Immune Mediated Disorders - RAS

Immune Mediated Disorders - Recurrent Aphthous Stomatitis (RAS)

• Recurrent aphthous stomatitis (RAS) is a common condition affecting the oral mucosa.
• Three types exist: minor, major, and herpetiform.
• Aphthous minor RAS is the most common type.
• Painful, small, superficial ulcers of the oral mucosa, occurring in clusters of 1-5 lesions.
• Peak age of onset is 10-19 years.
• Lesions typically occur on the lips, posterior soft palate, and anterior fauces.
• Individual ulcers are round or elliptical (if located in a crease or fold), 0.5mm to 1.0cm in diameter.
• Ulcers have sharp crateriform edges and a whitish-yellow base with erythematous halo.
• Healing takes 10-14 days, with new lesions possible for 3-4 weeks.
• Histopathology shows a mild infiltrate of T4 helper and lymphocytes in perivascular locations of the submucosal tissue.
• Ulcerative stage shows epithelial changes with vacuolization and necrosis.

Immune Mediated Disorders - Aphthous Major RAS

• Less common than minor RAS.
• Large, superficial, painful ulcers (5mm-20mm or more)
• Typically on labial mucosa and soft palate.
• Healing time is up to 6 weeks, and pain more intense, especially with food.
• Healing often leaves a scar.
• The lesion may occur over areas with many minor salivary glands.
• Histopathology shows fibrinopurulent exudate, more extensive connective tissue involvement, and prominent lymphocytes in perivascular regions.

Immune Mediated Disorders - Aphthous Herpetiform RAS

• Identical to aphthous minor but with multiple small ulcers.
• No scarring.
• Cytology smears show no cytopathic effects, unlike viral infections.
• Important to rule out primary herpetic stomatitis.

Immune Mediated Disorders - Behçet's Syndrome

• A complex multisystem condition, featuring oral, genital, and ocular aphthous-like lesions.
• Symptoms include arthralgia (especially ankles and knees), thrombophlebitis, CNS involvement, and skin lesions (macular and pustular).
• Diagnosed via clinical criteria.
• Linked to HLA-B5 in some regions.
• Oral mucosal lesions are identical to aphthous minor lesions.

Immune Mediated Disorders - Lichen Planus (LP)

• A skin disease that may affect the oral cavity
• May present as reticular, plaque or erosive lesions with a prominent T-lymphocyte response in the immediate underlying connective tissue
• Present on oral and cutaneous surfaces.
• Commonly present as bilateral, thin, white lines that connect in arcuate (bow) patterns
• This pattern can be seen in places like buccal mucosa, buccal vestibule, but not usually as a primary feature of the hard or soft palate
• Causes are currently unknown, but some correlation to Hepatitis C has been suggested.
• Histological features include epithelial hyperplasia with thickened spinous cell layers.

Immune Mediated Disorders - Lichenoid Reactions

• Similar to lichen planus but not primary LP
• Usually caused by medications, or other factors.
• Oral and skin lesions
• Histology is similar to LP

Immune Mediated Disorders - Mucous Membrane Pemphigoid

• A desquamating autoimmune condition affecting mucous membranes, commonly gingiva.
• Characterized by epithelial separation at the basement membrane level.
• Often presents with blistering or erosions, especially on attached gingiva and palatal mucosa.
• A Nikolsky sign is diagnostic.
• Associated with oral lesions that may be described as atrophic erythematous patches, erosions, pseudomembranes or collapsed blisters.

Immune Mediated Disorders - Pemphigus Vulgaris

• A desquamating autoimmune condition mostly appearing on the skin.
• Epithelial separation occurs above the basal cell layer due to autoantibodies targeting desmosomes (desmoglein 1 and 3).
• Oral lesions are common and described as erosive lesions.
• May progress to severe, potentially fatal, widespread skin involvement.

Immune Mediated Disorders - Epidermolysis Bullosa

• A group of genetic diseases with blister formation and widespread skin and mucous membrane involvement.
• These disorders are often genetic.
• Three major types (EBS, JEB, and DEB), categorized by location of cleavage due to defects in different proteins of the basement membrane.
• Oral lesions may be severe, including loss of taste, pain, and difficulty with mastication

Immune Mediated Disorders - Erythema Multiforme

• A hypersensitivity reaction usually in response to an external agent.
• Clinically may be mild (minor) or severe (major).
• Mild may cause skin lesions smaller in size and duration (versus large "target" lesions in more severe cases).
• Often preceded by prodrome (fever, headache).
• Varying oral presentations (aphthous-like to diffuse ulcers)

Immune Mediated Disorders - Lupus Erythematosus

• A chronic inflammatory connective tissue disease.
• Presents as a "butterfly" rash on the face, and other skin lesions, while mucosal lesions are less common but can still be seen in the oral region.
• Typically affects females.
• Symptoms can greatly vary, with involvement in multiple locations including skin and systemic organs.
• Autoimmune reaction involving the mucosa's connective tissue may cause oral ulcers.

Immune Mediated Disorders - Orofacial Granulomatosis

• A condition that presents with non-caseating granulomas.
• Can have a wide variety of presenting symptoms and sites (though can be primarily affect the head and neck).
• Frequently associated with Crohn's disease.
• May affect the mucosal surfaces of the oral cavity.

This quiz focuses on Recurrent Aphthous Stomatitis, a common immune-mediated condition characterized by painful oral ulcers. Learn about the types, symptoms, and histopathological features of RAS, particularly in young individuals. Test your knowledge on its clinical presentation and healing process.