Fig. 3.8. Candidal hyphae penetrating the superficial layers (PAS/ D stain)

Oral infections with candidal organisms are very common. The most frequent organism is Candida albicans, a yeast-like fungus [150]. It can cause acute and chronic white lesions and atrophic, red lesions. Candidal spores are present as commensal organisms in the mouths of as many as 70% of individuals. The infective phase of the organism is characterised by the presence of hyphae that can directly invade oral keratinocytes [31]. A wide variety of factors predispose to infection by candidal organisms, particularly depressed cellular immunity and inhibition of the normal oral flora by broad spectrum antibiotics.

Fig. 3.8. Candidal hyphae penetrating the superficial layers (PAS/ D stain)

Thrush, or acute hyperplastic candidosis, is seen most commonly in neonates whose immune systems are still developing and in debilitated patients at the extremes of life. It is also a feature of patients with xerostomia due to irradiation, Sjögren syndrome and a wide variety of medications, particularly the tricyclic antidepressants. In addition, it is now increasingly becoming a feature of immunosuppressed individuals. Other factors predisposing to the development of thrush include iron deficiency anaemia, broad spectrum antibiotics and steroid inhalers used for the control of asthma. It is characterised clinically by the formation of soft, creamy-white, friable plaques that can be easily wiped off to leave underlying erythematous areas of mucosa. The soft palate and areas protected from friction such as the vestibular reflections are the most common sites.

Microscopically, the characteristic plaque of thrush is due to invasion of the superficial epithelial layers by candidal hyphae and the subsequent proliferative epithelial response (Fig 3.8) [26]. The surface epithelium is parakeratinised, oedematous and infiltrated by numerous neutrophils. Candidal hyphae penetrate the epithelium vertically and extend downwards as far as the gly-cogen-rich layer. The hyphae may be inconspicuous in H&E sections unless the microscope condenser is lowered to increase their refractility, but they can be readily visualised with periodic acid Schiff or Grocott's silver stains. The epithelium may show hyperplastic but attenuated rete processes and there is variable but occasionally florid acute inflammation of the underlying corium.

Denture-induced stomatitis is a variant of atrophic candidosis. It is typically seen in the hard palate beneath a full or partial dental prosthesis, particularly one constructed from acrylic. There is a sharply demarcated area of bright red, often boggy erythema limited by the extent of the denture. Occasionally there may be a few flecks of thrush, but typically there is no plaque formation. Although sometimes referred to as "denture sore mouth" the condition rarely causes any symptoms un less it is associated with angular stomatitis. Microscopy shows intercellular oedema and chronic inflammatory infiltration of the corium. Candidal organisms may not be seen in biopsy specimens, as the fungus tends to proliferate within the microscopic interstices of the denture material.

Generalised mucosal erythema, often with depapil-lation of the filiform lingual papillae, can also be a feature of both broad-spectrum antibiotic use and HIV infection.

Candidal lesions may present as persistent, adherent, firm white plaques that may be solitary or multiple, particularly in mucocutaneous candidosis syndromes [30]. In the latter, the mouth is often the most severely affected site. These lesions are referred to as chronic hyperplastic candidosis or candidal leukoplakia. Most patients with isolated plaques are men of middle age or older and the majority smoke cigarettes. The most common sites of involvement are the dorsum of the tongue and the post-commissural buccal mucosa. The plaques are often thick with a rough, irregular surface that may be nodular. In many cases the lesion forms a variegated red and white patch producing a speckled appearance.

Microscopy shows a parakeratinised surface infiltrated by neutrophils forming spongiform pustules. The epithelium shows downgrowths of blunt or club-shaped rete ridges with thinning of the suprapapillary areas to produce a psoriasiform appearance. The BMZ may be thickened and prominent and there is variable but often severe inflammation in the underlying corium. In some cases there can be conspicuous peri-capillary fibrinous exudation, particularly in the papillary corium. Candi-dal hyphae may be remarkably sparse and not detected unless multiple sections and special stains are used. Electron microscopy shows that the hyphae are intracellular parasites that grow within the cytoplasm of the epithelial cells rather than along the intercellular spaces.

How To Deal With Rosacea and Eczema

How To Deal With Rosacea and Eczema

Rosacea and Eczema are two skin conditions that are fairly commonly found throughout the world. Each of them is characterized by different features, and can be both discomfiting as well as result in undesirable appearance features. In a nutshell, theyre problems that many would want to deal with.

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