Larynx and related structures

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The supraglottic and glottic regions are frequently inflamed in acute pharyngitis

Viral and bacterial infections of the pharynx frequently involve the supraglottic and glottic regions, producing hoarseness and temporary voice loss. Infection usually extends into subglottic and tracheal regions, and perhaps down into bronchi, producing cough and tracheal soreness. This symptom complex, which is known as upper respiratory tract infection (URTI), is very common but usually transient and trivial. It can have serious consequences in young children and in the elderly or debilitated.

In young children the small airway can become obstructed by mucosal and sub-mucosal swelling (croup). Acute epiglottitis, usually due to Haemophilus influenzae infection, can produce fatal obstruction.

In the elderly and debilitated the cough reflex is poor, and infected material cannot be cleared from the tracheobronchial tree. It may pass into small peripheral bronchi and bronchioles under the influence of gravity, producing bronchopneumonia.
Other infective causes of laryngitis are now rare

Diphtheria is now an uncommon cause of laryngitis. Formerly the disease was frequently fatal because of the production of a thick, fibrinous membrane across the airway, leading to asphyxia.

Tuberculosis affecting the larynx usually resulted in the coughing up of tuberculous sputum from a cavitating apical abscess in adults with open pulmonary TB.

Inflammatory changes in the larynx may also result from allergic and toxic damage

Allergic pharyngolaryngeal oedema can arise as a life-threatening Type 1 hypersensitivity reaction, which is usually associated with swelling of the face (angioneurotic oedema). Bronchospasm may also occur as part of the same reaction, increasing the severity of the asphyxia.

Acute toxic laryngitis is rare, but is occasionally seen following the inhalation of toxic fumes during exposure in a fire (inhalation of fumes from polystyrene material being particularly important) although the direct physical effect of heat may also be responsible. Industrial exposure to toxic fumes is also an important cause.

Chronic laryngitis is most commonly seen in heavy cigarette smokers. Chronic inflammatory infiltrates are present in the larynx, and there may be thinning or keratotic thickening of the overlying epidermis. In the latter pattern, dysplastic change may occur in the basal layer. This is considered to be a predisposing factor in the eventual development of squamous carcinoma.

Laryngeal tumours

Benign thickenings, nodules and polyps of the larynx are a common cause of hoarseness

Chronic laryngitis may lead to permanent thickening of the laryngeal mucosa and submucosa, particularly where there is associated excess production of keratin (smoker's keratosis).
So-called singer's nodes are smooth, round, minute nodules located at the nodal point at the junction between the anterior third and posterior two-thirds of the vocal cords. Particularly seen in singers and professional voice users, they are covered by smooth epithelium, and the submucosa shows fibrosis.

Diffuse inflammatory oedema (sometimes polypoid)} is the result of an unusual pattern of oedema (Reinke's oedema) with hyaline change and occasional stromal haemorrhage. Histologically there is marked fibrinoid degeneration of the stroma. Excessive bleeding may lead to haematoma formation, particularly after strenuous vocal activity.

Laryngeal cysts occur most commonly in the aryepiglottic folds, rather than on the true vocal cords. These translucent structures, which are filled with thick mucus, are retention cysts resulting from blockage of the ducts of mucus glands.

Warty papillomas on the larynx are usually due to infection by the human papilloma virus (HPV 11 and 16)

In adults warty papilloma is usually solitary and confined to the vocal cords; its viral nature is less obvious than those in children. Clinically it may be difficult to distinguish from an early verrucous carcinoma, and there are also histological similarities.

As the name suggests, juvenile laryngeal papillomatosis is largely confined to children. It consists of multiple, soft, pink papillomas on the vocal cord, also extending into other parts of the larynx, sometimes even down the trachea. These lesions have the histological features of a florid viral wart. They are difficult to eradicate, often requiring repeat multiple excisions, since they are typically both persistent and recurrent. 

Carcinoma of the larynx is an important malignancy in cigarette smokers 

Carcinoma of the larynx is most common in male cigarette smokers over the age of 40 years, but is becoming increasingly common in women smokers. It is a squamous carcinoma and can occur in the supraglottic region, e.g. the aryepiglottic folds, false cords and ventricles; the glottic region, in the true vocal cords and anterior and posterior commissures; or the subglottic region, arising below the true vocal cords and above the first tracheal ring.

Tumours of the true vocal cords (glottic) are most common. They have the best prognosis if detected early (an early symptom being hoarseness), because the true vocal cords have a poor lymphatic drainage except at the commissures. The tumour remains localized to the larynx for a long time and, except in neglected tumours that have invaded local tissues widely, metastasis to lymph nodes is rare.

Supraglottic tumours can be resected with sparing of the true vocal cords. However, as these areas are better supplied with lymphatics, lymph node metastasis is more common than in glottic tumours, and may be the presenting symptom.

Subglottic tumours are the rarest type, and have a poor prognosis because of late presentation; symptoms are often manifest only when extensive growth and local spread lead to stridor and voice loss due to vocal cord involvement.

Some invasive squamous carcinomas of the larynx arise in areas of severe dysplasia and carcinoma in situ

Mild dysplasia of the laryngeal epithelium is a common feature of smoker's keratosis, the chronic hyperkeratotic laryngeal thickening that occurs in heavy smokers. More extensive and severe dysplasia merges with carcinoma in situ, and there may be small foci suggesting microinvasion. There is some dispute as to the proportion of invasive squamous carcinomas that arise in pre-existing areas of carcinoma in situ, but common sense seems to suggest that, as in the colon and other sites, there is a sequence in the larynx of mild dysplasia, through moderate dysplasia, severe dysplasia and carcinoma in situ, culminating in invasive carcinoma.

Most invasive squamous carcinomas are well-differentiated keratinizing squamous carcinomas but, occasionally, poorly differentiated forms occur, which are sometimes spindle-celled. An important variant is verrucous carcinoma, which usually affects one or both of the true vocal cords. Clinically it presents as an often large, warty papillary tumour, with all the clinical features of malignancy. However, histologically it appears very bland, being composed of benign-looking squamous epithelium with hyperkeratosis. Despite the innocent histology, these tumours are locally destructive and require surgical removal to prevent fatal obstruction or laryngeal destruction. Metastasis is virtually unknown, but occasionally follows attempts at radiotherapy treatment.
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Revised: 02-11-2014.