Lymphangiomas are rare, accounting for 4% of all vascular tumors in children. Although lymphangioma can become evident at any age, 50% are seen at birth, and 90% of lymphangiomas are evident by 2 years of age.

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 cystic hygroma, large cysts can cause dysphagia, respiratory problems, and serious infection if they involve the neck. Patients with cystic hygroma should receive cytogenetic analysis to determine if they have chromosomal abnormalities, and parents should receive genetic counseling because this condition can recur in subsequent pregnancies.

Complications after surgical removal of cystic hygroma include damage to the structures in the neck, infection, and return of the cystic hygroma.

A cystic hygroma, also known as cystic lymphangioma and macrocystic lymphatic malformation, is an often congenital multiloculated lymphatic lesion 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. It 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. In the depth, the locules are quite big but they decrease in size towards the surface.

Cystic hygromas are benign, but can be disfiguring. It is a condition which usually affects children; very rarely it can present in adulthood.

Cystic hygroma is also known as lymphatic malformation. Currently, the medical field prefers to use the term lymphatic malformation because the term cystic hygroma means water tumor. Lymphatic malformation is more commonly used now because it is a sponge-like collection of abnormal growth that contains clear lymphatic fluid. The fluid collects within the cysts or channels, usually in the soft tissue. Cystic hygromas occur when the lymphatic vessels that make up the lymphatic system are not formed properly. There are two types of lymphatic malformations. They are macrocystic lymphatic malformations, large cysts, and microcystic, small cysts. A person may have only one kind of the malformation or can have a mixture of both macro and micro cysts.

Cystic hygroma can be associated with a nuchal lymphangioma or a fetal hydrops. Additionally, it can be associated with Turner syndrome or with Noonan syndrome.

A lethal version of this condition is known as Cowchock Wapner Kurtz syndrome that, in addition to cystic hygroma, includes cleft palate and lymphedema, a condition of localized edema and tissue swelling caused by a compromised lymphatic system.

A baby with a prenatally diagnosed cystic hygroma should be delivered in a major medical center equipped to deal with neonatal complications, such as a neonatal intensive care unit. An obstetrician usually decides the method of delivery. If the cystic hygroma is large, a cesarean section may be performed. After birth, infants with a persistent cystic hygroma must be monitored for airway obstruction. A thin needle may be used to reduce the volume of the cystic hygroma to prevent facial deformities and airway obstruction. Close observation of the baby by a neonatologist after birth is recommended. If resolution of the cystic hygroma does not occur before birth, a pediatric surgeon should be consulted.

Cystic hygromas that develop in the third trimester, after thirty weeks gestation, or in the postnatal period are usually not associated with chromosome abnormalities. There is a chance of recurrence after surgical removal of the cystic hygroma. The chance of recurrence depends on the extent of the cystic hygroma and whether its wall was able to be completely removed.

Treatments for removal of cystic hygroma are surgery or sclerosing agents which include:

- Bleomycin

- Doxycycline

- Ethanol (pure)

- Picibanil (OK-432)

- Sodium tetradecyl sulfate

A placental site nodule, abbreviated PSN, is benign remnant from a previous pregnancy.

Benign fibrous histiocytomas (also known as dermal dendrocytoma, dermatofibroma, fibrous dermatofibroma, fibrous histiocytoma, fibroma simplex, nodular subepidermal fibrosis, and sclerosing hemangioma) are benign skin growths.

A papillary hidradenoma, also hidradenoma papilliferum, is a sharply circumscribed nodule or benign tumor of the apocrine gland usually found on the labia majora or the interlabial folds. It is benign tissue (not cancerous) but is often confused clinically with carcinoma of the vulva because of its tendency to ulcerate.

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.

Cementoblastoma, or benign cementoblastoma, is a relatively rare benign neoplasm of the cementum of the teeth. It is derived from ectomesenchyme of odontogenic origin. Less than 0.69%–8% of all odontogenic tumors.

PSN are benign. Once removed, they do not require any treatment and do not recur.

Lymphangiomatosis (LYMF) is a condition where a lymphangioma is not present in a single localised mass, but in a widespread or multifocal manner. It is a rare type of tumor which results from an abnormal development of the lymphatic system.

It is thought to be the result of congenital errors of lymphatic development occurring prior to the 20th week of gestation. Lymphangiomatosis is a condition marked by the presence of cysts that result from an increase both in the size and number of thin-walled lymphatic channels that are abnormally interconnected and dilated. 75% of cases involve multiple organs. It typically presents by age 20 and, although it is technically benign, these deranged lymphatics tend to invade surrounding tissues and cause problems due to invasion and/or compression of adjacent structures. The condition is most common in the bones and lungs and shares some characteristics with Gorham’s disease. Up to 75% of patients with lymphangiomatosis have bone involvement, leading some to conclude that lymphangiomatosis and Gorham’s disease should be considered as a spectrum of disease rather than separate diseases. When it occurs in the lungs, lymphangiomatosis has serious consequences and is most aggressive in the youngest children. When the condition extends into the chest it commonly results in the accumulation of chyle in the linings of the heart and/or lungs.

