Derm_HEENT Notes.docx

THE SKIN NORMAL STRUCTURE and FUNCTION: LAYERS OF EPIDERMIS: Stratus Basale: Contains Stem Cells. Some minimal cell division occurs in this layer. Stratum Spinosum: This is the main proliferative layer. Some synthesis begins in this level too. Membrane-Coating Granules (MCG) begin formation in...

THE SKIN NORMAL STRUCTURE and FUNCTION: LAYERS OF EPIDERMIS: Stratus Basale: Contains Stem Cells. Some minimal cell division occurs in this layer. Stratum Spinosum: This is the main proliferative layer. Some synthesis begins in this level too. Membrane-Coating Granules (MCG) begin formation in this layer, near the top. Stratum Granulosum: This is the mature synthetic layer, where keratinocytes are synthesizing the granular components (Keratin, MCG) of skin. (Stratum Lucidum): Only thick skin, a thin layer of flat cells marking the uppermost border of the Stratum Granulosum. They aren't apparent in thin skin. Stratum Corneum: 15-20 layers of dehydrated, non-nucleated keratinocytes, packed with tonofilaments containing filaggrin. EPIDERMAL MIGRANT CELLS: MELANOCYTES: LANGERHANS CELLS: MERKEL CELLS: DERMAL-EPIDERMAL BASEMENT MEMBRANE ZONE: LAMINA LUCIDA LAMINA DENSA THE DERMIS HAIR FOLLICLES DERMATOLOGY VOCABULARY: Types of Lesions: Macule: A small, discolored patch or spot on the skin, neither elevated above nor depressed below the skin's surface. Papule: A small, circumscribed, solid elevation on the skin, less than 0.5 cm. Plaque: Slightly larger circumscribed elevation, greater than 0.5 cm. Vesicle: A small (less than 0.5 cm) circumscribed elevation of the skin containing fluid. Bulla: A large blister appearing as a circumscribed area of separation of the epidermis from the subepidermal structure (subepidermal bulla) or as a circumscribed area of separation of epidermal cells (intraepidermal bulla) caused by the presence of serum, or occasionally by an injected substance. Pustule: A small circumscribed elevation of the skin, containing purulent material. Eczema: Generic term for inflammatory conditions of the skin, particularly with vesiculation in the acute stage, typically erythematous, edematous, papular, and crusting. Sometimes referred to colloquially as tetter, dry tetter, scaly tetter. Followed often by lichenification and scaling and occasionally by duskiness of the erythema and, infrequently, hyperpigmentation Often accompanied by sensations of itching and burning The vesicles form by intraepidermal spongiosis. Nevus: It literally means a hamartoma. In common use, a benign melanocytic neoplasm of the skin, or mole. Dermatological Structures: Keratinocyte: A keratin-secreting stratified squamous epithelial cell. Panniculus: The superficial fascia which contains an abundance of fat deposit in its areolar substance. Rete Ridges: Downward thickening of the epidermis between the dermal papillae; peg is a misnomer because the dermal papillae are cylindrical but the epidermal thickening between papillae is not. Dermatopathology: Acanthosis: An increase in the thickness of the stratum spinosum of the epidermis. Acantholysis: Separation of individual epidermal keratinocytes from their neighbor, as in conditions such as Pemphigus Vulgaris and Darier's disease. Parakeratosis: Retention of nuclei in the cells of the stratum corneum of the epidermis, observed in many scaling dermatoses such as psoriasis and subacute or chronic dermatitis. Hyperkeratosis: Thickening of the horny layer of the epidermis or mucous membrane. SELECTED INFECTIONS with CUTANEOUS MANIFESTATIONS: BACTERIAL INFECTIONS: IMPETIGO: Staphylococcus Aureus. Weeping, oozing lesions; red patches developing into pustules. SCALDED-SKIN SYNDROME: Staphylococcus Aureus. Bullous lesions leading to desquamation in infants. It is a result of the toxin -- not the bugs themselves. No bugs are found in the lesion. It will heal without scarring, if treated carefully and not spread. TINEA (RINGWORM): Fungal infection caused by the dermatophytes, Epidermophyton, Microsporum, and Trichophyton. PATHOLOGY: The fungi infect the stratum corneum layer of the epidermis. They don't go any deeper. SPECIFIC INFECTIONS: TINEA CRURIS: Jock itch does not occur over