Oral Cavity Pathology PDF

Pathology of the oral cavity Dr. Azza Zulfu & Dr. Alshima Adam Overview of oral cavity pathology : a/Diseases of Teeth and Supporting Structures: - Caries -Gingivitis -Periodontitis b/Oral Inflammatory Lesions: - Aphthous Ulcers (Canker Sores) - Herpes Simplex Virus Infect...

Pathology of the oral cavity Dr. Azza Zulfu & Dr. Alshima Adam Overview of oral cavity pathology : a/Diseases of Teeth and Supporting Structures: - Caries -Gingivitis -Periodontitis b/Oral Inflammatory Lesions: - Aphthous Ulcers (Canker Sores) - Herpes Simplex Virus Infections 584 - Oral Candidiasis (Thrush) c/Proliferative and Neoplastic Lesions of the Oral Cavity: -Fibrous Proliferative Lesions -Leukoplakia and Erythroplakia -Squamous Cell Carcinoma DISEASES OF TEETH AND SUPPORTING STRUCTURES Caries : Definition :Dental caries results from focal demineralization of tooth structure (enamel and dentin) caused by acids generated during the fermentation of sugars by bacteria. -The prevalence of caries are high with consuming foods containing large amounts of carbohydrates. - the rate of caries drops markedly with improved oral hygiene , improved and fluoridation of the drinking water - Question : How can floridation of water prevent Caries ??? Answer : Fluoride is incorporated into the crystalline structure of enamel, forming fluoroapatite, which is resistant to degradation by bacterial acids. Gingivitis : Defintion : Is the Inflammation involving the squamous mucosa, or gingiva, and associated soft tissues that surround teeth. - Poor oral hygiene, which facilitates buildup of dental plaque and calculus between and on the surfaces of teeth, is the most frequent cause of gingivitis. -Dental plaque is a sticky biofilm composed of bacteria, salivary proteins, and desquamated epithelial cells. -As it accumulates, plaque becomes mineralized to form calculus, or tartar. In chronic gingivitis, this is accompanied by gingival erythema, edema, and bleeding. Periodontitis Periodontitis is an inflammatory process that affects : 1/the supporting structures of the teeth (periodontal ligaments), 2/alveolar bone, 3/ and cementum. - Facultative Gram-positive organisms are found at healthy sites, while anaerobic and microaerophilic Gram-negative bacteria colonize plaque within areas of active periodontitis. - A bout 300 bacterial species reside within the oral cavity,BUT periodontitis is most closely associated with Aggregatibacter (Actinobacillus) actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia SUMMARY DISEASES OF TEETH AND SUPPORTING STRUCTURES: 1/ Caries is the most common cause of tooth loss in individuals younger than 35 years of age. The primary cause is destruction of tooth structure by acid end products of sugar fermentation by bacteria.  2/ Gingivitis is a common and reversible inflammation of the mucosa surrounding the teeth. It is associated with buildup of dental plaque and calculus 3/ Periodontitis is a chronic inflammatory condition that can lead to the destruction of the supporting structures of the teeth with eventual loss of dentition. It is associated with poor oral hygiene and altered oral microbiota. ORAL INFLAMMATORY LESIONS : 1/Aphthous Ulcers (Canker Sores): - Are common superficial mucosal ulcerations affect up to 40% of the population. - Are more frequent in the first 2 decades of life, - Are extremely painful, and often recur. - Despite being of unknown cause ; they tend to be familal and may be associated with celiac disease, inflammatory bowel disease, and Behçet disease. - Can be solitary or multiple. - Typically, they are shallow, with a hyperemic base covered by a thin exudate and rimmed by a narrow zone of erythema (Fig ). - In most cases they resolve spontaneously in 7 to 10 days but can recur.  Aphthous ulcer. :Single ulceration with an erythematous halo surrounding a yellowish fibrinopurulent membrane.  2/ Herpes Simplex Virus Infections: - Herpes simplex virus causes a self-limited primary infection that can be reactivated when there is a compromise in host resistance. - Most orofacial herpetic infections are caused by herpes simplex virus type 1 (HSV-1), less commonly caused by HSV-2 (genital herpes). -Primary infections typically occur in children and are often asymptomatic. - In 10% to 20% of cases, the primary infection manifests as acute herpetic gingivostomatitis, with abrupt onset of vesicles and ulcerations throughout the oral cavity. - Most adults harbor latent HSV-1, and the virus can be reactivated. - Factors associated with HSV reactivation include: - trauma, - allergies, - exposure to ultraviolet light - extremes of temperature, - upper-respiratory tract infections, -pregnancy, -menstruation, - immunosuppression. Recurrent lesions , typically appear as groups of small (1- to 3-mm) vesicles.  -The most common locations for herpes lesions are : The lips (herpes labialis), nasal orifices, buccal mucosa, gingiva, hard palate - Although lesions typically resolve within 7 to 10 days, they can persist in immunocompromised patients, who may require systemic anti-viral therapy. -Morphologically ;The infected cells become ballooned and have large eosinophilic intranuclear inclusions. Adjacent cells commonly fuse to form large multinucleated polykaryons. 3/Oral Candidiasis (Thrush): -Candidiasis is the most common fungal infection of theoral cavity. Candida albicans is a normal component of the oral flora and only produces disease under unusual circumstances. -Predisposing factors include the following: Immunosuppression The specific strain of C. albicans The composition of the oral microbial flora (microbiota) NB: Broad-spectrum antibiotics that alter the normal microbiota can promote oral candidiasis. -The three major clinical forms of oral candidiasis are : pseudomembranous, erythematous, hyperplastic.  -The pseudomembranous form is most common and is known as thrush. -In mildly immunosuppressed cases such as diabetics, the infection usually remains superficial, - In more severe immunosuppression the infection may spread to deep sites ( e.g organ or hematopoietic stem cell transplant recipients, and in patients with neutropenia, chemotherapy-induced immunosuppression, or AIDS).  