Page 1 - 64 head&neck36-40_opt

CHAPTER 36

Neck: Cysts, Sinuses, and Fistulas

James O. Adeniran
Kokila Lakhoo

Introduction Table 36.1: Common causes of lumps in the necks of children
Lumps in the neck are a common problem in children. Some of the Location Cause
lumps may not be obvious at birth but slowly get bigger and become Lateral side of neck Lymph nodes due to scalp or throat infections, tubercu-
worrying to the parents. Most of the lumps are asymptomatic, but losis, or lymphomas
some can cause respiratory or swallowing difficulties. Some lumps Cystic hygromas
1,2
become infected and require urgent medical attention. Most sinuses are Sternomastoid tumour
usually not noticed at birth, but as the child grows, there is persistent Teratomas
discharge from the ostia. Many of these lumps and sinuses are rem- Thyroid masses
nants of structures that form the face and neck. Some sinuses are due Branchial cyst—first, second, third, fourth
to chronic infections. Midline of neck Thyroglossal cysts
Lumps that appear around the necks of children may be due to various Dermoids
conditions, as listed in Table 36.1. This chapter focuses on cysts, sinuses, and Haemangiomas
fistulas of the neck, which are remnants of branchial apparatus, and remnants Ectopic thyroid tissue
of the thyroid gland. Sinuses due to tuberculosis, human immunodeficiency
virus (HIV), and fungi also are discussed. Lymphadenopathy is discussed
in Chapter 37, sternomastoid tumours in Chapter 38, thyroid masses in
Chapter 40, and lymphangiomas in Chapter 44.
Branchial Arches, Clefts, and Pouches
Embryology and Pathology
Branchial arches appear as four pairs of ridges on the lateral side
of the face of the 5-week old embryo (Figures 36.1 and 36.2). The
arches bulge into the side walls of the foregut and meet each other in
its floor, displacing the heart caudally to establish the neck region of the
3
embryo. The ridges are separated by four pairs of external, ectodermal
grooves (branchial clefts) matched internally by four pharyngeal, endo-
dermal pouches. The arches form the skeleton, musculature, and blood
vessels of the jaws, palate, larynx, and pharynx, as well as the muscles
of the face. As the dorsal ends of each arch approach the hindbrain,
these structures are invaded by nerve fibres from the branchial efferent
column. The ventral ends of the arches also converge on the pericar-
dium to connect capillaries from the truncus arteriosus. Each arch has Source: FitzGerald MJT. Human Embryology: A Regional Approach. Harper & Row Publishers,
3
1978. Used by permission.
mesenchyme, which develops into bone, cartilage, blood vessels, and
muscles innervated by the nerve of that arch. Figure 36.1: Five-week embryo showing the position of
branchial arches.
First Branchial Arch
Embryology Differentiation of the first branchial arch is shown below:
The first, or mandibular, arch appears on the 22nd gestational day, and • Skin: skin of lower part of face
by the 6th week fuses in the midline to form the mesenchymal primor-
• Bones: malleus, incus, mandible, maxilla
dium that develops into the anterior two-thirds of the tongue. The core
of the arch chondrifies to form Meckel’s cartilage, which develops • Muscles: muscles of mastication, floor of the mouth, tensor palati,
into the malleus and incus bones. The muscles of mastication develop tensor tympani, anterior belly digastric and mylohyoid
from the first arch mesoderm, all innervated by the motor root of the
• Nerve: mandibular branch of trigeminal nerve
trigeminal. The first branchial cleft forms the external acoustic meatus.
The first pharyngeal pouch is recognised after the formation of the • Artery: maxillary
head fold about the 20th day of embryonic life. The first pair of grooves
• Membrane: mucous membrane of nasopharynx
and pouches persists to form the auditory canal and eustachian tube,
which is separated by the tympanic membrane. The first pouch and Remnants
membrane persist as the pharyngotympanic tube, middle ear cavity, and Abnormal development of the first branchial arch results in cleft lip and
tympanic membrane. palate, pinna deformities, and malformed malleus and incus, which may
produce congenital deafness. 3–5