mucous membranes, hence the scrotum is not involved. TINEA CAPITIS: Head TINEA CORPORIS: Trunk TINEA PEDIS: Feet VIRAL INFECTIONS: HERPES SIMPLEX: Group Lesions: Characteristic lesion is groups of vesicles, that may become confluent, but that heal without scarring. VARICELLA-ZOSTER (CHICKEN-POX): Herpetic lesions over dermatomal distribution. HUMAN PAPILLOMAVIRUS (HPV): Causes benign keratinocytic neoplasms. VERRUCA VULGARIS: Common warts, HPV-2,4. Most frequent on dorsum of hands or on face. PLANTAR WARTS: HPV-1, frequently painful and difficult to get rid of. VERRUCA PLANA: HPV-3. Small flat papules on the face. CONDYLOMA ACUMINATUM: Venereal warts HPV-1,6 are the most common causes. HPV-16,18 will lead to squamous carcinoma of cervix. BOWENOID PAPULOSIS EPIDERMODYSPLASIA VERRUCIFORMIS ERYTHEMA INFECTIOSUM (FIFTH DISEASE): Caused by Human Parvovirus B19. MOLLUSCUM CONTAGIOSUM: Caused by the Molluscum Contagiosum poxvirus. ARTHROPOD INFESTATIONS: SCABIES: very itchy lesions, typically between fingers. PATHOLOGY: Little red papules. PEDICULOSIS: ARTHROPOD BITES: PSORIASIS: Persistent, abnormal epidermal squamous-cell hyperplasia. PATHOGENESIS: GENETIC: Psoriasis has a genetic component. The more severe the disease, the more likely it is to be familial. HLA-B13, B17, Bw6 are found commonly and indicate worse prognosis. ENVIRONMENT: Psoriasis is like a hypersensitive response to normal injury (physical, sunlight, chemical), except that it doesn't go away after the injury. Inflammatory neutrophils probably release Epidermal Growth Factor (EGF), which stimulates excessive growth. CELL-PROLIFERATION: Abnormal or unregulated cell-proliferation occurs. There is a decrease in the number of beta-receptors, and decreased levels of cAMP, but the mechanism is unclear. MICROCIRCULATORY CHANGES: Capillary loops in the dermal papillae become venular. Neutrophils are thus attracted to the (venous) vessels, and they accumulate in places where they are not normally found. You see neutrophilic infiltrates in the epidermal layers; normally they remain in dermis. PATHOLOGY: Hypergranulosis: Increased thickness of the granular layer of the epidermis. Parakeratosis: Cell-nuclei of keratinocytes grow all the way up into the cornified layer, where they are not supposed to be. Elongation of Rete Ridges: Excessive proliferation of the basal layer cause it to get thrown into folds. Looks like a "picket fence." Munro Microabscesses: Dense collections of neutrophils in the stratum corneum. SYMPTOMS: Large, erythematous, scaly plaques, commonly on dorsal extensor surfaces. Severity of disease varies. Psoriatic Arthritis (Rheumatoid negative) is often also found. TREATMENTS: Anthralin, topical corticosteroids, systemic methotrexate in severe cases. DYSHESIVE DISORDERS and RELATED DISEASES: PEMPHIGUS VULGARIS: PATHOGENESIS: Type-II (antibody-dependent cellular cytotoxicity) hypersensitivity response against squamous epithelial cells. PATHOLOGY: Desmosomal Dissolution: Antibodies to keratinocytes causes dissolution of desmosomes > epidermis falls apart (acantholysis) Acantholysis: Separation of the stratum spinosum and outer epidermis from the underlying basal epidermis. Acantholytic Cells: Rounded, detached keratinocytes found in the fluid of the bullae. In contrast to erythema multiforme, these are vital epithelial cells. SYMPTOMS / CLINICAL: Bullae: Progressive flaccid bullae resembling a second-degree burn, which can be fatal. Nikolsky's Sign: Sliding thumb across the skin separates the outer layer from the underlying basal cells. TREATMENT: Corticosteroids. EPIDERMOLYSIS BULLOSA: Hereditary group of disorders, in which blisters are formed in response to minor trauma. Underlying defect involves easy separation between the dermis and epidermis. EPIDERMOLYTIC EPIDERMOLYSIS BULLOSA (EB-SIMPLEX) JUNCTIONAL EPIDERMOLYSIS BULLOSA DERMOLYTIC EPIDERMOLYSIS BULLOSA BULLOUS PEMPHIGOID: Autoimmune disease similar to pemphigus, but acantholysis is absent. PATHOGENESIS: Circulating IgG antibodies bind to the BP antigen in the lamina lucida. The antigen is on basal cells that are attached to hemidesmosomes, and binding causes separation of the hemidesmosomes. PATHOLOGY: