Pathology of the Head and Neck

288 M.R. Canninga-Van Dijk10the causative agent in cell cultures and the detection ofchlamydial antibody in blood or tear fluid. At Stage Ithere is epithelial infection by Chlamydia trachomatis.It is characterised clinically by the formation of conjunctivalfollicles and diffuse punctate inflammationof the cornea. The histology is indistinguishable fromthat of follicular conjunctivitis caused by other agents.Lymphocytes and plasma cells infiltrate the subepithelialtissue; polymorphonuclear leukocytes infiltrate thecorneal and conjunctival epithelium. At Stage II, theinflammatory reaction occupies the stroma, with thefurther formation of follicles. Large macrophages withphagocytised debris (Leber cells) are seen in the conjunctiva,accompanying the epithelial hyperplasia withround cell infiltration and subepithelial oedema [125].At Stage III the follicles disappear and cicatrisationoccurs. The fibrosis causes inversion of the upper lid(cicatricial entropion), misdirected lashes (trichiasis)and decreased tear formation. On histologic examination,scattered lymphocytes and plasma cells can stillbe seen along with subepithelial scar tissue. At StageIV, there is spontaneous arrest of the disease, which isno longer contagious. The residual entropion and trichiasislead to continuing corneal damage. Denudingof the epithelium leaves the cornea vulnerable to infectionand further opacification as a result of scarring.10.2.4.5.2 Inclusion ConjunctivitisThe conjunctival involvement of the sexually transmittedchlamydial infection is mild and can even be asymptomatic.In adults, it presents as a subacute follicularconjunctivitis. It is accompanied by a chronic urethritisin the male and a symptomless cervicitis in the female.In newborns, it occurs with an acute mucopurulentdischarge, 5 to 10 days after birth. It is accompaniedby infection of the maternal vagina by the same agent.Because the extranodal lymphoid tissues are not fullydeveloped, the conjunctivitis is more papillary than follicular.Like trachoma it can be diagnosed by Giemsastaining on conjunctival scrapings.10.2.5 Dermatologicand Systemic Diseases10.2.5.1 Keratoconjunctivitis SiccaIn this condition the cornea and conjunctiva are dry,causing a painful and gritty sensation. Keratoconjunctivitissicca was described first by Sjögren in 1933 [106,107]. It is therefore best known as one of the symptomsof Sjögren’s syndrome. However, it can also be seen inother auto-immune diseases like scleroderma or rheumatoidarthritis. Moreover, keratoconjunctivitis sicca isthe most frequent cause of eye involvement in graft-versus-hostdisease [20, 50, 64]. Histologically, there is atrophyof the lacrimal acinar parenchyma, accompanied byfibrosis and fatty infiltration, but with preservation ofthe lobular architecture. There is a focal or diffuse presenceof lymphocytes and plasma cells. Sometimes lymphoepitheliallesions can be seen (See Chap. 5 for moredetail.).10.2.5.2 Dermatologic DiseasesMany skin diseases can involve the conjunctiva. Mostfrequently seen are bullous diseases like pemphigus [72],bullous pemphigoid, Stevens-Johnson syndrome [43],paraneoplastic pemphigus [58, 74] and less commonly,dermatitis herpetiformis [43] and linear IgA disease [4].Other dermatologic diseases with conjunctival involvementare lupus erythematosus [40, 115, 122], familialchronic benign pemphigus (Hailey-Hailey disease) [80]and lichen planus [78, 116].10.2.5.3 Metabolic DiseasesA conjunctival biopsy can be of diagnostic value in metabolicdiseases with specific ultrastructural features,like galactosialidosis and different types of mucopolysaccharidoses[14, 121].10.2.6 Tumoursand Tumour-Like Conditions10.2.6.1 EpithelialEpithelial tumours of the conjunctiva can be dividedinto tumours of the surface epithelium (papilloma, intraepithelialneoplasia and squamous cell carcinoma)and adnexal tumours. Since the caruncle contains accessorylacrimal glands, sweat glands, hair follicles andsebaceous glands, adnexal tumours of different kindscan be found.10.2.6.1.1 PapillomaICD-O:8560/0The commonest epithelial tumours of the conjunctivaare papillomas, usually presenting as a red, papillomatousmass. These benign tumours histologicallyconsist of a fibrovascular core, lined with conjunctivalepithelium, eventually with squamous metaplasia(Figs. 10.6, 10.7). The sessile variant usually shows only