Page 549 - Textbook of Pathology, 6th Edition

SALIVARY GLANDS 533

NORMAL STRUCTURE

There are two main groups of salivary glands—major and
minor. The major salivary glands are the three paired glands:
parotid, submandibular and sublingual. The minor salivary
glands are numerous and are widely distributed in the
mucosa of oral cavity. The main duct of the parotid gland
drains into the oral cavity opposite the second maxillary
molar, while the ducts of submandibular and sublingual
glands empty in the floor of the mouth. At times, heterotopic
salivary gland tissue may be present in lymph nodes near or
within the parotid gland.
Histologically, the salivary glands are tubuloalveolar glands
and may contain mucous cells, serous cells, or both. The
parotid gland is purely serous. The submandibular gland is
mixed type but is predominantly serous, whereas the
sublingual gland though also a mixed gland is predominantly
mucous type. Similarly, minor salivary glands may also be
serous, mucous or mixed type. Figure 19.12 Lesions in mumps.
The secretory acini of the major salivary glands are
drained by ducts lined by: atrophy. Less commonly, cytomegalovirus infection may
low cuboidal epithelium in the intercalated portion, occur in parotid glands of infants and young children.
tall columnar epithelium in the intralobular ducts, and 2. Bacterial and mycotic infections. Bacterial infections may CHAPTER 19
simpler epithelium in the secretory ducts. cause acute sialadenitis more often. Sometimes there are
recurrent attacks of acute parotitis when parotitis becomes
The product of major salivary glands is saliva which
performs various functions such as lubrication for swallow- chronic.
ing and speech, and has enzyme amylase and antibacterial i) Acute sialadenitis: The causes are as follows:
properties too. a) Acute infectious fevers
b) Acute postoperative parotitis (ascent of microorganisms
SALIVARY FLOW DISTURBANCES up the parotid duct from the mouth)
SIALORRHOEA (PTYALISM). Increased flow of saliva is c) General debility
termed sialorrhoea or ptyalism. It occurs commonly due to: d) Old age
stomatitis, teething, mentally retarded state, schizophrenia, e) Dehydration.
neurological disturbances, increased gastric secretion and ii) Chronic sialadenitis. This may result from the following
sialosis (i.e. uniform, symmetric, painless hypertrophy of causes: The Oral Cavity and Salivary Glands
salivary glands). a) Recurrent obstructive type. Recurrent obstruction due to
calculi (sialolithiasis), stricture, surgery, injury etc. may cause
XEROSTOMIA. Decreased salivary flow is termed xero-
stomia. It is associated with the following conditions: repeated attacks of acute sialadenitis by ascending infection
Sjögren’s syndrome, sarcoidosis, mumps parotitis, Mikulicz’s and then chronicity.
syndrome, megaloblastic anaemia, dehydration, drug intake b) Recurrent non-obstructive type. Recurrent mild ascending
(e.g. antihistamines, antihypertensives, antidepressants). infection of the parotid gland may occur due to non-
obstructive causes which reduce salivary secretion like due
to intake of drugs causing hyposalivation (e.g. antihista-
SIALADENITIS
mines, antihypertensives, antidepressants), effect of
Inflammation of salivary glands, sialadenitis, may be acute irradiation and congenital malformations of the duct system.
or chronic; the latter being more common. c) Chronic inflammatory diseases. Tuberculosis, actinomycosis
and other mycoses may rarely occur in the salivary glands.
ETIOLOGY. Sialadenitis can occur due to the following
causes: 3. Autoimmune disease. Inflammatory changes are seen in
salivary glands in 2 autoimmune diseases:
1. Viral infections. The most common inflammatory lesion
of the salivary glands particularly of the parotid glands, is i) Sjögren’s syndrome characterised by triad of dry eyes
mumps occurring in children of school-age. It is characterised (keratoconjunctivitis sicca), dry mouth (xerostomia) and
by triad of pathological involvement—epidemic parotitis rheumatoid arthritis (Chapter 4).
(mumps), orchitis-oophoritis, and pancreatitis (Fig. 19.12). ii) Mikulicz’s syndrome is the combination of inflammatory
Involvement of the testis and pancreas may lead to their enlargement of salivary and lacrimal glands with xerostomia.