SUMMARY ORAL INFLAMMATORY LESIONS - Aphthous ulcers are painful superficial ulcers of unknown etiology that may in some cases be associated with systemic diseases. - Herpes simplex virus causes a self-limited infection that presents with vesicles (cold sores, fever blisters) that rupture and heal, without scarring, and often leave latent virus in nerve ganglia. Reactivation can occur. - Oral candidiasis may occur when the oral microbiota is altered (e.g., after antibiotic use). Invasive disease may occur in immunosuppressed individuals. PROLIFERATIVE AND NEOPLASTIC LESIONS OF THE ORAL CAVITY Fibrous Proliferative Lesions: -Fibromas are submucosal nodular fibrous tissue masses that are formed when chronic irritation results in reactive connective tissue hyperplasia - They occur most often on the buccal mucosa along the bite line. Treatment is complete surgical excision and removal of the source of irritation. Pyogenic granuloma is an inflammatory lesion typically found on the gingiva of children, young adults, and pregnant women. -These lesions are richy vascular and typically ulcerated, which gives them ared to purple color. -In some cases, growth can be rapid and raise fear of a malignant neoplasm. - Histologic examination demonstrates a proliferation of immature vessels similar to that seen in granulation tissue. -Complete surgical excision is definitive treatment. Fig. Fibrous proliferations. (A) Fibroma. Smooth pink exophytic nodule on the buccal mucosa. (B) Pyogenic granuloma. Erythematous hemorrhagic exophytic mass arising from the gingival mucosa. Leukoplakia and Erythroplakia Leukoplakia is defined by the World Health Organization as “a white patch or plaque that cannot be scraped off and cannot be characterized clinically or pathologically as any other disease.” - Approximately 3% of the world’s population has leukoplakic lesions, of which 5% to 25% are dsyplastic and at risk for progression to squamous cell carcinoma. - Thus, until proved otherwise by means of histologic evaluation, all leukoplakias must be considered precancerous  - A related but less common entity, erythroplakia, is a red, velvety, sometimes eroded lesion that is flat or slightly depressed relative to the surrounding mucosa. -Erythroplakia is associated with a much greater risk for malignant transformation than leukoplakia. - Although the etiology is multifactorial,tobacco use (cigarettes, pipes, cigars, and chewing tobacco) is the most common risk factor for leukoplakia and erythroplakia.  MORPHOLOGY : On histologic examination leukoplakia and erythroplakia show a spectrum of epithelial changes ranging from hyperkeratosis to lesions with markedly dysplastic changes to carcinoma in situ Leukoplakia. (A): Gross appearance of leukoplakia is highly variable.In this example, the lesion is smooth with well demarcated borders and minimal elevation. (B) Histologic appearance of leukoplakia showing dysplasia, characterized by nuclear and cellular pleomorphism and loss of normal maturation. Squamous Cell Carcinoma : - Approximately 95% of cancers of the oral cavity are squamous cell carcinomas - Squamous cell carcinoma, is the sixth most common neoplasm in the world. - Despite numerous advances in treatment, the overall long-term survival rate is low - The poor outcome is mainly due to diagnosis at an advanced stage. Pathogenesis : -Squamous cancers of the oropharynx arise through two distinct pathogenic pathways: 1/ pathway involving exposure to carcinogens 2/ pathway related to infection with high risk variants of human papilloma virus (HPV).. Characteristics of carcinogen exposure - related tumors : a/ Stem from chronic alcohol and tobacco (both smoked and chewed) use. b/ Deep sequencing of these cancers has revealed frequent mutations that frequently involve: TP53 and genes that regulate cell proliferation, such as RAS Characteristics of HPV-related tumors : a/ tend to occur in the tonsillar crypts or the base of the tongue b/ harbor oncogenic “high-risk”subtypes, particularly HPV-16. c/ carry far fewer mutations than those associated with tobacco exposure and d/ Often overexpress p16, a cyclin-dependent kinase inhibitor. MORPHOLOGY(1) -Squamous cell carcinoma may arise anywhere in the oral cavity. -However, the most common locations are the ventral surface of the tongue, floor of the mouth, lower lip, soft palate, and gingiva. - In early stages, these cancers may appear as raised, firm, pearly plaques or as irregular, roughened, or verrucous mucosal thickenings. -Either pattern may be superimposed on a background of leukoplakia or erythroplakia.  MORPHOLOGY(2) - Histopathologic analysis has shown that squamous cell carcinoma develops from dysplastic precursor lesions. - Histologic patterns range from well differentiated keratinizing neoplasms to anaplastic tumors -Typically, oral squamous cell carcinoma infiltrates locally before it metastasizes. -The cervical lymph nodes are the most common sites of regional metastasis - frequent sites of distant metastases include the mediastinal lymph nodes, lungs, and liver  B A Oral squamous cell carcinoma: (A) Gross appearance demonstrating ulceration and induration of the oral mucosa. (B) Histologic appearance demonstrating numerous nests and islands of malignant keratinocytes invading the underlying connective tissue stroma. SUMMARY: LESIONS OF THE ORAL CAVITY - Fibromas and pyogenic granulomas are common reactive lesions of the oral mucosa. - Leukoplakia and eryhtroplakia are mucosal plaques that may undergo malignant transformation. - The risk for malignant transformation is greater in erythroplakia (relative to leukoplakia). - A majority of oral cavity cancers are squamous cell carcinomas. - Oral squamous cell carcinomas are classically linked to tobacco and alcohol use, but the incidence of HPV-associated lesions is rising.