Ch05: Red and White Lesions of the Oral Mucosa

Red and White Lesions of the Oral Mucosa 95
A B
FIGURE 5-15 A, Patchy white plaque and flecks that rubbed off represent thrush. The patient complained of a burning mouth. B, More-extensive
pseudomembranous lesions associated with an erythematous base in an adult with severe thrush. (Courtesy of Dr. T.J. Johnson, University of Nebraska Medical
Center, College of Dentistry)
pearly white plaquelike lesions are relatively inconspicuous at
times. Any mucosal surface may be involved, and erythematous
or white areas often develop beneath partial or complete
dentures. The lesions may involve the entire oral mucosa (see
Figure 5-15, B) or may involve relatively localized areas where
normal cleansing mechanisms are poor.
A prodromal symptom of a rapid onset of a bad taste and
the loss of taste discrimination is described by some adults. A
burning sensation of the mouth and throat may also precede
the appearance of the white pseudomembranous lesions.
Symptoms of this type in a patient receiving broad-spectrum
antibiotics are strongly suggestive of thrush or other forms of
oral candidiasis. Patients with immunodeficiencies, such as
those suffering from AIDS or hematologic malignancies, are
also especially susceptible to this form of candidiasis.
The differential diagnosis of thrush includes food debris,
habitual cheek biting, and rarely, a genetically determined
epithelial abnormality such as white sponge nevus.
Causative Organism and Frequency. The yeastlike fungus
that causes thrush and other manifestations of candidiasis
occurs in both yeast and mycelial forms in the oral cavity. The
organism grows by a budding of the yeast cells to form germ
tubes and individual hyphal elements, which undergo limited
peripheral branching to form a pseudomycelium. These phenomena
can be demonstrated in smears and tissue sections
and form the basis for confirmatory laboratory diagnostic tests
for candidiasis.
Candida species are normal inhabitants of the oral flora of
many individuals, but are present in the mouth of the healthy
carrier in a low concentration of 200 to 500 cells per milliliter
of saliva. 100,101 At this concentration, the organism cannot
usually be identified by direct microscopic examination of
smears from the oral mucosa, and its presence can be demonstrated
only by inoculation onto a selective medium such as
Sabouraud agar. Saliva samples give a carrier rate of 20 to 30%
for healthy young adults whereas imprint cultures, which sample
colonized sites rather than detached cells and organisms in
the mixed saliva, give a figure as high as 44%. 102 Imprint cultures
suggest that the papillae of the posterior oral surface of
the tongue are the primary colonization site in the oral cavity
of healthy dentate carriers and that other areas are contaminated
or secondarily colonized from this site.
The asymptomatic carrier state is affected by a number of
known factors, including the immune status of the host, the
strain of Candida, the local oral environment, smoking, prior
use of antibiotics, and the general health of the host. The carrier
state is more prevalent in diabetic individuals, and the
density of Candida at various oral sites is also increased in
persons with diabetes. As reported by Guggenheimer and colleagues,
diabetic patients with clinical features of candidiasis
were more likely to have a longer duration of insulin-dependent
diabetes mellitus (IDDM), to have poorer glycemic control,
and to experience the complications of nephropathy and
retinopathy. 103 The wearing of removable prosthetic appliances
is also associated with higher asymptomatic carrier
prevalence rates. Importantly, simple measures to improve the
oral health of the patient will reduce the rate of Candida colonization
of the oral mucosa and denture. 104
Because Candida spp are normal oral inhabitants, thrush
and other forms of oral candidiasis may be classified as specific
endogenous infections. A variety of species of Candida have
been isolated from carriers and from patients with candidiasis.
Candida albicans, Candida tropicalis, and Candida glabrata
account for over 80% of medical isolates; Candida parapsilopsis,
Candida guilliermondii, Candida krusei, and Candida
pseudotropicalis are also recognized as pathogens. Candidiasis
in HIV-positive patients is often associated with a shift in
species, from Candida albicans to Candida glabrata and
Candida krusei. 105 The particular species involved with a given
oral infection is generally not thought to be of any significance,
but Candida albicans is most commonly found in
thrush, and several subtypes of this species have been implicated
as cocarcinogens in speckled leukoplakia. 96,97 Severity
and refractoriness of Candida infection to treatment possibly
depend more on the site of involvement and on predisposing