Gastrointestinal Tract Pathology PDF

Gastrointestinal Tract Pathology Dr. Sara Hassan ORAL CAVITY  Teeth and Supporting Structures Caries (Tooth Decay): Caries represents focal tooth degradation due to mineral dissolution; it occurs through acids released by oral bacteria during sugar fermentation. Caries is the most co...

Gastrointestinal Tract Pathology Dr. Sara Hassan ORAL CAVITY  Teeth and Supporting Structures Caries (Tooth Decay): Caries represents focal tooth degradation due to mineral dissolution; it occurs through acids released by oral bacteria during sugar fermentation. Caries is the most common reason for tooth loss before age 35 years.  Gingivitis: Gingivitis is soft tissue inflammation of the squamous mucosa and soft tissues around teeth, with erythema, edema, bleeding, and gingival degeneration. Inadequate oral hygiene leads to accumulation of dental plaque (a biofilm of bacteria, salivary proteins, and desquamated epithelial cells).  Periodontitis : Periodontitis is inflammation of tooth-supporting structures (e.g., periodontal ligaments, alveolar bone, and cementum)  Inflammatory/Reactive Tumor-Like Lesions Fibrous Proliferative Lesions These are benign reactive lesions, usually cured by surgical excision. -Irritation fibromas : typically occur along the “bite line”; these are nodules of fibrous tissue covered by squamous mucosa. -Pyogenic granulomas : are rapidly growing, highly vascular lesions similar to granulation tissue. Common in children or during pregnancy, they can regress (particularly after pregnancy), can undergo fibrous maturation, or develop into peripheral ossifying fibromas Fibroma. Smooth, pink, exophytic nodule on the buccal mucosa. Pyogenic granuloma. Erythematous, hemorrhagic, and exophytic mass arising from the gingival mucosa. Peripheral ossifying fibromas : can arise from pyogenic granulomas, although most have unknown etiologies. With a 15% to 20% recurrence rate, surgical excision to the periosteum is the treatment of choice. Peripheral giant cell granulomas : are composed of multinucleated foreign body–like giant cells separated by fibroangiomatous stroma.  Apthous Ulcers (Canker Sores) : Lesions are painful, shallow, hyperemic ulcerations initially infiltrated by mononuclear inflammatory cells; secondary bacterial infection recruits neutrophils. Aphthous ulcer. Single ulceration with an erythematous halo surrounding a yellowish fibrinopurulent membrane. Glossitis : Glossitis implies tongue inflammation, but it is also applied to the “beefy-red” tongues of certain deficiency states associated with papilla atrophy and mucosal thinning, exposing the underlying vasculature. Such changes occur in sprue and in vitamin B12, riboflavin, niacin, iron, or pyridoxine deficiencies.  Infections Normal oral mucosa resists infection by competitive suppression from low-virulence commensal organisms, high levels of immunoglobulin A, the antibacterial properties of saliva, and dilution from ingested food and liquids. Alteration in these defenses (e.g., due to immunodeficiency or antibiotic therapy) contributes to infections.  Herpes Simplex Virus Infections : Herpes simplex virus-1 and -2 (HSV-1 and -2) infections classically cause “cold sores” with minimal morbidity; 10% to 20% of primary infections present as acute herpetic gingivostomatitis with diffuse oral vesicles and ulceration, lymphadenopathy, and fever. Morphology: Lesions consist of vesicles, large bullae, or shallow ulcerations. Histologically, there is intra- and intercellular edema , eosinophilic intranuclear inclusions, and multinucleated giant cells (visualized by microscopic examination of vesicular fluid, called a Tzanck test). Vesicles heal spontaneously in 3 to 4 weeks, but virus treks along regional nerves and becomes doermant in local ganglia; reactivation (e.g., driven by trauma, infection, or immune suppression) occurs with crops of small vesicles that clear in 4 to 6 days. Tzanck test Oral Candidiasis (Thrush) : Oral candidiasis can present as erythematous or hyperplastic lesions, but it classically manifests as superficial gray-white inflammatory membranes composed of fibrinosuppurative exudates containing fungus. It occurs with broad-spectrum antibiotics, diabetes, neutropenia, or immunodeficiency. Tumors and Precancerous Lesions Leukoplakia and Erythroplakia : Tobacco use. Leukoplakia : signifies a white plaque on the oral mucosa that cannot be removed by scraping and cannot be classified as another disease entity. Lesions vary from benign epithelial thickenings to highly atypical dysplasia verging on carcinoma in situ. Leukoplakia occurs in 3% of individuals; 5% to 25% of lesions are premalignant. Erythroplakia: is a red, velvety, relatively flat lesion; it is less common than leukoplakia but has greater risk of malignant transformation. Squamous Cell Carcinoma : Tobacco and alcohol are the most common associations, although 50% of oropharyngeal cancers harbor ongogenic variants of human papillomavirus (HPV). Patients with HPV-positive tumors do better than those without. Other risk factors: Familial associations, related to genomic instability Actinic radiation (sunlight) Pipe smoking Betel nut and paan chewing (India and Asia)  Odontogenic Cysts and Tumors Epithelium-lined cysts in the mandible and maxilla derive from odontogenic remnants; they may be developmental or inflammatory. Dentigerous cysts : originate near crowns of unerupted teeth and may result from dental follicle degeneration. They are most often associated with impacted third molars. These are unilocular lesions lined by stratified squamous epithelium, with associated chronic inflammation. Complete removal is curative.  Odontogenic tumors Ameloblastoma: is a true neoplasm arising from odontogenic epithelium. It is typically cystic, slow growing, and locally invasive. Odontoma ; is the most common odontogenic tumor. It is likely a hamartoma, arising from epithelium with extensive enamel and dentin deposition.  SALIVARY GLANDS There are three major salivary glands Parotid Submandibular Sublingual Minor salivary glands All these glands are subject to inflammation or to the development of neoplasms.  Pleomorphic Adenoma These are benign tumors exhibiting mixed epithelial and mesenchymal differentiation; they constitute 60% of all parotid tumors, and lesser percentages in other salivary glands. Tumors are painless, slow-growing, mobile, discrete masses, with epithelial nests dispersed in a variable matrix of myxoid, hyaline, chondroid, or osseous differentiation. Recurrence rates approach 25% if not well excised. Malignant transformation (usually as adenocarcinoma or undifferentiated carcinoma) occurs in 10% of tumors of more than 15 years of duration. Malignant transformation is associated with 30% to 50% 5-year mortality PA PA Oral Manifestations of Systemic Disease