16-year-old presenting with swelling beneath the tongue and discomfort.

CT scan of the neck shows a fluid density well defined thin-walled lesion at the floor of the mouth in the sublingual and submandibular space.

Benign retention cysts of the salivary glands seen at the floor of mouth

“Rana” stands for frog in Latin as it often resembles frog’s underside on clinical examination 

Most common site is the floor of mouth involving the sublingual gland and rarely the submandibular gland. Following morphologies have been described:

 Extends into the submandibular space either along the posterior edge of myolohyoid muscle or through a deficiency in the muscle 

These appear as thin walled anechoic lesions at the floor of the mouth.

Well defined unilocular water density (0-10HU) lesion at the floor of the mouth with smooth capsules and devoid of internal septations 

. On MRI owing to the fluid nature of the contents these appear as high signal intensity on T2W and iso/hypointensity on T1W images

Plunging ranulas are seen extending into the submandibular space and the communication between the sublingual and submandibular components can have an appearance of a “tail sign” with smooth tapering anteriorly into the sublingual space 

Infected cysts / recurrent cysts can have thick walls with heterogeneous contents

Surgical resection is the treatment of choice.

References:
1. Gaillard, F. (2018). Ranula | Radiology Reference Article | Radiopaedia.org. [online] Radiopaedia.org. Available at: https://radiopaedia.org/articles/ranula [Accessed 12 Aug. 2018].
2. Kalra V, Mirza K, Malhotra A. Plunging Ranula. Journal of Radiology Case Reports. 2011;5(6):18-24. doi:10.3941/jrcr.v5i6.682.

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