Pathology of the Head and Neck

18 N. Gale · N. Zidar1Fig. 1.15. Verrucous carcinoma. a Projectionsand invaginations lined by thick, welldifferentiatedsquamous epithelium withmarked surface keratinisation, invading thestroma with well-defined pushing margins.b Squamous epithelial cells are large andlack the usual cytologic criteria of malignancy.There are numerous dyskeratotic cellsab1.3.4.2 Pathologic FeaturesMacroscopically, VC usually presents as a large, broadbased exophytic tumour with a white keratotic andwarty surface. On the cut surface, it is firm or hard, tanto white, and may show keratin-filled surface clefts. It isusually large by the time of diagnosis, measuring up to10 cm in its greatest dimension.Microscopically, VCs consist of thickened clubshapedfiliform projections lined with thick, well-differentiatedsquamous epithelium with marked surface keratinisation(“church-spire” keratosis). The squamousepithelial cells in VCs are large [71] and lack the usualcytologic criteria of malignancy. Mitoses are rare, andare only observed in the suprabasal layer; there are noabnormal mitoses. VCs invade the subjacent stromawith well-defined pushing rather than infiltrative borders(Fig. 1.15). A lymphoplasmacytic inflammatory responseis common in the stroma.Hybrid (mixed) tumours also exist composed of VCand conventional well-differentiated SCC; the reportedincidence for the oral cavity and the larynx is 20 and10% [274] respectively. It is important to recognise suchhybrid tumours as foci of conventional SCC in an otherwisetypical VC indicate a potential for metastasis. Orvidaset al. reported that a patient with a hybrid carcinomaof the larynx died of the disease [274]. Patients with hybridcarcinomas must be treated aggressively as if theyhad conventional SCCs [274].Verrucous carcinoma is characterised by a high frequencyof initial misdiagnosis; Orvidas et al. reporteda series of 53 laryngeal VCs; 16 out of 31 patients(52%) had received an incorrect diagnosis of a benignlesion [274]. This emphasises the need for close cooperationbetween the pathologist and the clinician in orderto establish the diagnosis of VC. An adequate, fullthicknessbiopsy specimen must be taken when a cliniciansuspects a VC [274]; moreover, multiple biopsiesmay be needed to rule out a conventional SCC componentin a VC.1.3.4.3 Differential DiagnosisDifferential diagnosis includes verrucous hyperplasia,well-differentiated SCC, papillary SCC, and squamouspapilloma.Invasion below the level of the basal cell layer of theneighbouring normal squamous epithelium distinguishesVC from verrucous hyperplasia. Whether this feature,however, adequately discriminates between VC and verrucoushyperplasia is debatable, as verrucous hyperplasiacould be an exophytic form of VC as well [327].Lack of atypia helps to rule out the conventional SCCand papillary SCC. The VC also lacks the well-formed,wide papillary fronds of a squamous cell papilloma.An additional feature supporting the diagnosis ofa VC is the enlarged spinous cells by morphometricalanalysis [71].1.3.4.4 TreatmentVerrucous carcinoma may be treated by excision (by laseror surgery), and by radiotherapy. It appears that surgeryis a more effective treatment for VC [236, 274]. Hagenet al. reported a 92.4% cure rate for primary surgeryin patients with laryngeal VC [145]. In contrast, Ferlitoand Recher reported a 29% cure rate for radiotherapy inlaryngeal VC [107]. Other studies have shown a 46–57%rate of failure for primary radiation therapy in VCs [224,243, 353].Furthermore, early reports suggested anaplastictransformation following radiotherapy [95, 107, 145,