Pathology of the Head and Neck

Oral Cavity Chapter 3 81these do not affect the mouth. The titre of cANCA maybe related to the severity of the disease and therefore canbe a useful index of prognosis and efficacy of treatment.However, in patients with limited or protracted superficialforms of the disease, the ANCA may be negativefor months or even years so that other clinicopathologicalcriteria should not be ignored when making the diagnosis.3.3.8 TuberculosisOral tuberculosis is rare, but is important as it is usuallya complication of advanced open pulmonary disease[155]. Tuberculosis is becoming increasingly more commonin developed countries. This is partly due to HIVinfections and the fact that multiple drug-resistant mycobacteriaare becoming widespread.The typical lesion is an ulcer, most commonly on themid-dorsum of the tongue and gingiva, but other sitesmay be involved [122]. The ulcer usually has underminededges, which may be stellate, and a pale granularfloor. Occasionally it presents as a non-specific areaof erythema or a chronic fissure [112]. It is painless inits early stages, but may become painful later. There isusually no regional lymph node involvement. The clinicalfeatures are often entirely non-specific and the diagnosisis initially suspected when the microscopy showsmultiple epithelioid granulomas in the corium underlyingan ulcer with undermined margins. The granulomasare usually non-caseating and it is unusual to demonstrateMycobacteria, even using auramine and rhodaminestaining. The organisms may be detected in thesputum (but rarely in the oral lesion) and chest radiographstypically show advanced disease. In patients whoare immunosuppressed, the possibility of atypical mycobacterialinfection needs to be considered.3.4 White Lesions3.4.1 CandidosisOral infections with candidal organisms are very common.The most frequent organism is Candida albicans,a yeast-like fungus [150]. It can cause acute and chronicwhite lesions and atrophic, red lesions. Candidal sporesare present as commensal organisms in the mouths ofas many as 70% of individuals. The infective phase ofthe organism is characterised by the presence of hyphaethat can directly invade oral keratinocytes [31]. A widevariety of factors predispose to infection by candidal organisms,particularly depressed cellular immunity andinhibition of the normal oral flora by broad spectrumantibiotics.Fig. 3.8. Candidal hyphae penetrating the superficial layers (PAS/D stain)Thrush, or acute hyperplastic candidosis, is seenmost commonly in neonates whose immune systemsare still developing and in debilitated patients at the extremesof life. It is also a feature of patients with xerostomiadue to irradiation, Sjögren syndrome and a widevariety of medications, particularly the tricyclic antidepressants.In addition, it is now increasingly becoming afeature of immunosuppressed individuals. Other factorspredisposing to the development of thrush include irondeficiency anaemia, broad spectrum antibiotics and steroidinhalers used for the control of asthma. It is characterisedclinically by the formation of soft, creamy-white,friable plaques that can be easily wiped off to leave underlyingerythematous areas of mucosa. The soft palateand areas protected from friction such as the vestibularreflections are the most common sites.Microscopically, the characteristic plaque of thrushis due to invasion of the superficial epithelial layers bycandidal hyphae and the subsequent proliferative epithelialresponse (Fig 3.8) [26]. The surface epithelium isparakeratinised, oedematous and infiltrated by numerousneutrophils. Candidal hyphae penetrate the epitheliumvertically and extend downwards as far as the glycogen-richlayer. The hyphae may be inconspicuous inH&E sections unless the microscope condenser is loweredto increase their refractility, but they can be readilyvisualised with periodic acid Schiff or Grocott’s silverstains. The epithelium may show hyperplastic but attenuatedrete processes and there is variable but occasionallyflorid acute inflammation of the underlying corium.Denture-induced stomatitis is a variant of atrophiccandidosis. It is typically seen in the hard palate beneatha full or partial dental prosthesis, particularly one constructedfrom acrylic. There is a sharply demarcatedarea of bright red, often boggy erythema limited by theextent of the denture. Occasionally there may be a fewflecks of thrush, but typically there is no plaque formation.Although sometimes referred to as “denture soremouth” the condition rarely causes any symptoms un-