Complement is activated as a result of Ab-binding. Dermal-epidermal separation in the lamina lucida occurs as a result. This differs from acantholysis (separation within the epidermis), as seen in Pemphigus. DERMATITIS HERPETIFORMS: Intensely pruritic urticaria-like plaques over the extensor surfaces of the body. PATHOGENESIS: Related to gluten-sensitivity in patients with HLA-B8 and HLA-DRw3 haplotypes. The disease can be controlled with gluten-free diet. DISEASES of BASAL KERATINOCYTIC INJURY: ERYTHEMA MULTIFORME: Hypersensitivity reaction to drugs or infectious agents. PATHOGENESIS: Evidence of both Type-III and Type-IV hypersensitivity reactions. Drugs: Sulfonamides, other drugs. Infectious agents: Herpes Simplex, Mycoplasma. PATHOLOGY: Sparse lymphocytic infiltrate into epidermis. Necrosis and pyknosis of individual epidermal cells. SYMPTOMS: Characteristically, both skin and mucous membranes are involved. Peak incidence 20's-30's. Target Lesions: Maculopapular rash with characteristic target-lesions on gross-inspection. The target- lesions may coalesce to form large areas of necrosis. STEVENS-JOHNSON SYNDROME: Dreaded complication, severe form of Erythema Multiforme. TRIAD: Erythema Multiforme Mucous membrane inflammation (conjunctivitis, stomatitis, urethritis, bronchitis) Systemic involvement: fever, headache, malaise May also see (rare): glomerulonephritis, myocarditis, arthritis, encephalitis. LUPUS ERYTHEMATOSUS (SLE): PATHOGENESIS: Involves both Type-III and Type-IV autoimmune reactions. Type-III: Deposition of anti-dsDNA immune complexes at the dermal-epidermal junction. Type-IV: T-Cell reactivity to basal cells. PATHOLOGY / SYMPTOMS: Inflammatory response ------> erythematous plaques > atrophy and scarring of epidermis. Lesions start out hot, edematous, and swollen and end up scarred, shrunken, and contracted. Plaques are typically piecemeal, rather than confluent as we see in Erythema Multiforme. SUBTYPES: CHRONIC CUTANEOUS LUPUS ERYTHEMATOSUS (DISCOID LUPUS): A non-systemic disease only of the skin. PATHOLOGY: Discoid papules with hyperkeratotic margins and a depigmented center. SYMPTOMS: Lesions usually limited to face, scalp, and ears. SUBACUTE CUTANEOUS LUPUS ERYTHEMATOSUS: May see musculoskeletal involvement, but further systemic involvement is rare. SYMPTOMS: Lesions occur in classic photosensitive areas: (1) malar rash, and (2) V-neck area of upper chest. ACUTE CUTANEOUS LUPUS ERYTHEMATOSUS: Full blown disease with systemic involvement. LICHEN PLANUS: Chronic eruption of flat-topped, shiny, violaceous papules on flexor surfaces, male genitalia, and buccal mucosa of unknown cause. PATHOLOGY: It may form linear groups of lesions. Microscopically characterized by a bead-like subepidermal lymphocytic infiltrate. CLINICAL: Spontaneous resolution is common after months to years. INFLAMMATORY DISEASES of VASCULAR BEDS: The most common diseases of the skin occur by allergic reactions. URTICARIA and ANGIOEDEMA: URTICARIA (HIVES): PATHOGENESIS: Type-I immediate-type, IgE-mediated hypersensitivity against a variety of antigens. IgE sticks to Mast Cells and basophils. Subsequent interaction with antigen causes degranulation > local and systemic inflammatory responses. PATHOLOGY: Raised, pale, pruritic papules and plaques that appear and disappear within a few hours. The epidermis remains untouched in a pure urticarial reaction. The reaction is a vasodilation and inflammatory infiltrate (lymphocytes, eosinophils) of the underlying dermis. ANGIOEDEMA: Edema involves the deeper dermis and subcutaneous tissues. DERMATOGRAPHISM: Linear-hives with a rick-pink flare, in which you can write on the lesion and the impression sticks. LEUKOCYTOCLASTIC VASCULITIS: Also known as Cutaneous Necrotizing Venulitis, Hypersensitivity Angiitis PATHOGENESIS: Type-III immune-complex reaction results in elaboration of complement > endothelial damage and fibrin deposition. May be associated with HBV. May occur in conjunction with SLE, RA, ulcerative colitis. PATHOLOGY / CLINICAL: Small-vessel vasculitis showing fibrinoid necrosis of small vessels. Petechial hemorrhages. ALLERGIC CONTACT DERMATITIS (POISON IVY): PATHOGENESIS: