Pathology of the Head and Neck

Neck Cysts, Metastasis, Dissection Chapter 9 265Table 9.1. Order of frequency of cervical cystic tumours according to age (extracted from [52, 68, 70, 115]). CA carcinomaInfants and children Adolescents AdultsThyroglossal duct cystBranchial cleft cystLymphangiomaHaemangiomaTeratoma and dermoidBronchogenic cystThymic cystLaryngoceleMetastatic thyroid caThyroglossal duct cystBranchial cleft cystBronchogenic cystThymic cystTeratoma and dermoidMetastatic thyroid caMetastatic cystic caThyroglossal duct cystCervical ranulaBranchial cleft cystLaryngoceleParathyroid cystThymic cystcal behaviour [26]. Because of the frequent similarities inthe morphological aspects of various cysts, a definitivediagnosis is dependent on clinical data. These include theexact location of the lesion and the age of the patient. Theclinical manifestations of cysts depend largely on theirsize. Most cysts in the early stages are asymptomatic andare found on routine physical or radiographic examination.Rupture and drainage leads to infection, abscess,and sinus formation, which are frequently accompaniedby pain and swelling. In certain instances, computed tomographyscan can be of benefit in establishing the diagnosisand/or extension into adjacent structures [59].Aspiration needle biopsy can also be useful in distinguishingbetween cysts and other pathoses that presenta similar roentgenographic appearance [41].In adults, an asymptomatic neck mass should be consideredmalignancy until proven otherwise. With the exceptionof thyroid nodules and salivary gland tumours,neck masses in adults have the following characteristics:80% of the masses are neoplastic, 80% of neoplasticmasses are malignant, 80% of malignancies are metastatic,and in 80%, the primary tumour is located abovethe level of clavicle [70]. In contrast, 90% of neck massesin children represent benign conditions. In a review of445 children with neck masses, 55% of the masses werecongenital cysts, 27% were inflammatory lesions, 11%were malignant and 7% were miscellaneous conditions[117]. Table 9.1 lists the causes of neck masses in orderof the frequency with which they occur, according to theage of the patient.9.3.1 Developmental Cysts9.3.1.1 Branchial Cleft Cysts,Sinuses and FistulaeBranchial apparatus anomalies are lateral cervical lesionsthat result from congenital developmental defectsarising from the primitive branchial arches, clefts andpouches.The branchial apparatus appears around the 4thweek of gestation and gives rise to multiple structures orderivatives of the ears, face, oral cavity and neck. Thesestructures are described in more detail in other sources[126]. Anatomically, the branchial apparatus consistsof a paired series of six arches, five internal pouchesand five external clefts or grooves. The external groovesare of ectodermal origin and are called branchial clefts.The internal pouches are of endodermal origin and areknown as pharyngeal pouches; they are separated bytheir branchial plates [126]. Each branchial arch is suppliedby an artery and a nerve and develops into well-definedmuscles, bone and cartilage. Thus, all three germcelllayers contribute to formation of the branchial apparatus.The arches are numbered 1–6, from cranial tocaudal, and the clefts and pouches 1–5. The correspondingcleft and pouch lie immediately caudal to their numericalarch, that is, the first cleft and pouch lie betweenthe first and second arches, the second cleft and pouchlie between the second and third arches, and so on.A number of theories exist to explain the genesis ofbranchial cleft anomalies. Regauer and associates haveproposed that the cysts arise from the endodermally derivedsecond branchial pouch [95]. An alternative explanationis that the cysts develop from cystic epithelial inclusionsin lymph nodes that are either of salivary glandorigin or from displaced epithelium from the palatinetonsil [43]. Golledge and Ellis recently reviewed the varioustheories on the histogenesis of branchial cleft cysts[43].Papers dealing with anomalies of the branchial apparatusdo not always distinguish between the terms sinusand fistula and often use them interchangeably as synonyms.A sinus is a tract that has only one opening, eithercutaneous or mucosal. A fistula is a tract that hastwo openings, one cutaneous and one mucosal. A cystmay occur independently or in association with a sinusor fistula.Most anomalies of the branchial apparatus of concernto the surgical pathologist present clinically as acyst, fistula, sinus or skin tag. Fistulae, sinuses and skintags occur in younger patients than cysts do [20]. Bran-