Pathology of the Head and Neck

76 J.W. Eveson3Fig. 3.3. Mucous membrane pemphigoid showing clean subepithelialblisteringFig. 3.4. Dermatitis herpetiformis showing polymorphonuclearleukocytes at the tips of the papillary coriumpemphigoid from several other common oral mucosalinflammatory disorders. For example, lichen planusdoes not have linear immunoglobulin deposits, but haslinear and shaggy deposits of fibrin in the BMZ, and erythemamultiforme has no linear BMZ deposits. However,these deposits do not distinguish mucous membranepemphigoid from bullous pemphigoid, epidermolysisbullosa aquista or linear IgA bullous dermatosis. Suchdistinctions should be made on the basis of clinical findings.Several possible target antigens have been identifiedin the sera of patients with mucous membrane pemphigoid.These include: bullous pemphigoid antigens 1 and2; laminins 5 and 6; type VII collagen and ß4 integrinsubunit [32].3.2.9 Dermatitis HerpetiformisDermatitis herpetiformis is an uncommon, intenselypruritic mucocutaneous disorder related to coeliac diseasethat only occasionally involves the mouth [126].Oral lesions present as areas of erythema and clustersof small, friable vesicles or superficial, painful ulcers.The lesions can involve both keratinised and non-keratinisedmucosa and head and neck cutaneous lesionstend to affect the scalp and periorbital regions. Dermatitisherpetiformis is seen most frequently in teenagersand young adults, particularly males, and there is a predilectionin people of Anglo-Saxon and Scandinavianorigin. There is a strong association between dermatitisherpetiformis and gluten-sensitive enteropathy. TheClass I antigen HLA-B8 is found in the large majorityof patients with both dermatitis herpetiformis and coeliacdisease, and HLA-DR3 is expressed in nearly 95%of patients.Clinically, oral dermatitis herpetiformis presents aspatches of mucosal erythema, clusters of small vesicles,herpetiform ulcers or more extensive areas of non-healingulceration. In conventional gluten-sensitive enteropathyoral ulcers tend to be of the typical minor aphthousstomatitis type.Microscopically, the lesions of dermatitis herpetiformisshow polymorphonuclear leukocyte microabscessesin the tips of the papillary corium (Fig. 3.4). Initially,neutrophils predominate, but as the microabscessesenlarge eosinophils become more conspicuous. The microabscesseseventually fuse to form visible blisters thatfrequently rupture leaving superficial ulcers. Direct immunofluorescenceshows granular deposits of IgA in theBMZ of the dermal papillae, in both affected and adjacentnormal mucosa.3.2.10 Linear IgA diseaseLinear IgA disease is a rather poorly defined heterogeneousgroup of mucocutaneous blistering disordersthat closely resemble mucous membrane pemphigoidclinically and microscopically [160, 191]. Like pemphigoid,the eyes may be involved. Linear IgA diseasein adults has been separated from similar conditionsin childhood such as bullous dermatosis of childhoodand childhood cicatricial pemphigoid. Cutaneous linearIgA disease of adults has a strong association with ahistory of bowel disease. This association is much lessclear in patients with oral lesions. However, patientswith oral linear IgA disease appear to have a higherrisk of severe ocular lesions. Some cases of oral lesionshave been associated with drugs [51]. The conditionis more common in women than men and it usuallypresents as a desquamative gingivitis with, or without,ulceration.Microscopy shows subepithelial vesiculation andfull thickness blister formation. Direct immunofluorescenceshows linear deposition of IgA along the BMZand a low titre of circulating IgA to the BMZ. Althoughsmall amounts of IgG, IgM and C3 may be seen, if these