Page 407 - Concise Pathology for Exam Preparation ( PDFDrive )

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392 SECTION II Diseases of Organ Systems

tumour refers to an otherwise benign pleomorphic adenoma that develops meta-
static deposits of tumour.
• Microscopically, carcinoma expleomorphic adenoma most often is an undifferentiated
carcinoma (30%) or adenocarcinoma (25%). This tumour tends to be more aggressive
than other salivary malignancies.

Polymorphous Low-Grade Adenocarcinoma
• Polymorphous low-grade adenocarcinoma (PLGA) is the second most common malig-
nancy in the minor salivary glands and occurs most frequently in the palate, lip and
buccal mucosa.
• This tumour typically presents in the seventh decade of life and is more common in
women.
• True to its name, any growth pattern (solid, tubular, trabecular, glandular, cribriform
and cystic) can be seen within the same lesion or in different lesions.
• PLGA displays a tendency for perineural and perivascular invasion; however, it typically
follows an indolent course. Treatment is complete local excision.

OESOPHAGUS
Adult oesophagus is 24–30 cm in length from cricoid to oesophagogastric junction and
38–40 cm from dental incisors. For the purpose of classification, staging and reporting of
oesophageal carcinoma, oesophagus is divided into four segments, namely:
(a) Cervical: Cricoid to thoracic inlet
(b) Upper thoracic segment: Thoracic inlet to tracheal bifurcation
(c) Mid-thoracic segment: Tracheal bifurcation to 8th cervical vertebra
(d) Lower thoracic segment: 8th cervical vertebra to the stomach

Histology
• Oesophageal mucosa is lined by nonkeratinized stratified squamous epithelium.
• Lamina propria is composed of connective tissue.
• Muscularis mucosae is thicker than in the other parts of GIT.
• Mucous glands are present in the uppermost and lowermost regions; glands in the
lowermost region resemble cardiac glands of the stomach.
• Submucosa is composed of branched tubular mucous glands throughout.
• Muscularis externa is composed variably of:
• Striated muscle (forms pharyngoesophageal sphincter) in the upper one-third
• Has both smooth and striated muscles in the middle one-third
• Smooth muscle in the lower one-third (forms lower oesophageal sphincter (LES)
lower one-third)
• Muscularis externa has two layers—outer longitudinal and inner circular
• Adventitia has connective tissue blending with the surrounding tissue.

Q. Write briefly on achalasia cardia.
Ans. Achalasia cardia is caused by a failure of relaxation of LES and has the following features:
• Complete absence of peristalsis and elevation of resting LES pressure or low amplitude
nonperistaltic contractions
• Increased intraoesophageal pressure
• Functional obstruction of oesophagus with a dilated fluid and food-filled proximal
portion
Age

20–40 years
Symptoms
Progressive dysphagia for solids and liquids, regurgitation, chest pain and weight loss

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