Type-IV delayed, cell-mediated hypersensitivity reaction against poison ivy in the epidermis. Antigens are taken up Langerhans cells and presented to T-Cells. PATHOLOGY: Eczematous dermatitis, inflammatory reaction with vesiculation. Epidermal edema is seen, with T-Cell infiltrates. DERMAL CONNECTIVE TISSUE DISEASES: SCLERODERMA (PROGRESSIVE SYSTEMIC SCLEROSIS): EOSINOPHILIA-MYALGIA SYNDROME: PSEUDOXANTHOMA ELASTICUM: SARCOIDOSIS: INFLAMMATORY DISORDERS of PANNICULUS: ERYTHEMA NODOSUM: Septal Panniculitis Without Vasculitis. SYMPTOMS: Self-limited, tender nodules over the extensor surfaces of the lower extremities. PATHOLOGY: Inflammation of subcutaneous tissues around the cutaneous septa. PATHOGENESIS: Triggered by a variety of drugs and bugs, and associated with various diseases. WEBER-CHRISTIAN DISEASE: Lobular Panniculitis Without Vasculitis. ERYTHEMA INDURATUM: Lobular Panniculitis With Vasculitis. ACNE VULGARIS: MELANOCYTIC NEOPLASIA: BENIGN / PRE-MALIGNANT LESIONS: MELANOCYTIC NEVUS (MOLE): Benign, melanocytic neoplasm with symmetric, well-circumscribed margins, with diameter less than 6 mm Lentigo: A freckle. Melanocytes are limited to the basal-cell layer. Junctional Nevus: Melanocytes cluster at the tips of the rete ridges. Compound Nevus: Nests of melanocytes seen in the epidermis and dermis. Dermal Nevus: Intraepidermal melanocytic growth ceases, and melanocytes are confined entirely to the dermis. Skin Tag: Dermal component is terminally differentiated into neuro-mesenchyme, and all that is left is a skin tag. ATYPICAL NEVUS: Nevus with abnormal growth patterns. Cytologic atypia are not found. DYSPLASTIC NEVUS: Malignant nevus with abnormal growth pattern and cytologic atypia. TUMOR PROGRESSION: RADIAL GROWTH-PHASE MELANOMA: Intermediate lesion. A dysplastic nevus, in the dermal epidermal junction, that spreads outward. At this point the lesion is curable by wide excision. VERTICAL GROWTH-PHASE MELANOMA: By definition, a melanoma that has extended into the lower half of the reticular dermis. High-grade lesion with very high chance of metastasis. Cells may appear white or contain no pigment. Dominant site of growth is shifted from the epidermis to the dermis. METASTATIC MELANOMA: Both lymphatic and hematogenous. Every organ may be involved, and widespread, multiple metastases are common. TYPES of MELANOMA: NODULAR MALIGNANT MELANOMA: Very rare, deadly tumor that skips the radial growth phases and arises as an already-anchored malignant tumor in the vertical growth phase. LENTIGO MALIGNANT MELANOMA: Also called a senile freckle. Large, pigmented macule that occurs on sun-damaged skin. Invasion is not as prominent as in superficial spreading melanomas. ACRAL LENTIGINOUS MELANOMA: Most common form of melanoma in dark-skinned persons. SYMPTOMS: Arises in palms, soles, or sub-uncal region. Often presents as a pigmented streak on the nail-bed. They are often picked up late and can metastasize. Hence somewhat worse prognosis. CLINICAL: NUMBER: The greatest single predictor of whether a nevus will be malignant is the number of nevi the patient has. Patients with over 50 nevi on the body tend to develop a melanoma. CLARKE'S STAGING: Growth-Phase of Tumor Stage I: Melanoma in situ, limited to epidermis. Stage II: Radial-Growth-Phase melanoma that has invaded the papillary dermis. Stage III: Vertical-Growth-Phase melanoma that has invaded the reticular dermis. Stage IV: Vertical-Growth-Phase melanoma that has invaded the collagen bundles beneath the reticular dermis. Stage V: Subcutaneous invasion, metastases. ABCD CRITERIA: Things that indicate malignancy. Asymmetry of lesion Borders are irregular Color variation. Can see black, blue, red in the lesion. White can be seen too and is an ominous sign, as it generally means the lesion has already entered vertical growth phase. Diameter is larger than 6 mm. PROGNOSTIC FEATURES: Mitotic Rate: Aside from the growth-phase, it is the most powerful indicator of prognosis. Patients with no mitosis have a greater chance for survival. Lymphocytic Response: An infiltrating, lymphocytic response to the tumor is a good sign. TREATMENT: Melanomas are resistant to chemotherapy and