AVMs are probably present from birth, but dont necessarily cause any symptoms. Frequent nosebleeds are the most common symptom and can significantly affect quality of life. History
Several 19th century English physicians, starting with Henry Gawen Sutton (1836–1891) and followed by Benjamin Guy Babington (1794–1866) and John Wickham Legg (1843–1921), described the most common features of HHT, particularly the recurrent nosebleeds and the hereditary nature of the disease. The French physician Henri Jules Louis Marie Rendu (1844–1902) observed the skin and mucosal lesions, and distinguished the condition from hemophilia. The Canadian-born Sir William Osler (1849–1919), then at Johns Hopkins Hospital and later at Oxford University, made further contributions with a 1901 report in which he described characteristic lesions in the digestive tract. The English physician Frederick Parkes Weber (1863–1962) reported further on the condition in 1907 with a series of cases. The term "hereditary hemorrhagic telangiectasia" was first used by the American physician Frederic M. Hanes (1883–1946) in a 1909 article on the condition.The diagnosis of HHT remained a clinical one until the genetic defects that cause HHT were identified by a research group at Duke University Medical Center, in 1994 and 1996 respectively. In 2000, the international scientific advisory committee of cureHHT formerly called the HHT Foundation International published the now widely used Curaçao criteria. In 2006, a group of international experts met in Canada and formulated an evidence-based guideline, sponsored by cureHHT. This guideline has since been updated in 2020 and can be found here. == References ==
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 mucin 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, which separates the sublingual space from the submandibular space, 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. Diagnosis
The histologic appearance is similar to mucoceles from other locations. The spilled mucin causes a granulation tissue to form, which usually contains foamy histiocytes. Ultrasound and magnetic resonance imaging 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.