Instruct: Given a question, retrieve passages that answer the question.
Query: Is lymphangioma benign?
Most lymphangiomas are benign lesions that result only in a soft, slow-growing, "doughy" mass. Since they have no chance of becoming malignant, lymphangiomas are usually treated for cosmetic reasons only. Rarely, impingement upon critical organs may result in complications, such as respiratory distress when a lymphangioma compresses the airway. Treatment includes aspiration, surgical excision, laser and radiofrequency ablation, and sclerotherapy.
Acquired progressive lymphangioma (also known as "Benign lymphangioendothelioma") is a group of lymphangiomas that occur anywhere in young individuals, grow slowly, and present as bruise-like lesions or erythematous macules.
The direct cause of lymphangioma is a blockage of the lymphatic system as a fetus develops, although symptoms may not become visible until after the baby is born. The cause remains unknown. Why the embryonic lymph sacs remain disconnected from the rest of the lymphatic system is also not known.[5]
Lymphangioma circumscription can be healed when treated with a flashlamp pulsed dye laser, although this can cause port-wine stains and other vascular lesions.[12]
Also known as cystic lymphangioma and macrocystic lymphatic malformation, the growth is often a congenital lymphatic lesion of many small cavities (multiloculated) that can arise anywhere, but is classically found in the left posterior triangle of the neck and armpits. This is the most common form of lymphangioma. The malformation contains large cyst-like cavities containing lymph, a watery fluid that circulates throughout the lymphatic system. Microscopically, cystic hygroma consists of multiple locules filled with lymph. Deep locules are quite big, but they decrease in size towards the surface.
In 1976, Whimster studied the pathogenesis of lymphangioma circumscriptum, finding lymphatic cisterns in the deep subcutaneous plane are separated from the normal network of lymph vessels. They communicate with the superficial lymph vesicles through vertical, dilated lymph channels. Whimster theorized the cisterns might come from a primitive lymph sac that failed to connect with the rest of the lymphatic system during embryonic development.
A thick coat of muscle fibers that cause rhythmic contractions line the sequestered primitive sacs. Rhythmic contractions increase the intramural pressure, causing dilated channels to come from the walls of the cisterns toward the skin. He suggested that the vesicles seen in lymphangioma circumscriptum are outpouchings of these dilated projecting vessels. Lymphatic and radiographic studies support Whimsters observations. Such studies reveal that big cisterns extend deeply into the skin and beyond the clinical lesions. Lymphangiomas that are deep in the dermis show no evidence of communication with the regular lymphatics. The cause for the failure of lymph sacs to connect with the lymphatic system is not known.[5]
Lymphangiosarcoma is a malignant soft tissue tumour, whereas lymphangioma is a benign tumour occurring frequently in association with Turner syndrome. Lymphangioleiomyomatosis is a benign tumour of the smooth muscles of the lymphatics that occurs in the lungs.
Cases of lymphangioma are diagnosed by histopathologic inspection.[8] In prenatal cases, cystic lymphangioma is diagnosed using an ultrasound; when confirmed amniocentesis may be recommended to check for associated genetic disorders.
There are three distinct types of lymphangioma, each with their own symptoms. They are distinguished by the depth and the size of abnormal lymph vessels, but all involve a malformation of the lymphic system. Lymphangioma circumscriptum can be found on the skin's surface, and the other two types of lymphangiomas occur deeper under the skin.
Lymphangiomas are rare, accounting for 4% of all vascular tumors in children.[5] Although lymphangioma can become evident at any age, 50% are seen at birth,[2] and 90% of lymphangiomas are evident by 2 years of age.[2]
Microscopically, the vesicles in lymphangioma circumscriptum are greatly dilated lymph channels that cause the papillary dermis to expand. They may be associated with acanthosis and hyperkeratosis. There are many channels in the upper dermis which often extend to the subcutis (the deeper layer of the dermis, containing mostly fat and connective tissue). The deeper vessels have large calibers with thick walls which contain smooth muscle. The lumen is filled with lymphatic fluid, but often contains red blood cells, lymphocytes, macrophages, and neutrophils. The channels are lined with flat endothelial cells. The interstitium has many lymphoid cells and shows evidence of fibroplasia (the formation of fibrous tissue). Nodules (A small mass of tissue or aggregation of cells) in cavernous lymphangioma are large, irregular channels in the reticular dermis and subcutaneous tissue that are lined by a single layer of endothelial cells. Also an incomplete layer of smooth muscle also lines the walls of these channels. The stroma consists of loose connective tissue with a lot of inflammatory cells. These tumors usually penetrate muscle. Cystic hygroma is indistinguishable from cavernous lymphangiomas on histology.[5]
Lymphangiomas have traditionally been classified into three subtypes: capillary and cavernous lymphangiomas and cystic hygroma. This classification is based on their microscopic characteristics. A fourth subtype, the hemangiolymphangioma is also recognized.[2]
Cavernous lymphangioma first appears during infancy, when a rubbery nodule with no skin changes becomes obvious in the face, trunk, or extremity. These lesions often grow at a rapid pace, similar to that of raised hemangiomas. No family history of prior lymphangiomas is described.
Microcystic lymphangiomas Microcystic lymphangiomas are composed of cysts, each of which measures less than 2 cm3 in volume. Macrocystic lymphangiomas Macrocystic lymphangiomas contain cysts measuring more than 2 cm3 in volume. Mixed lymphangiomas Lymphangiomas of the mixed type contain both microcystic and macrocystic components.