radiation therapy. Once it has metastasized, the prognosis is dismal. OTHER BENIGN LESIONS: CONGENITAL MELANOCYTIC NEVUS: EPITHELIOID-CELL NEVUS (SPITZ TUMOR): BENIGN KERATOSES: Precursor lesions to basal cell and squamous cell carcinomas. SEBORRHEIC KERATOSIS: The benign counterpart to Basal Cell Carcinoma. CLINICAL: Benign, stuck on, sharply demarcated papule or plaque. Lesion looks like it was stuck on the skin and cut out with a cookie cutter. PATHOLOGY: Sheets of squamous cells that resemble basal cells (basal keratinocytes). Horn Cysts: Microscopic structures, indicating a benign lesion. The cells are thought to be derived from hair-follicle germ-cells. The cells resemble Basal Cell Carcinoma, except they do not grow inward (invade), and never metastasize. ACTINIC KERATOSIS: The benign counterpart to Squamous Cell Carcinoma. CLINICAL: Circumscribed, erythematous, scaly patch or plaque, usually on the back of the hand or the face. Sand-paper lesions: They have characteristic sand-paper quality when touched. PATHOLOGY: Abnormal squamous cells begin at the basal layer. As the lesion progresses, atypia progress from the basal layer to the surface. When the abnormal cells stretch from the basal layer to the surface, then you have a carcinoma in situ. Parakeratosis: Keratinization in the lesion is not normal. The keratin layer does not slough off normally and thus accumulates, similar to psoriasis. Thus a plaque forms. TREATMENT: Actinic Keratosis can be reversed by withdrawing UV radiation and sometimes applying cytotoxic treatment. But, it often progresses to squamous cell carcinoma. KERATOACANTHOMA BASAL CELL CARCINOMA: Basal cell carcinoma is the single most common malignant neoplasm in human beings. PATHOGENESIS: Caused by UV-light damage. Very rare or unheard of in black skin, but very common in white skin. CLINICAL: LOCATION: Basal cell tumors very commonly occur in the head and neck region. Less often, they occur on upper body, but almost never on lower body. Pearly white papules are typical lesion, 2-3 mm in diameter. The lesions almost look translucent on the naked skin. The tumors can erode (superficial, central depression) or ulcerate (deeper hole in center). INVASIVE: In the gray-zone between benign and malignant. They almost never metastasize, but they can be very invasive and destructive, so they're called malignant. They can grow downward, right through the dermis, then muscle, and then bone. PATHOLOGY: Multiple nests and elongated fingers of small, very basophilic epithelial cells. Morphea-like Basal Cell Carcinoma: A particularly nasty variant. Pale, tough, scar-like tumor. Tiny nests of basal cells in a very fibrotic stroma. TREATMENT: Electrodesiccation and curettage. SQUAMOUS CELL CARCINOMA: PATHOGENESIS: UV-light induced chromosomal damage. Very rare in black skin. Squamous Cell Carcinoma in situ: Essentially, an actinic keratosis that spans the entire thickness of the epidermis, but does not invade the dermis. There is no clear cut line you can draw between actinic keratosis and squamous cell carcinoma in situ. PATHOLOGY: Raised, hyperkeratotic lesions that may ulcerate if large. The squamous cells regress in maturity. In an advanced SCC, 99% of the squamous cells, throughout the thickness of the skin, show no maturity. SYMPTOMS: Tend to occur on backs of hands or on the face, lips, or ears. THE EYE NORMAL STRUCTURE and FUNCTION: EYELIDS and ORBIT: BLEPHARITIS: CHALAZION: XANTHELASMA: EXOPHTHALMOS: CONJUNCTIVA: Lined by stratified columnar epithelium. HYPEREMIA: HEMORRHAGE: CONJUNCTIVITIS: INFECTIONS: TRACHOMA: Chlamydia Trachomatis Types A, B, and C. EPIDEMIOLOGY: It is the leading cause of blindness worldwide. Prevalent in Asia, Middle East, parts of Africa. PATHOLOGY: Slow, indolent infection of conjunctiva and cornea. Binocular involvement. Primarily lymphocytic infiltrates, involving especially upper conjunctiva. Inflammation leads to scar formation > corneal opacities. Histology: chlamydial inclusions will be visible in the cytoplasm of conjunctival epithelium. OTHER CHLAMYDIAL INFECTIONS Inclusion Blennorrhea: Newborn infected through the birth canal. Purulent conjunctivitis caused by Chlamydia