Head and neck lymph nodes in children: the spectrum from normal to abnormal.

Lymphadenopathy of the head and neck region is a common finding in children and a very common reason to image the craniocervical region. Enlarged lymph nodes are commonly palpated by the pediatrician in the office and commonly imaged by the pediatric radiologist. The difficult task of the clinician is to determine whether the adenopathy is acute (<3 weeks) or chronic (>6 weeks) and when imaging is indicated. In children, radiation is always a consideration when choosing an imaging modality; thus, US is usually the first imaging study at our institution, and CT the second option, usually reserved for the very ill child or for when there is a high index of suspicion for malignancy. We present the normal anatomy of head and neck lymph nodes and the US, CT, and MRI appearances in normal and pathologic states to help clinicians generate a reasonable differential diagnosis and prevent unnecessary procedures.