Benign Neoplasms of the Neck (Soft Tissue, Bone, and Lymph Node)

Clinical Features

Approximately two-thirds of lymphangiomas are noted shortly after birth, and 95% are present by the end of the second year of life. Cystic hygroma may also be detected in utero with ultrasonography. Cystic hygroma may be associated with fetal hydrops and several genetic abnormalities, most notably Turner syndrome ( Fig. 21.1 ) but also Noonan syndrome and trisomies 13, 18, and 21. In general, symptoms are related to pressure caused by the slowly enlarging mass or extension of the mass into the posterior neck or, less commonly, into the anterior compartment, cheek, mediastinum, or axilla. When the hygroma is located superior to the hyoid bone, it may cause dysphagia or airway compression. Ultrasound will show a cystic lesion, frequently identified prenatally, while computed tomography (CT) studies will show a nonenhancing multilocular cystic mass.

Cavernous lymphangioma forms an ill-defined, spongy, compressible mass and is found most commonly in the tongue, cheek, floor of mouth, and lips; it is uncommon in the soft tissues. In contrast, capillary lymphangioma is usually confined to the skin and is clinically the least significant of the three types.

Pathologic Features

Cystic lymphangiomas (hygromas) vary from a single soft mass with a pseudocontour to lobulated multicystic masses ( Fig. 21.1 ). They contain clear to white-turbid fluid, described as milk-like ( Fig. 21.1 ). Histologically, they consist of dilated, thin-walled spaces filled with eosinophilic, proteinaceous fluid and lined by flat endothelial cells ( Fig. 21.2 ). The intervening stroma contains scattered lymphoid aggregates and wisps of smooth muscle fibers ( Fig. 21.3 ). Fibrosis may be increased in lesions that have been present for a long time.

Ancillary Studies

Endothelial markers (factor VIII–related antigen [FVIII-RAg], CD31, CD34, and Ulex europaeus ) can be expressed by endothelial cells in both hemangiomas and lymphangiomas. D2-40 (podoplanin) may be a lymphatic-specific marker, along with CD9 and lymphatic vessel endothelial receptor 1 (LYVE-1), although podoplanin may be easier to interpret.

Differential Diagnosis

The most common differential diagnosis is with cavernous hemangioma. Lymphangioma contains proteinaceous fluid and the surrounding tissues are usually infiltrated by lymphocytes, whereas cavernous hemangiomas are filled with red blood cells and lack valve structures. Metastatic papillary thyroid carcinoma may have flattened cells along the spaces, but TTF1 and/or thyroglobulin will be positive. Furthermore, a lymph node architecture should be recognizable, often at the periphery.

Prognosis and Therapy

Mortality rates are between 3% and 7%, specifically related to pressure destruction of vital structures of the neck. Lymphangiomas may occasionally become infected and may cause difficulty swallowing or respiratory distress. Surgery is the treatment of choice, while laser treatment or injected sclerosing agents (such as bleomycin) are alternative therapies. Recurrence rates range from 15% to 50% and are highest when the lymphangioma is incompletely removed. Malignant transformation is not documented.

Clinical Features

More than 90% of cervical teratomas occur in neonates or infants and are rare in patients older than 1 year. They occur with similar frequency in boys and girls. In addition to a neck mass, severe respiratory distress is notable in neonates, frequently leading to airway compromise and requiring immediate surgery. Polyhydramnios and other malformations may be seen in approximately 20% of patients, many of whom will show an elevated α-fetoprotein concentration in amniotic fluid. Failure of midline structure development may result in fetal demise, even though the lesion is histologically benign. If detected prenatally by ultrasonographic examination, surgical planning may yield a better outcome. CT or magnetic resonance imaging (MRI) usually shows a multilocular mass ( Fig. 21.4 ). Cervical teratomas in adults are extremely rare, with patients reporting a rapidly enlarging neck mass.