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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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