Trachomatis Types D-K. Inclusion Conjunctivitis: Chronic follicular conjunctivitis in adults and older children. OPHTHALMIA NEONATORIUM: N. Gonorrhea or C. Trachomatis infection of the newborn. Silver nitrate drops given prophylactically at birth. DRY EYE SYNDROME: PINGUECULA and PTERYGIUM: PINGUECULA: Conjunctival lump, located nasal to the corneoscleral limbus. PTERYGIUM: Triangular fold of vascularized conjunctiva. It grows horizontally onto the cornea, forming the shape of an insect wing. CORNEA: INJURY: Corneal laceration. Since the cornea is avascular and does not heal, the only cure is a corneal transplant. HERPES SIMPLEX KERATITIS: Inflammation of cornea, primarily HSV-1 but also HSV-2. HSV is the most common cause of corneal ulcers in the U.S. SYMPTOMS: Usually an asymptomatic plaque that heals without ulceration, but ulcerations can occur. Superficial Punctate Keratopathy: Multiple miniature corneal ulcers forming linear, branching fissures. The ulcers heal by scar formation, and corneal opacities result. Fluorescein stain illuminates the ulcers. PATHOLOGY: HSV inclusion bodies are visible microscopically. ONCHOCERCIASIS: Onchocerca Volvulus. Parasite that is the cause of River Blindness. Microfilaria infiltrate many ocular tissues. ARCUS SENILIS: White ring of lipid deposition in the peripheral cornea, occurring with aging. BLAND KERATOPATHY: In hypercalcemia, calcium deposits across the central portion of the cornea. CORNEAL DYSTROPHIES: Hereditary, non-inflammatory disorders of the cornea. EPITHELIAL DYSTROPHIES STROMAL DYSTROPHIES ENDOTHELIAL DYSTROPHIES LENS: CATARACTS: Opacities of the lens. Senile Cataracts: With age, clefts form between adjacent lens fibers, and material accumulates between the clefts. The opacities start at the periphery of the lens and work their way inward. PRESBYOPIA: Age-associated loss of the capacity for accommodation for near vision. PATHOGENESIS: Lens fibers lose their elasticity. They persist indefinitely, with new lens forming on the outside of the old lens fibers, causing the lens to enlarge. UVEA: The choroid, ciliary body, and iris. NORMAL FUNCTION: The uvea provides nutritive support for the retina. It is heavily pigmented, allowing it to absorb light that passes through the retina. UVEITIS: PATHOGENESIS: AIDS: Disseminated fungal infection of the eye. SYMPTOMS: Red eye, photophobia, blurred vision, ciliary flush, constricted pupils (miosis). PATHOLOGY: Keratitic Precipitates: Leukocytes collected on the posterior surface of the cornea. Severe inflammation will disrupt the blood supply to the retina > retinal ischemia. COMPLICATIONS: Posterior Synechiae: Adhesions developing between the iris and the lens. Peripheral Anterior Synechiae: Adhesions between the peripheral iris and anterior chamber angle, which can lead to secondary narrow-angle glaucoma. SYMPATHETIC OPHTHALMITIS: Bilateral granulomatous uveitis secondary to an eye injury. PATHOGENESIS: Believed to be an autoimmune reaction in both eyes, after sensitization to uveal antigens in either eye. CLINICAL: Latency period of 4-6 weeks. Sympathetic Eye: The eye that was not injured. It also gets inflamed at the same time as or shortly after the originally injured (Exciting) eye. PATHOLOGY: Dalen-Fuchs Nodules: Nodules containing reactive RPE, epithelioid cells, macrophages. They appear between Bruch's membrane and the RPE. SARCOIDOSIS: RETINA: HEMORRHAGE: OCCLUSIVE VASCULAR DISEASE: CENTRAL RETINAL ARTERY OCCLUSION: Leads to retinal ischemia, which results in blindness, if the problem isn't corrected very quickly. Cherry Red Spot: Macula remains red while the rest of the retina becomes ischemic. The macula retains blood supply because it gets blood from the choroid underneath. Amaurosis Fugax: Unilateral blurred vision occurring with pinpoint retinal emboli. CENTRAL RETINAL VEIN OCCLUSION: SYMPTOMS: Flame-shaped hemorrhages and edema. Vision may recover surprisingly well. Closed-angle glaucoma is a late sequel to venous occlusion. HYPERTENSIVE RETINOPATHY: PATHOLOGY / CLINICAL: Arteriolar narrowing and focal spasm. Waxy Spots: Due to protein and lipid transudates. In HTN they have a "soft" appearance on funduscope. Cotton