PATHOLOGY - Diseases Flashcards
Which virus is the most common cause of conjunctivitis? Which subtype?
Adenovirus (DNA) –> mostly belong to subgroup D (A-F classification) –> usually type 8, 19 and 37 –> type 8 is classic cause of EKC
Where are psammoma bodies found?
In meningiomas
What is the difference between type 1 HIV and type 2 HIV?
Type 1 - urban centre areas, homosexuals and IVDUs
Type 2 - Africa, heterosexually transmitted
What are the different serotypes of chlamydia ? what are they responsible for?
A B C - trachoma
D E F G H I J K - genital chlamydia and adult inclusion conjunctivitis
L1 - L3 : lymphogranuloma venereum
Which cell type is responsible for inflammatory corneal damage?
polymorphonuclear leukocyte (PMN)s release hydrolytic enzymes that denature protein and cause tissue necrosis
What is the pathogenesis of Sjogren’s syndrome? (3) Which antibody is associated with Sjogren’s?
- Lymphocytic and T-cell infiltration affecting conjunctival, oral and lacrimal acinar glands
- Loss of conjunctival goblet cells and squamous metaplasia and keratinisation in conjunctival epithelium
- Impaired secretion of saliva and tears (aqueous component of tear film) - dry eyes/mouth
Antibody: Anti-Rho and Anti-La
What is the immunological pathophysiology behind of rheumatic eye disease?
T-cell and immune complex mediated vasculitis
What are the ocular features of rheumatic eye disease? (5)
- Peripheral corneal ulceration
- Corneal melt (MMP release)
- Macula oedema
- nectrotising scleritis
- posterior nodular scleritis
- scleromalacia perforans
What is the triad in Behcet’s disease?
- Oral aphthous ulcers (98%)
- Genitcal ulcers (80%)
- Ocular disease (70)% - panuveitis with hypopyon
What is the HLA-associated of Behcet’s? What age is most common? What race does it affect predominantly?
- HLA-B51
- 20s-40s
- East Asia and Mediterraneans
What is the ocular manifestations of Behcet’s disease?
Sudden onset aggresive panuveitis with hypopyon.
- Non-granulomatous, necrotising vasculitis with posterior segment complications; BRVO, CMO, vitritis and neovascularisation
What are large vessel disease vasculitis?
What are medium vessel disease vasculitis?
What are small vessel disease vasculitis?
LARGE: GCA, Takayasu
MEDIUM: Polyarteritis nodosa, Kawasaki
SMALL: Wegener’s, Churg-Strauss, Henoch Schonlein Purpura
What is sympathetic ophthalmia?
Bilateral granulomatous inflammation of the uvea (panuveitis) following injury to one eye, typically involving uveal incarceration in the sclera.
What is the pathophysiology / ocular manifestations of sympathetic ophthalmia
- Sensitation of ocular antigens leads to uveitis by MHC Class II CD4 T cells
- Uveal thickening by macrophage infiltration
- Small granulomas (epithelioid giant cells) between Bruch’s and RPE - Dalen Fuch’s nodules (small discrete yellowish infiltrates)
What is the immunological pathophysiology of giant cell arteritis?
- Local dendritic cells recruit CD4 T cells causing activated macrophages, giant cells, smooth muscle cells recruitment for vascular remodelling
- Inflammatory infiltrate includes (1) macrophages (2) multinucleated giant cells (located near fragmented elastic lamina) (3) lymphocytes (4) plasma cells
What vessels are affected in GCA?
Fibrin thrombus obstructs vessel lumen
Central retinal artery, ophthalmic artery and cerebral arteries. Arterioles are not affected as they do not possess an elastic layer
What is the cause of granulomatosis with polyangiitis (Wegener’s)? What antibodies are associated with this
Granulomatosis inflammation and necrosis
Antibodies: c-ANCA (anti-neutrophil, anti-cytoplasmic antibody)
What is the viral aetiology/pathogens commonly associated with ARN? (4) What is the immune status of the patient generally?
- VZV
- HSV
- CMV
- EBV
Usually immunocompetent patients
What are the clinical phases in ARN?
- Acute phase
- Episcleritis/scleritis
- Granulomatous uveitis
- Vitritis
- Retinitis (peripheral)
- Viral inclusion bodies seen on light microscopy - Late cicatricial
- Retinal tears and detachment
- PVR
What is the difference between progressive outer retinal necrosis and ARN? (3)
- Usually impacts immunocompromised patients vs immunocompetent patients in ARN
- Typically minimal intraocular inflammation, AC and vitreous involvement in ARN, not in PORN.
- Large well-defined white retinal patches which can be peripheral or central
What is VKH? What are the epidemiological factors in VKH?
Typically viral illness prodome followed by Bilateral granulomatous panuveitis.
Affects young adults (second and fifth decades), moreso females and heavily pigmented patients
What are the HLA associations with VKH?
HLA-DR1 and HLA-DR4
What are the two clinical phases phases in VKH? What is the immunological pathophysiology?