Lymphangioma circumscriptum, a microcystic lymphatic malformation, resembles clusters of small blisters ranging in color from pink to dark red.[3] They are benign and do not require medical treatment, although some patients may choose to have them surgically removed for cosmetic reasons. Cavernous lymphangiomas are generally present at birth, but may appear later in the child's life.[4] These bulging masses occur deep under the skin, typically on the neck, tongue and lips,[5] and vary widely in size, ranging from as small as a centimeter in diameter to several centimeters wide. In some cases, they may affect an entire extremity such as a hand or foot. Although they are usually painless, the patient may feel mild pain when pressure is exerted on the area. They come in the colors white, pink, red, blue, purple, and black; and the pain lessens the lighter the color of the bump. Cystic hygroma shares many commonalities with cavernous lymphangiomas, and some doctors consider them to be too similar to merit separate categories. However, cystic lymphangiomas usually have a softer consistency than cavernous lymphangiomas, and this term is typically the one that is applied to lymphangiomas that develop in fetuses. They usually appear on the neck (75%), arm pit or groin areas. They often look like swollen bulges underneath the skin.
Cystic tumours of the atrioventricular nodal region, true to their name, have cystic spaces, which are lined by a single layer of histomorphologically benign epithelial cells. The appearance is similar to that of lymphangioma and this is a name that has been used for this tumour.
Superficial lymphatic malformation (also known as "Lymphangioma circumscriptum") is a congenital malformation of the superficial lymphatics, presenting as groups of deep-seated, vesicle-like papules resembling frog spawn, at birth or shortly thereafter.
The prognosis for lymphangioma circumscriptum and cavernous lymphangioma is generally excellent. This condition is associated with minor bleeding, recurrent cellulitis, and lymph fluid leakage. Two cases of lymphangiosarcoma arising from lymphangioma circumscriptum have been reported; however, in both of the patients, the preexisting lesion was exposed to extensive radiation therapy.
In 1828, Redenbacher first described a lymphangioma lesion. In 1843, Wernher gave the first case report of a cystic hygroma, from the Greek "hygro-" meaning fluid and "oma" meaning tumor. In 1965, Bill and Summer proposed that Cystic hygromas and lymphangiomas are variations of a single entity and that its location determines its classification.
Capillary lymphangiomas Capillary lymphangiomas are composed of small, capillary-sized lymphatic vessels and are characteristically located in the epidermis. Cavernous lymphangiomas Composed of dilated lymphatic channels, cavernous lymphangiomas characteristically invade surrounding tissues. Cystic hygromas Cystic hygromas are large, macrocystic lymphangiomas filled with straw-colored, protein-rich fluid. Hemangiolymphangioma As suggested by their name, hemangiolymphangiomas are lymphangiomas with a vascular component.
Treatment for cystic hygroma involves the removal of the abnormal tissue; however complete removal may be impossible without removing other normal areas. Surgical removal of the tumor is the typical treatment provided, with the understanding that additional removal procedures will most likely be required as the lymphangioma grows. Most patients need at least two procedures done for the removal process to be achieved. Recurrence is possible but unlikely for those lesions able to be removed completely via excisional surgery.[9] Radiotherapy and chemical cauteries are not as effective with the lymphangioma than they are with the hemangioma.[10] Draining lymphangiomas of fluid provides only temporary relief, so they are removed surgically. Cystic Hygroma can be treated with OK432 (Picibanil).
One of the most important factors in classifying a tumor as benign or malignant is its invasive potential. If a tumor lacks the ability to invade adjacent tissues or spread to distant sites by metastasizing then it is benign, whereas invasive or metastatic tumors are malignant. For this reason, benign tumors are not classed as cancer. Benign tumors will grow in a contained area usually encapsulated in a fibrous connective tissue capsule. The growth rates of benign and malignant tumors also differ; benign tumors generally grow more slowly than malignant tumors. Although benign tumors pose a lower health risk than malignant tumors, they both can be life-threatening in certain situations. There are many general characteristics which apply to either benign or malignant tumors, but sometimes one type may show characteristics of the other. For example, benign tumors are mostly well differentiated and malignant tumors are often undifferentiated. However, undifferentiated benign tumors and differentiated malignant tumors can occur. Although benign tumors generally grow slowly, cases of fast-growing benign tumors have also been documented. Some malignant tumors are mostly non-metastatic such as in the case of basal cell carcinoma. CT and chest radiography can be a useful diagnostic exam in visualizing a benign tumor and differentiating it from a malignant tumor. The smaller the tumor on a radiograph the more likely it is to be benign as 80% of lung nodules less than 2 cm in diameter are benign. Most benign nodules are smoothed radiopaque densities with clear margins but these are not exclusive signs of benign tumors.
Finally, lymphangiomas may be described in stages, which vary by location and extent of disease. In particular, stage depends on whether lymphangiomas are present above or superior to the hyoid bone (suprahyoid), below or inferior to the hyoid bone (infrahyoid), and whether the lymphangiomas are on one side of the body (unilateral) or both (bilateral).[2]
Cystic lymphangioma that emerges during the first two trimesters of pregnancy is associated with genetic disorders such as Noonan syndrome and trisomies 13, 18, and 21. Chromosomal aneuploidy such as Turner syndrome or Down syndrome[6] were found in 40% of patients with cystic hygroma.[7]