Page 399 - Concise Pathology for Exam Preparation ( PDFDrive )

14

The Oral Cavity and

Gastrointestinal Tract

ORAL CAVITY
• The process of digestion starts in the oral cavity, which is the beginning of the gastroin-
testinal tract (GIT). It has many supporting structures, like the lips, teeth and tongue.
Oral cavity has two main parts: the outer portion or, the vestibule, and an inner mouth
cavity. The vestibule (space between the cheeks and the lips) is smaller than the oral
cavity proper. The stratified squamous nonkeratinized epithelium lining the oral
mucosa changes to stratified squamous keratinized epithelium in the lips.
• The boundaries of the oral cavity include the alveolar arches and teeth (lateral and
front), the pharynx (behind) and the palate (superiorly). The palate consists of two
regions: the anterior two-third or bony part, called the hard palate and the posterior
one-third or fibromuscular part, known as the soft palate. The palate is also lined by
stratified squamous nonkeratinized epithelium.
• The bones that are part of the oral cavity are the maxilla, mandible and the hard palate.
The hard palate is formed by the palatine process of the maxilla and the maxillary
process of the palatine bones.

Q. Write briefly on tumours and tumour-like lesions of oral cavity.
Ans. Benign Tumours and Tumour-Like Lesions
• Common ‘tumour-like lesions’ of the oral cavity include pyogenic granulomas,
fibroepithelial polyps, fibrous epulis, denture hyperplasia and mucoceles.
• Benign tumours in the oral cavity may arise from the following:
1. Squamous epithelium
2. Mesenchymal tissue
3. Minor salivary glands
• The most common benign epithelial neoplasm is squamous papilloma. It is a small,
cauliflower-like, sessile or pedunculated lesion having a central fibrovascular core
covered by hyperplastic (acanthotic), stratified squamous epithelium. Most of these are
viral in origin and show ‘koilocytosis’. Koilocytes are defined as cells showing a hyper-
chromatic nucleus with irregular nuclear membrane surrounded by a clear zone. Other
common epithelium-derived neoplasms in this location are tumours of the minor
salivary glands.
• Benign mesenchymal tumours include haemangioma, lymphangioma, fibroma,
lipoma, neural tumours, etc.
• Granular cell tumour (earlier called granular cell myoblastoma) is a mesenchymal
tumour of the skin and mucosal surfaces. In the oral cavity, it is most commonly located
in the dorsum of the tongue. The tumour comprises large polygonal cells, which have
abundant granular cytoplasm containing cytoplasmic inclusions. The epithelium
overlying the tumour may show pseudoepitheliomatous hyperplasia.

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