- Acute granulomatous phase
- chronic non-granulomatous phase
- Uveal thickening
- Lymphocyte infiltration
- Epithelioid collections
- Dalen-Fuch’s nodules (granulomas/macrophages between RPE and Bruch’s) - also seen in sympathetic ophthalmia
What are the systemic findings in VKH? (5)
Dermatological - Alopecia, Vitiligo, Poliosis
Non-dermatological - sensorineural deafness, headache
What are the immunological manifestations of sarcoidosis (4)
Sarcoid nodules contain…
1. non-caseating epithelioid histiocytes (granulomas)
2. multinucleated giant cells (granulomas)
3. asteroid bodies
4. Schaumann bodies
What are the ocular manifestations of sarcoidosis (6)
- Mutton-fat KPs
- Trabecular meshwork (Berlin) nodules
- Vitreous opacities/snowballs (string of pearls)
- Multifocal chorioretinal lesions
- Peri-phlebitis
- Optic disc nodules/granulomas
- Tented peripheral synechiae
What are the sight threatening complications of thyroid eye disease (2)
- Dysthyroid optic neuropathy
- Corneal exposure
It is tendon sparing inflammation
What is the immunological pathogenesis of thyroid eye disease? (5)
- TSH-receptor antibodies react with orbital fibroblast antigens which have increased IGF-1 receptors –> inflammatory activation
- Extraocular muscle perivascular lymphocyte infiltration, tendon sparing swelling in MRI
- Accumulation of GAGs in extracellular matrix
- Fibroblasts produce mucopolysaccharides which attract water to cause swelling
- Patchy infiltration of lymphocytes, monocytes, mast cells and fibroblasts (NOT MACROPHAGES)
What is homocysteinuria? Dominant or recessive?
Reduced levels of cystathione beta-synthetase, affects methionine
Recessive.
What are the clinical features and ocular pathophysiology of homocystinuria?
- Lens dislocation - metabolic abnormality of zonules with thick band of PAS-positive material of the surface of ciliary processes and pars plana
- Thromboembolic risk
What are the ocular manifestations of cystinosis?
Abnormal transport of cystine –> birefringent crystals.
Cystine crystals in cornea, retina, choroid, RPE, retina, conjunctiva
What causes corneal arcus?
Plasma lipids leak from blood vessels and are deposited into corneal stroma
What causes xanthelasma? Which rare conditions is associated with this
Lipid containing macrophages which deposite in the dermis of the eyelid
Erdheim-Chester disease - systemic disease associated with xanthelasma and lipoid granulomas
What causes pinguecula and pterygium?
Sun exposure –> elastic fibre degeneration –> elastic material deposition in the conjunctiva –> thickening and hyalinisation of conjunctival stroma –> bulbar nodules (pinguecula) and pterygium which encroaches on the cornea
What are the immunological / pathophysiological manifestations of pterygium?
- Predominantly basophils and fibroblast proliferation
- Absent cystic spaces
- Stocker’s line - line of iron at advancing edge
- Elasttic degeneration at limbus in interpalpebral fissure
What is the pathophysiology behind macula degeneration? Which complement factor is affected?
Fibrous metaplasia of RPE cells leading to collagen deposition following choroidal neovascular leakage and haemorrhage.
Associated with complement factor H gene.
What are the nutrients found in the AREDS study to reduce progression of AMD? (7)
- Zinc
- beta-carotene
- Vitamins C & E
- B Vitamins
- Lutein
- Zeaxanthin
- Omega-3
What are the two different types of calcification on the cornea? What is their cause
- Metastatic calcification in hypercalcaemia –> band keratopathy which is calcium deposition in Bowman’s layer - removed in EDTA therapy
- Dystrophic calcification in damaged/degenerating tissues seen in phthisis bulbi
What is amyloid? What are its two stains?
Insoluble fibrillar glycoprotein deposited in blood vessels and basement membrane as extracellular eosinophilic hyaline material
- Congo Red - stains Apple green birefringent
- H&E - stains pink (eosin)
What are the ocular manifestations of amyloid? (2)
- Drusen in AMD
- Corneal Lattice dystrophy
What are the systemic associations of amyloid (6)
Which are light chain amyloids?
- myeloma (monoclonal plasma cell proliferation)
- Alzheimer’s (prealbumin)
- Thyroid carcinoma (polypeptide hormones)
- Chronic inflammation in RA (serum AA protein)
- Waldenstrom’s macroglobulinaemia
- Mediterranean fever
Light chain
1. Waldenstrom macroglobulinaemia
2. MUltiple myeloma.
What is the pathophysiology behind pseudoexfoliation syndrome?
white deposits on lens/ciliary process/ iris surface and inner TM –> sampaoeli’s line on gonioscopy
Granular eosinophilic material with elastin and fibrillin produced by abnormal basement membranes of aging epithelial cells accumulate in trabeculum, lens capsule, iris and ciliary body.
More common in females
What are the epidemiological factors of pigment dispersion syndrome? (2)
- Commoner in caucasians
- Increased risk in myopia due to concavity of mid-peripheral iris which increases contact between peripheral iris and zonules –> mechanical friction and pigment release
What are cotton wool spots?
