Pathology of the Head and Neck

Lesions of Squamous Epithelium Chapter 1 3munodeficiency syndrome (AIDS) may show a certainamount of epithelial atypia. In these cases SCPs have tobe differentiated from squamous cell carcinoma [295].The treatment for SCPs and related papillary lesionsis surgical removal. The infectivity of HPV in SCPs isvery low and recurrence uncommon, except in lesionsassociated with human immunodeficiency virus (HIV)infections. On the other hand, recurrence is more commonin CAs. No special treatment is required for FEHunless the lesions are extensive.1.1.2 Laryngeal PapillomatosisFig. 1.3. Laryngeal papillomatosis. Numerous clusters of papillomasobliterate the laryngeal lumenICD-O:8060/0Laryngeal squamous cell papillomas (LSCPs) are themost frustrating benign lesions in the head and neckregion. Because of their clinical specificities, such asmultiplicity, recurrence and the propensity to spread toadjacent areas, it has been suggested that LSCPs shouldbe renamed recurrent respiratory papillomatosis (RRP)[34, 89, 91, 187].Recurrent respiratory papillomatosis is aetiologicallyrelated to HPV [4, 212, 283, 289, 352]. HPV-6 and -11 are the most frequent genotypes associated with RRP(Fig. 1.4b) [4, 126, 212, 284, 289, 330].Characteristically, LSCPs show a bimodal age distribution:the first peak is before the age of 5 years with nogender predominance; the second peak occurs betweenthe ages of 20 and 40 years with a male to female ratio of3:2 [34, 87, 91, 189, 216].Human papillomavirus transmission in children isassociated with perinatal transmission from an infectedmother to the child [34, 88, 217]. The mode of HPVinfection in adults remains unclear. The reactivationof a latent infection acquired perinatally or a postpartuminfection with orogenital contacts has been suggested[4, 188]. In contrast to RRP, a solitary keratinisingsquamous papilloma or papillary keratosis of adults appearsnot to be associated with viral infection, althoughit may recur or be occasionally associated with malignanttransformation [20].Recurrent respiratory papillomatosis almost invariablyinvolves the larynx, especially the true and false vocalcords, subglottic areas and ventricles [4]. An extralaryngealspread may occur successively to the oral cavity,trachea and bronchi. Although RRP has been traditionallydivided into juvenile and adult groups [87, 189,216, 352], the prevailing opinion has recognised the diseaseas a unified biological entity with differences inclinical courses, caused by HPV genotypes 6 or 11 [28,126, 189, 218, 321]. For children, multiple and extensivegrowth with rapid recurrence after excision is characteristic.The small diameter of the airways in childrenmay cause dangerous or even fatal airway obstruction.The clinical course in adults is usually not so dramatic,although RRP can be aggressive with multiple recurrences[43, 284]. Most children present with dysphoniaand stridor, and less commonly with a chronic cough,recurrent pneumonia, dyspnoea, and acute life-threateningevents [34, 43, 88]. Affected adults present mostlywith dysphonia and hoarseness [43, 181].Grossly, papillomas are exophytic, branching, pedunculateor sessile masses, pink or reddish in colour, witha finely lobulated surface, presenting either singly or inclusters (Fig. 1.3).Histologically, RRP is composed of finger-like projectionsof the squamous epithelium, covering thin fibrovascularcores. A basal and parabasal hyperplasia ofthe squamous epithelium is most frequently seen, usuallyextending up to the mid-portion (Fig. 1.4a). Mitoticfeatures may be prominent within this area. Irregularlyscattered clusters of koilocytes are seen in the upperpart of the epithelium. Epithelial changes, such as mildto moderate nuclear atypia and hyperchromatism, increasednuclear cytoplasmic ratio, increased mitotic activitywith pathological features, and prominent surfacekeratinisation are rarely found in RRP [181].Various lesions with a papillary structure must beconsidered in the differential diagnosis of RRP. In verrucouscarcinomas, the squamous fronds are thicker andare covered by a prominent keratotic layer, bulbous retepegs infiltrate fibrous stroma in a blunt, pushing mannerand koilocytosis is usually absent. The papillary squamouscarcinoma usually shows an architectonic similarityto RRP. In contrast to RRP, papillary structures in thepapillary squamous carcinoma are covered by a clearlyneoplastic epithelium showing invasive growth.The clinical course of RRP is unpredictable, characterisedby periods of active disease and remissions. HPVpresent in apparently normal mucosa serves as a virusreservoir responsible for repeated recurrence of papillo-