Familiarity with regional anatomy helps to narrow the differential diagnosis in a child who presents with a neck mass. Because most neck masses in infants and children are enlarged lymph nodes, it is important to be familiar with areas of lymphatic drainage. In addition, certain masses present in typical locations that help to identify the cause. The neck is divided into the anterior and posterior triangles, with the sternocleidomastoid muscle (SCM) forming the posterior border of the anterior triangle (Figure 54-1).

It is important to distinguish adenopathy from adenitis. Adenopathy is defined by nodal enlargement. In adenitis, the swelling is usually accompanied by signs of inflammation such as warmth, tenderness, and erythema. The vast majority of children with adenopathy have a benign viral or easily treatable bacterial cause. However, follow-up is important to assess resolution of symptoms and progressive reduction in size so as not to miss unusual infectious, inflammatory, or oncological processes. Moreover, any node >2 cm in diameter warrants further attention, as it falls outside the range of benign hyperplasia. A more detailed review of this topic is covered in Chapter 50, “Lymphadenopathy.”

Lemierre’s syndrome (also known as necrobacillosis or postanginal sepsis) is a rare disease characterized by sepsis secondary to an anaerobic infection of the tonsillar or peritonsillar region and superficial thrombophlebitis of the internal jugular vein. It typically presents with prolonged pharyngitis or tonsillitis followed by lateral neck pain, swelling, and subsequent pulmonary symptoms. The most common bacteria isolated is Fusobacterium necrophorum. The key to diagnosis is having appropriate index of suspicion and confirmation by ultrasound, computed tomography (CT), or MRI demonstrating phlebitis of the internal jugular vein. Management consists of appropriate antibiotics and possible anticoagulation.