ⁶ Furthermore, in a prospective, randomized, double-blinded placebo-controlled study, sclerotherapy with OK-432 in ranulas is a very effective treatment for intraoral ranulas, while possibly less useful in plunging ranulas. ⁷ In the present case with huge plunging ranula extending into multiple spaces, sublingual gland removal with drainage of the plunging ranula was performed in intraoral approach.