A double lip is a rare anatomical variation characterized by the presence of a redundant fold of excess tissue, primarily mucosa and submucosa, on the inner surface of the lip. This non-threatening condition is not typically noticed when the mouth is at rest, but it becomes visible when the lip is tensed, such as during a broad smile. The double lip is an anomaly that affects facial appearance and may be present from birth or develop later in life.
Anatomical Description
The double lip appearance results from an accessory fold of hypertrophied tissue located proximal to the vermilion border, the line separating the outer skin of the lip from the inner mucosa. This redundant tissue is typically composed of hyperplastic minor salivary glands and excessive areolar tissue within the submucosa, but it usually lacks muscle fibers. The condition most frequently affects the upper lip, though it can occasionally appear on the lower lip or both simultaneously.
When the mouth is relaxed, the excess fold remains hidden against the gums and teeth. However, when the orbicularis oris muscle contracts during smiling or speaking, the main lip is pulled taut, causing the soft accessory fold to droop. This action makes the redundant tissue visible, creating the illusion of a second, parallel lip or a “cupid’s bow” shape. This prominent fold is often bilateral and may be separated by a small midline constriction where the labial frenulum attaches.
Etiology: Why It Develops
The origins of a double lip are categorized into congenital and acquired causes. The congenital form, present from birth, is a developmental anomaly occurring during the second or third month of gestation. Normally, the inner mucosal part of the lip and the outer smooth part fuse, but in this condition, a persistent horizontal sulcus remains, leading to the excessive tissue fold.
The acquired form is less common and can arise from trauma, such as an injury to the lip, or from chronic habits. These habits include repeatedly sucking the lip between teeth or dentures, which causes reactive hyperplasia of the tissue. The double lip is also strongly associated with a rare genetic disorder known as Ascher Syndrome.
Ascher Syndrome
Ascher Syndrome is defined by a triad of symptoms: the double lip, blepharochalasis (a condition affecting the eyelids), and non-toxic thyroid enlargement (goiter). Blepharochalasis involves recurrent, painless swelling of the upper eyelids that can lead to skin thinning and drooping. While the double lip is a defining feature, the goiter is present in only 10 to 50 percent of cases.
Functional and Social Impact
For many individuals, the double lip is primarily an aesthetic issue rather than a functional one. The noticeable alteration in appearance when smiling can be a source of significant self-consciousness or emotional distress, affecting self-esteem and social interactions.
In some cases, the excess tissue can create minor functional difficulties, such as interference with speaking, a lisp, or problems during mastication. The redundant fold may also occasionally be bitten or sucked between the teeth, leading to further irritation.
Management and Surgical Correction
Management of a double lip is pursued when the condition causes aesthetic concerns or functional impairment. Since the anomaly is benign, surgical correction is the standard treatment option for those seeking a change.
The most common and effective procedure is a simple surgical excision, often performed under local anesthesia. This technique involves making an elliptical incision to remove the redundant fold of mucosa and the underlying hyperplastic submucosal tissue. The incision edges are then sutured together in a primary closure, which restores a more normal lip contour. The goal of the surgery is to achieve a satisfactory aesthetic result and eliminate functional difficulties, with recurrence being rare.