Wool Spots: Edematous axonal fibers, due to ischemic injury to nerve fibers. Arteriovenous (AV)-Nicking: Due to sclerosis of the venous walls -- not due to compression by the overlying arteries. Flame-shaped hemorrhages: Hemorrhages in the retinal nerve fiber layer. Copper Wiring: Arteriolar narrowing can decrease visibility of the blood column, making the vessel appear orange rather than red, so-called "copper wiring." STAGES of HYPERTENSIVE RETINOPATHY: Stage I: Mild narrowing Stage II: Focal spasm Stage III: Hemorrhages and exudates Stage IV: Optic disc edema (due to ischemia) and hemorrhage, which can lead to retinal detachment. Malignant Hypertension: In the eye, characterized by necrotizing arteriolitis, with fibrinoid necrosis and thrombosis of the retinal arterioles. RETINAL DETACHMENT: Opening up of the potential space between the retina and the underlying Retinal Pigment Epithelium. This deprives the retina of its only source of nutrient, and permanent blindness results. Rhegmatogenous Retinal Detachment: Associated with retinal tear and with degenerative changes in vitreous. Tractional Retinal Detachment: Retina is pulled toward the center of the eye, as a result of adhesions between the retina and vitreous. CAUSES: Diabetic Retinopathy, Retinopathy of Prematurity, Intraocular Infections Exudative Retinal Detachment: Accumulation of fluid between retina and RPE. CAUSES: Choroiditis, Choroidal Hemangioma, Choroidal Melanoma. TREATMENT: Early retinal detachment can be treated by punching holes in the retina and allowing the fluid to drain. Punctate scars will result, but overall vision will be saved. RETINITIS PIGMENTOSA: PATHOGENESIS: Multiple genetic abnormalities. Accelerated destruction of photoreceptors by the Retinal Pigment Epithelium (RPE) leads to permanent loss of photoreceptors. CLINICAL: Night-blindness and loss of peripheral visual fields. PATHOLOGY: Loss of retinal photoreceptors (rods and cones), and pigment accumulation within the retina. MACULAR DEGENERATION: The most common cause of reduced vision in the U.S. PATHOGENESIS: Age-related. The macula is not vascularized, and nutrients must diffuse through the choroid plexus to supply it. Any loss of diffusion in the choroid will lead to macular ischemia. Drusen: Drusen is metabolic debris that builds up in the macula, underneath the photoreceptor cells. That leads to edema ------> ischemia ------> macular angiogenesis in response > partial retinal detachment (only at macula) and loss of macular vision. CHERRY RED-SPOT of MACULA: Characteristically seen with Tay-Sachs Disease, in which the cherry red spot is the only normal part of the retina. Ganglioside deposits in the ganglion-cells create a pallor around the outside of the red-spot, leaving the red-spot visible. RETINOPATHY of PREMATURITY (RETROLENTAL FIBROPLASIA): Bilateral iatrogenic retinopathy, resulting from hyper-oxygenation in premature infants who suffered from IRDS. DIABETES: DIABETIC RETINOPATHY: PATHOLOGY / PROGRESSION: BACKGROUND RETINOPATHY: Asymptomatic damage to retina Vascular basement membrane thickening Degeneration of pericytes (cells that surrounds vessels) > capillary microaneurysms. Microvascular obstruction > focal retinal infarcts. Waxy Exudates: Capillary microaneurysms increase permeability, leading to waxy exudates. The exudates are yellow and lipid-laden, and have a "hard" appearance in funduscope. PROLIFERATIVE RETINOPATHY: Neovascularization occurs in response to retinal hypoxia. Hemorrhage of newly formed, friable, vessels. Gliosis forms around the neovascularization. Scar formation ------> retina becomes anchored to the vitreous ------> scar contracts > retinal detachment. TREATMENT: Laser treatment DIABETIC IRIDOPATHY: Leads to Glaucoma in Diabetes. DIABETIC CATARACTS: In IDDM, it results from an osmotic effect caused by the accumulation of sorbitol. OPTIC NERVE: PAPILLEDEMA: OPTIC ATROPHY: GLAUCOMA: Optic nerve atrophy, usually resulting from elevated intraocular pressure (IOP), secondary to obstruction of aqueous humor. PATHOGENESIS: Aqueous humor obstruction anywhere along the path of aqueous humor draining > increased intraocular pressure. Lamina