Microinfarctions which cause swollen axonal endings in the retinal nerve fibre layer
What are hard exudates? Where does it form?
Eosinophilic masses containing foamy macrophages - formed when underperfusion damages vascular endothelium leading to plasma leakage in outer plexiform layer.
What are microaneurysms?
pericyte necrosis secondary to ischaemia which leads to weakening of capillary wall –> bulges or blowouts. These are gradualy filled by basement membrane deposits.
What are the different types of haemorrhages? Where do they occur?
Flame haemorrhage : arteriole rupture within blood tracking the nerve fibre layer
Dot haemorrhage: capillary rupture within outer plexiform layer
Blot haemorrhage: capillary bleeding between photoreceptors and RPE
What causes neovascularisation generally in the eye?
Ischaemia –> growth from venous side of capillary bed. Vasoformative factors diffuse through vitreous, PC and PC and induce rubeosis iridis and neovascular glaucoma.
What is the pathophysiology behind diabetic retinopathy? (5)
- Loss of pericytes (contractile cells that wrap aroudn capillaries and are embedded in BM)
- thickening of capillary basement membrane of ciliary processes
- Degeneration of capillary endothelial cells
- Breakdown of inner blood-retinal barrier with leakage to cause formation of exudates, microaneurysms
- Vacuolation of iris pigment epithelium
What is the pathophysiology of Coat’s disease? What are the ocular manifestations? Is it unilateral or bilateral?
Affects males predominantly –> Abnormal arterial and venous endothelium –> leakage of lipid-rich plasma into retinal and subretinal space
UNILATERAL –> Causes exudative retinal detachment and vascular abnormalities
What is the pathogenesis of cataract?
- Lens crystallins break down to albuminoids in response to aging and UV radiation
- Tyrosine is released and converted to adrenaline and melanin
- Lens pigemtnation progresses from yellow to brown then to black
What are the causes of secondary cataract?
- Metabolic disturbance
- Radiation
- Trauma
These all disrupt lens epithelial ionic transport mechanisms causing disorgainsation of lens proteins
What is the genes involved in pathophysiology of primary open angle glaucoma? (3)
- Myocilin gene (MYOC) on chromosome 1 encodes myocilin involved in trabecular meshwork contractility
- Optineurin gene on chromosome 10 involved in exocytosis
- ELAM-1 (endothelial leukocyte adhesion molecule) is present which indicates stress response in trabecular meshwork
What is the pathophysiology of primary open angle glaucoma? (3)
- Increased IOP –> pressure induced ischaemia due to occlusive disease of posterior ciliaries and direct mechanical pressure preventing axoplasmic flow through lamina cribrosa
- Prelaminar optic nerve becomes atrophic (macula and papillomacular bundle are spared)
- The cup enlarges vertically more than horizontally
What is the pathophysiology of primary closed angle glaucoma? (4)
- Lens thickening leads to displacement of pupillary part of iris by anterior lens surface
- Leads to shallowing of AC and pressure build up behind iris
- Iris bombe –> peripheral iris pushing towards TM
- Acute pressure increased leads to blocked axoplasmic flow
What is the pathophysiology / immunological process behind secondary open angle glaucoma? (4)
- Inflammatory cells
- Tumour cells
- Haemorrhages
- Lens matter and macrophages following degenerative rupture of the lens capsule
- Phacolytic glaucoma - open angle, pseudohypopyon
- Phacoanalphylactic (phaco-antigenic): autoimmune granulomatous reaction following rupture of the capsule
What are the possible mechanisms behind secondary closed angle glaucoma? (5)
- Anterior lens displacement by tumour
- Anterior and posterior synechiae in uveitis
- Rubeotic glaucoma - fibrovascular proliferation in angle due to retinal ischaemia
- Malformation of the angle in congenital glaucoma
- phacomorphic glaucoma - lens-induced due to mature cataract formation leads to pupillary block
What are the main causes of uveitis (6)
- Idiopathic
- Seronegative arthropathies
- JIA
- Herpes
- Sarcoidosis
- SLE
What gene is usually reponsible for some epithelial and stromal corneal dystrophies ?
- TGF-B gene in 5q31 chromosome (dominant)
This is expressed on epithelial and keratocyte membranes and regulates wound healing
What are the 7 different epithelial corneal dystrophies?
- Cogan’s microcystic/ map-dot fingerprint dystrophy - microcysts and fingerprints in whorl like pattern.
- Meesman’s dystrophy - mutation in KRT3 gene, tiny epithelial cysts.
- Labrador keratopathy - crystalline deposits with clear vacuoles on epithelium.
- Lisch epithelial dystrophy - X -linked whorl like epithelial lesions of clear vacuoles
- Gelatinous drop like dystrophy - TACSTD2 gene - gelatinous deposits resembling mulberries
- Epithelial recurrent erosion dystrophy - defect adhesions of epithelial cells to basement membrane.
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