Pathology of the Head and Neck

78 J.W. Eveson3(~5%) and are characterised by the formation of sometimeshundreds of small (~2 mm), superficial ulcers thatfrequently coalesce and may form on a background ofmore generalised mucosal erythema [154]. Any oral sitemay be involved, but the labial and ventral lingual mucosaeare the sites of predilection.Although most cases of recurrent aphthous stomatitisare idiopathic, a minority are caused, or exacerbated,by deficiencies in iron, vitamin B 12 or folate, and assuch are potentially curable. Haematinic deficienciesare reported to be twice as common in patients withrecurrent aphthous stomatitis compared with controls.The condition is often made worse by emotional stress.Occasional cases are said to be related to gastro-intestinalcomplaints such as coeliac disease, Crohn’s diseaseand ulcerative colitis, but some of the data are conflicting[56, 164]. However, it is likely that in most instancesany associations are secondary to haematinic deficiencies.It is uncommon for recurrent aphthae to be biopsied,except when a major aphtha simulates malignancy [97].Reported early changes include infiltration of the epitheliumby lymphocytes and histiocytes and focal aggregatesof lymphocytes in the superficial corium. Thisis followed by areas of epithelial cell apoptosis, degenerationand necrosis [77]. The epithelium is lost and thesubsequent ulcer is covered by a fibrinous slough, heavilyinfiltrated by polymorphonuclear leukocytes. Moredeeply there is a mononuclear cell infiltration and perivascularcuffing is an inconsistent feature. The conditionappears to be a T-cell mediated immunological response[62] and is thought to be a response to a keratinocyte-associatedantigen that is yet to be identified.3.3.2 Behçet DiseaseThis condition comprises recurrent oral ulceration togetherwith genital ulceration and ocular lesions [56,88, 109]. The ocular lesions include uveitis and retinalvasculitis. Behçet disease, however, is a multisystemdisorder and can show a wide range of clinical manifestations.Features of more generalised disease includeneurological disorders, arthralgia, and vascular, gastrointestinaland renal lesions. The disease is uncommonthe USA and UK, but has a much higher prevalence insoutheast Asia, Japan and the eastern Mediterranean region.There is a strong association with the presence ofHLA*B51 [116].The oral lesions are clinically identical to recurrentaphthae [177]. Patients also have genital or perigenitalcutaneous ulcers and erythema nodosum is common.Microscopically, like recurrent aphthae, the ulcers associatedwith Behçet disease show essentially non-specificfeatures. It has been suggested that perivascular inflammatoryinfiltration into the deeper corium may bemore characteristic of Behçet disease, but the significanceof this observation is questionable.3.3.3 Reiter DiseaseReiter disease comprises non-specific urethritis, arthritisand conjunctivitis, although the conjunctivitis ispresent in less than half of cases. It was initially thoughtto be only sexually transmitted, but many cases appearto result from enteric infections by a variety of organismsincluding Shigella, Salmonella and Campylobactor.The disease is typically seen in young males andshows a strong association with HLA-B27 and has beenreported in HIV-infected individuals [182]. Patients developpainful mono- or polyarticular arthropathy andoccasionally the temporomandibular joint is involved.Patients can have fever, weight loss and CNS involvement,and facial nerve palsy has been described. Cutaneousand mucosal lesions are relatively common. Theskin lesions include macules, vesicles, and pustules onthe hands and feet particularly, and plaque-like hyperkeratoticlesions of the trunk and scalp. Oral lesionsconsist of circinate white or yellowish lesions surroundingmacular areas that are erythematous or superficiallyulcerated. They resemble circinate balanitis and the lesionsof geographical tongue and geographical stomatitis[131]. They are painless and transient and are thereforerarely biopsied. Microscopy shows features similarto those seen in geographical tongue with spongiformpustules focally and diffusely dispersed in the superficialepithelium, but without evidence of psoriasiformhyperplasia.3.3.4 Median Rhomboid GlossitisMedian rhomboid glossitis usually presents as a painless,reddened, sharply demarcated area of depapillationin the centre of the dorsum of the tongue anterior tothe foramen caecum. In some cases the area is nodularor grooved. It was originally thought to be due to thepersistence of the developmental eminence called thetuberculum impar, but now most cases are believed tobe candidal in origin [180, 188]. Predisposing factorsinclude smoking, wearing dentures, diabetes and usingsteroid inhalers. Sometimes there is a “kissing lesion” inthe palate.Microscopy typically shows elongation, branchingand fusion of the rete ridges with mild epithelial atypia(Fig. 3.5). There may be spongiform pustules in theparakeratinised surface layers and evidence of candidalhyphae. Sometimes the epithelial hyperplasia is floridresulting in a pseudoepitheliomatous appearance. Someof these lesions have been misinterpreted as squamous