A ranula is a mucus extravasation cyst involving a sublingual gland and is a type of

mucocele A mucocele is a distension of a hollow organ or cavity because of mucus buildup. By location Oral Oral mucocele is the most common benign lesion of the salivary glands generally conceded to be of traumatic origin. It is characterized by the pool ...

found on the floor of the mouth. Ranulae present as a swelling of

connective tissue Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...

consisting of collected

mucin Mucins () are a family of high molecular weight, heavily glycosylated proteins (glycoconjugates) produced by epithelial tissues in most animals. Mucins' key characteristic is their ability to form gels; therefore they are a key component in most ...

from a ruptured

salivary gland The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands (parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. Salivary gla ...

caused by local trauma. If small and asymptomatic further treatment may not be needed, otherwise minor oral surgery may be indicated.

Signs and symptoms

A ranula usually presents as a translucent, blue, dome-shaped, fluctuant swelling in the tissues of the floor of the mouth. If the lesion is deeper, then there is a greater thickness of tissue separating from the oral cavity and the blue translucent appearance may not be a feature. A ranula can develop into a large lesion many centimeters in diameter, with resultant elevation of the tongue and possibly interfering with swallowing (

dysphagia Dysphagia is difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, in some contexts it is classified as a disease#Terminology, condition in its own right. It may be a sensation that suggests difficulty in the passag ...

). The swelling is not fixed, may not show blanching, and is non-painful unless it becomes secondarily infected. The usual location is lateral to the midline, which may be used to help distinguish it from a midline

dermoid cyst A dermoid cyst is a teratoma of a cystic nature that contains an array of developmentally mature, solid tissues. It frequently consists of skin, hair follicles, and sweat glands, while other commonly found components include clumps of long hair ...

. A cervical ranula presents as a swelling in the neck, with or without a swelling in the mouth. In common with other mucoceles, ranulae may rupture and then cause recurrent swelling. Ranulae may be asymptomatic, although they can fluctuate rapidly in size, shrinking and swelling, making them difficult to detect.

Complications

* Infection * Repeated trauma * Bursting and reformation * Dysphagia (in the case of a large ranula)

Causes

Minor trauma to the floor of the mouth is thought to damage the delicate ducts that drain saliva from the sublingual gland into the oral cavity. The lesion is a mucous extravasation cyst (mucocele) of the floor of mouth, although a ranula is often larger than other mucoceles (mainly because the overlying mucosa is thicker). They can grow so large that they fill the mouth. The most usual source of the

spillage is the sublingual salivary gland, but ranulae may also arise from the submandibular duct or the minor salivary glands in the floor of the mouth. A cervical ranula occurs when the spilled mucin dissects its way through the

mylohyoid muscle The mylohyoid muscle or diaphragma oris is a paired muscle of the neck. It runs from the mandible to the hyoid bone, forming the floor of the oral cavity of the mouth. It is named after its two attachments near the molar teeth. It forms the floor ...

, which separates the sublingual space from the

submandibular space The submandibular space is a fascial space of the head and neck (sometimes also termed fascial spaces or tissue spaces). It is a potential space, and is paired on either side, located on the superficial surface of the mylohyoid muscle between the ...

, and creates a swelling in the neck. It may occur following rupture of a simple ranula. Rarely, ranulae may extend backwards into the parapharyngeal space.

Mechanism

The fluid within a ranula has the viscous, jellylike consistency of

egg white Egg white is the clear liquid (also called the albumen or the glair/glaire) contained within an egg. In chickens it is formed from the layers of secretions of the anterior section of the hen's oviduct during the passage of the egg. It forms arou ...

Diagnosis

The

histologic Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...

appearance is similar to

s from other locations. The spilled mucin causes a granulation tissue to form, which usually contains foamy

histiocyte A histiocyte is a vertebrate cell that is part of the mononuclear phagocyte system (also known as the reticuloendothelial system or lymphoreticular system). The mononuclear phagocytic system is part of the organism's immune system. The histiocyt ...

Ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...

and

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...

may be useful to image the lesion. A small squamous cell carcinoma obstructing the Wharton duct may require clinical examination to be distinguished from a ranula.

Criteria

* Mostly seen in young children and adolescents, both sexes are equally affected. Swelling in floor of mouth, which may be painful. Mostly unilateral, on one side of frenulum. * Shape is spherical * Size varies from 1 – 5 cm in diameter * Color is pale blue with characteristics semi transparent appearance. * Surface is smooth and mucous membrane is mobile over the swelling. * Tenderness is absent * Fluctuation test is positive * Transillumination test is positive * Cervical lymph nodes are not enlarged. * May or may not have prolongation in the neck.

Classification

A ranula is a type of mucocele, and therefore could be classified as a disorder of the salivary glands. Usually a ranula is confined to the floor of the mouth (termed a "simple ranula"). An unusual variant is the cervical ranula (also called a plunging or diving ranula), where the swelling is in the neck rather than the floor of the mouth. The term ranula is also sometimes used to refer to other similar swellings of the floor of mouth such as true salivary duct cysts,

s and

cystic hygroma A cystic hygroma is an abnormal growth that usually appears on a baby's neck or head. It consists of one or more cysts and tends to grow larger over time. The disorder usually develops while the fetus is still in the uterus, but can also appear a ...

s. The Latin word ''rana'' means "frog" (ranula = "little frog").

Treatment

Treatment of ranulae usually involves removal of the sublingual gland. Surgery may not be required if the ranula is small and asymptomatic.

Marsupialization 400px, Marsupialization Marsupialization is the surgical technique of cutting a slit into an abscess or cyst and suturing the edges of the slit to form a continuous surface from the exterior surface to the interior surface of the cyst or abscess. ...

may sometimes be used, where the intra-oral lesion is opened to the oral cavity with the aim of allowing the sublingual gland to re-establish connection with the oral cavity.

Epidemiology

The lesion is usually present in children. Ranulae are the most common pathologic lesion associated with the sublingual glands.

Other animals

Image:Ranula-dog.jpg, Ranula in a dog Image:Resektion-glandula-mandibularis-sublingualis-dog.jpg, excision of both mandibular and major sublingual glands in a dog

References

*Kahn, Michael A. Basic Oral and Maxillofacial Pathology. Volume 1. 2001.

External links

* {{Oral pathology Salivary gland pathology