A variety of lesions, some malignant, can manifest as masses in the neck, presenting real diagnostic challenges. Clinicians must understand the embryologic development of the head and neck and be familiar with the most recent diagnostic techniques. Objectives After completing this article, readers should be able to: 1. Know the differential diagnosis of the pediatric neck mass. 2. Understand how to conduct an evaluation of the pediatric neck mass. The broad differential diagnosis of pediatric neck masses typically fits into two main categories: congenital and acquired. Appreciation of the head and neck formation can simplify and greatly assist in identification of the underlying condition. We first review the embryonic formation as it relates to head and neck pathology, followed by key points of history and physical examination. The differential diagnostic possibilities are separated into categories of congenital and acquired neck masses. Finally, diagnostic clues and evaluation options are discussed. Formation of the Head and Neck The head and neck are derived from the branchial apparatus, an anatomically distinct structure that undergoes a complex formative process involving generation and resorption. Appreciating some aspects of the degeneration process helps explain the relationship between anatomic structures as well as the actual formation process. By the fourth week of gestation, the individual branchial arches initially become visible. Each arch has its own group of uniquely designated tissue types. For simplification, arch structures will be referred to as a numbered arch without differentiation of clefts, pouches, or other structures. The six paired branchial arches forming the branchial apparatus have ectodermal, mesodermal, and endodermal components, each with its own unique designations and components as listed in Table 1. Branchial arches are numbered based on their appearance and resulting structure across many species. In humans, the fifth arch regresses rapidly or does not form, and thus generally is omitted from discussion. Each arch has an artery and nerve associated with it. As the arch develops its own characteristic structures, the overall formation of the head is enabled by rapid proliferation of the second arch. This process results in the branchial apparatus folding on itself toward the area of the fifth arch, enclosing the internal aspects in the cervical sinus of His. The structures form and fuse together, resulting in the fetal neck. The relation of these components and their final resulting structures helps to conceptualize and categorize congenital neck masses and to add understanding of the relation and spread of inflammatory and neoplastic lesions. Figure 1 illustrates prominent anatomic features of the head and neck, as well as final distribution of the branchial arch structures. The development process explains how primary neck masses can Abbreviations CRP: C-reactive protein CT: computed tomography ESR: erythrocyte sedimentation rate FNA: fine needle aspiration MRI: magnetic res...
Figure I. Photographs show the left subglottic cyst pre-(A) and intraoperatively (B). Case report A lO-day-old boy, born full term via caesarean section and weighing 7 lb 11 OZ, was discharged home with no complic ations. At home , his mother noticed that the infant' s breathing had become progressively more congested. She sought medic al advice from a pedi atrici an. At the first visit, the boy' s abnormal breathing was attribut ed to a common cold. But despite conserva tive treatment, his
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