Chyle is composed of lymph fluid and fats that are absorbed from the small intestine by specialized lymphatic vessels called lacteals during digestion. The accumulations are described based on location: chylothorax is chyle in the chest; chylopericardium is chyle trapped inside the sack surrounding the heart; chyloascites is chyle trapped in the linings of the abdomen and abdominal organs. The presence of chyle in these places accounts for many of the symptoms and complications associated with both lymphangiomatosis and Gorham’s disease. The incidence of lymphangiomatosis is unknown and it is often misdiagnosed. It is separate and distinct from lymphangiectasis, lymphangioleiomyomatosis (LAM), pulmonary capillary hemangiomatosis, Kaposi’s sarcoma, and kaposiform hemangioendothelioma. Its unusual nature makes lymphangiomatosis (and Gorham’s disease) a diagnostic and therapeutic challenge. A multidisciplinary approach is generally necessary for optimal diagnosis and symptom management. The term literally means lymphatic system (lymph) vessel (angi) tumor or cyst (oma) condition (tosis).

Polypoid lesions of the gallbladder affect approximately 5% of the adult population. The causes are uncertain, but there is a definite correlation with increasing age and the presence of gallstones (cholelithiasis). Most affected individuals do not have symptoms. The gallbladder polyps are detected during abdominal ultrasonography performed for other reasons.

The incidence of gallbladder polyps is higher among men than women. The overall prevalence among men of Chinese ancestry is 9.5%, higher than other ethnic types.

Dermatofibromas are hard solitary slow-growing papules (rounded bumps) that may appear in a variety of colours, usually brownish to tan; they are often elevated or pedunculated. A dermatofibroma is associated with the dimple sign; by applying lateral pressure, there is a central depression of the dermatofibroma. Although typical dermatofibromas cause little or no discomfort, itching and tenderness can occur. Dermatofibromas can be found anywhere on the body, but most often they are found on the legs and arms. They occur most often in women; the male to female ratio is about 1:4. The age group in which they most commonly occur is 20 to 45 years.

Some physicians and researchers believe dermatofibromas form as a reaction to previous injuries such as insect bites or thorn pricks. They are composed of disordered collagen laid down by fibroblasts. Dermatofibromas are classed as benign skin lesions, meaning they are completely harmless, though they may be confused with a variety of subcutaneous tumours. Deep penetrating dermatofibromas may be difficult to distinguish, even histologically, from rare malignant fibrohistocytic tumours like dermatofibrosarcoma protuberans.

Dermatofibromas typically have a positive "buttonhole sign", or central dimpling in the center.

Benign fibromas may, but need not be, removed. Removal is usually a brief outpatient procedure.

Inflammatory fibroid polyp, abbreviated IFP, is a benign abnormal growth of tissue projecting into the lumen of the gastrointestinal tract.

The cause of lymphangiomatosis is not yet known. As stated earlier, it is generally considered to be the result of congenital errors of lymphatic development occurring prior to the 20th week of gestation. However, the root causes of these conditions remains unknown and further research is necessary.

Fibromas (or fibroid tumors or fibroids) are benign tumors that are composed of fibrous or connective tissue. They can grow in all organs, arising from mesenchyme tissue. The term "fibroblastic" or "fibromatous" is used to describe tumors of the fibrous connective tissue. When the term "fibroma" is used without modifier, it is usually considered benign, with the term fibrosarcoma reserved for malignant tumors.

Surgical excision of the lesion is done, and depending upon the clinical circumstances, this may or may not involve removal of the involved tooth. With incomplete removal, recurrence is common; some surgeons advocate curettage after extraction of teeth to decrease the overall rate of recurrence.

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.

Benign lymphoepithelial lesion is a type of benign enlargement of the parotid and/or lacrimal glands. This pathologic state is sometimes, but not always, associated with Sjögren's syndrome.

Spitz nevi are uncommon. Their annual incidence was estimated in a coastal population of sub-tropical Queensland to be 1.4 cases per 100,000 people. For comparison, the annual incidence of melanoma in the same population, which is high by world standards is 25.4 cases per 100,000 people.

Although they are most commonly found on people in their first two decades of life, the age range for people with Spitz nevi is from 6 months to 71 years, with a mean age of 22 years and a median age of 19 years.

Lipoblastoma is a type of subcutaneous benign fatty tumor.

Types include:

- Benign lipoblastomatosis, a tumor, also known as an embryonic lipoma, which usually occurs in children under three years old. This is the tumor of brown fat cells.

- Myxoid lipoblastoma, a cutaneous condition characterized by excess mucin

Intravenous leiomyomatosis is a rare condition seen exclusively in women in which leiomyomata, benign smooth muscle tumors, are found in veins. The masses are benign-appearing but can spread throughout the venous system leaving the uterus and even cause death when growing into the heart from the IVC. While the possibility that these arose de novo from the smooth muscle in the blood vessel wall was considered, chromosomal analysis suggests a uterine origin. Intravenous leiomyomata are usually but not always associated with uterine fibroids, and tend to recur.

This condition is related to benign metastasizing leiomyoma, in which the masses appear in more distant locations such as the lung and lymph nodes.

Mesenchymal neoplasms of the gallbladder are rare and in particular leiomyomas of the gallbladder have been rarely reported, all of them in patients with immune system disorders. Although, recently, a case was reported in absence of associated immunodeficiency at Monash Hospital in Melbourne Australia in a healthy 39-year-old woman with no symptoms.

In 80% of cases, the parotid gland is affected. Lacrimal glands are also affected.