The Child With a Neck Mass

Solid Neck Masses

The remainder of this manuscript will focus on benign and malignant extra thyroid solid neck masses in children, including fibromatosis colli, inflammatory adenopathy, hemangioma, neurofibroma, teratoma, lymphoma, rhabdomyosarcoma, neuroblastoma, and metastatic adenopathy.

Fibromatosis colli or sternocleidomastoid tumor of infancy occurs in neonates. The etiology is uncertain but may be related to intramuscular hemorrhage or fibrosis. There is an increased risk in neonates with a history of breech presentation and/or difficult delivery. Patients typically present at 2 to 4 weeks of age with a unilateral neck mass, with or without torticollis. Ultrasound is the imaging modality of choice, showing focal or diffuse enlargement of the sternocleidomastoid muscle (SCM), which may be homogeneous or heterogeneous in echotexture (Figure 13). There may be a rim of decreased echoes thought to represent compressed normal adjacent sternocleidomastoid muscle.^[2,3,24]

Nonsuppurative adenitis is the most common non-neoplastic solid neck mass in children. The majority of children with uncomplicated cervical adenitis are treated medically and do not require imaging. If they are toxic-appearing or have symptoms that increase despite administration of antibiotic therapy, postcontrast CT imaging is frequently performed to assess the extent of the inflammatory process and rule out a focal abscess. When imaging children with cervical adenitis, the key questions to be answered are location of abscess, extent of cellulitis and myositis, and evaluation of the vascular structures of the neck to exclude jugular vein compression or thrombosis as well as narrowing of the internal carotid artery.^[25] Lymphadenitis may be secondary to viral disease, bacterial disease, mycobacterial disease, or fungal disease. Nonsuppurative inflammatory adenitis has a typical appearance on all imaging modalities showing multiple (sometimes conglomerate) nodes. Hilar flow is demonstrated on US. Nontuberculous mycobacterial disease may lack evidence of surrounding cellulitis and myositis and may contain small calcifications or low-attenuation centers (Figure 14).^[26,27,28] Cat-scratch disease is not uncommon in children and may also present with cervical adenopathy, without significant associated cellulitis (Figure 15). This diagnosis should be considered in any child with a history of exposure to cats. If a child without evidence of cellulitis presents with significant cervical adenopathy and associated enlargement of the palatine and adenoid tonsils, mononucleosis should be considered (Figure 16). A well-defined or irregularly shaped fluid collection with an enhancing rim is certainly suggestive of an abscess (Figure 17). However, these imaging characteristics are not 100% specific, and the appearance of phlegmon without true drainable pus can be similar.^[29]

Hemangioma of infancy is a benign neoplasm resulting from endothelial proliferation, which usually presents in children less than 6 months of age, gradually increases over the next 2 years, and spontaneously involutes over the next 5 to 7 years. In the proliferative phase, they demonstrate diffuse intense contrast enhancement (Figure 18). High-flow intralesional flow voids will be demonstrated on MRI (Figure 19). During the involutional phase, they show evidence of fatty infiltration and decrease in size.^[30,31] Attention to the age of the patient with a significantly enhancing neck mass is extremely important. In an older child without a prior history of a neck mass in infancy, similar imaging characteristics should raise the question of sarcoma rather than of benign hemangioma. Treatment of hemangioma occurring in an infant is usually expectant waiting. Steroids, interferon, and, rarely, surgery are reserved for lesions that compromise the airway or are associated with significant loss of skin integrity.

Neurofibromas are unencapsulated benign nerve sheath tumors of Schwann cell origin. They may be single or multiple; when multiple or plexiform, they almost always occur in children with neurofibromatosis Type 1. Solitary lesions may be very well defined; plexiform lesions are ill defined and infiltrative. Frequently, neurofibromas will show variable contrast enhancement, with or without a "target sign" composed of a central area of decreased T2 signal intensity and decreased contrast enhancement (Figure 20).^[32]

Teratomas are neoplasms composed of multiple tissues that are foreign to the part of the body in which the lesion arises.^[33] Teratomas in children are most commonly sacrococcygeal, and 5% to 14% occur in the head and neck region; most of these children are less than 1 year of age at the time of diagnosis. These lesions contain all 3 germ layers, originate from pleuripotential cells, and may be composed of mature or immature elements. In the neonate, the presence of immature elements does not correlate with malignant potential, and most teratomas are benign. Most are very large and complex lesions containing solid and cystic components, frequently with fat and calcification (Figure 21). Treatment is surgical excision.

Appl Radiol. 2005;34(8):8-22. © 2005 Anderson Publishing, Ltd.

Cite this: The Child With a Neck Mass - Medscape - Aug 01, 2005.