Cribrosa: The portion of the sclerae that the optic nerve fibers pass through. In intraocular hypertension, it bows backwards, impinging on the optic nerve fibers and ultimately destroying them. This results in optic nerve atrophy, the ultimate result of prolonged glaucoma. SUBTYPES: CONGENITAL GLAUCOMA (BUPHTHALMOS): Aqueous obstruction caused by congenital anomaly. Buphthalmos: Congenital enlarged eyes. PRIMARY OPEN-ANGLE GLAUCOMA: The most common type of glaucoma in the United States. PATHOGENESIS. Caused by aqueous humor obstruction. Aqueous humor is able to reach the trabecular meshwork unimpeded. Anterior chamber angle of the eye remains normal. IOP is usually increased, but not always. Diabetes and myopia are both risk factors for open-angle glaucoma. PRIMARY CLOSED-ANGLE GLAUCOMA: The iris is displaced anteriorly far enough that it impinges on the trabecular meshwork. The anterior chamber-angle becomes narrow. IOP is always increased. PATHOGENESIS: Chronic uveitis can lead to closed angle Glaucoma, as well as idiopathic. MECHANISM: Pupils Constricted: The iris is relaxed enough that it doesn't obstruct the flow of aqueous humor. Pupils Dilated: The iris is contracted and aqueous humor flow is acutely obstructed, resulting in paroxysmal increased intraocular pressure. ACUTE CLOSED ANGLE GLAUCOMA: If the pupils remain contracted for a prolonged period of time, this leads to an acute emergency. Hypotensive treatment must start immediately or else sight will be lost. Patient experiences severe pain. SECONDARY GLAUCOMA: Secondary to inflammation, hemorrhage, adhesions. LOW-TENSION GLAUCOMA: Glaucoma without increased intraocular pressure. Lamina Cribrosa Defect: In some people, there is a primary defect in the lamina cribrosa such that it bulges under normal pressure ------> impinge on optic nerve fibers > optic atrophy without any increased IOP. PATHOLOGY: Optic Nerve Cupping seen on funduscopic exam. Optic Nerve Atrophy results from prolonged intraocular hypertension. Increased IOP leads to bowing of the lamina cribrosa ------> impinges on optic nerve fibers > optic nerve atrophy Ganglion-cell layer degeneration: Ganglion cells of the retina degenerate, impairing vision. CLINICAL: Peripheral vision is lost first, followed by central vision. Patient therefore may not notice visual loss in early glaucoma. In severe cases of glaucoma, you may see central retinal artery occlusion. MYOPIA: Nearsightedness. The focal point of light occurs in front of the retina. Correct with diverging lens. PHTHISIS BULBI: Non-specific, end-stage eye, characterized by atrophy of the eyeball. NEOPLASMS: UVEAL MELANOMA: The most common primary tumor of the eye. PATHOLOGY: The tumor arises from uveal melanocytes. They tend to arise in the posterior part of the eye, behind the RPE. Hence they are not easily visible. As they grow they can cause retinal detachment. SYMPTOMS: They can cause hemorrhage, cataracts, glaucoma, retinal detachment, inflammation. Heterochromia: Variegation in color of the eye, with involvement of the iris. Metastases is hematogenous -- not lymphatic. It often metastasizes to the liver. TREATMENT: Enucleation of the eye. RETINOBLASTOMA: Tumor of retinal cells occurring in children. PATHOGENESIS: Defects in the Retinoblastoma (Rb) tumor suppressor gene cause the tumor. Familial Retinoblastoma: Binocular retinoblastoma, caused by a defect on chromosome 13. Only one more mutation is then required ("two-hit hypothesis") to cause the tumor in each eye. Sporadic Retinoblastoma: More common, uniocular. Mutations in both Rb genes are required to cause a sporadic tumor to develop. PATHOLOGY: It's a little-blue-cell tumor. Rosettes: Blue cells form rosettes, as they do with other little-blue-cell tumors. SYMPTOMS: Fatal if untreated. Survival is high with enucleation of eye. No red reflex will be seen on fundoscopic exam. This can help in early detection. Prognosis: The prognosis correlates with how far the tumor has traveled along the optic nerve. The further it has traversed along the optic nerve, the worse prognosis. Metastasis: Exophytic tumors can metastasize to the brain: Retina ------> vitreous > trabecular meshwork > brain.