Eye Pathology: Clinicopathologic Correlations

Key questions

1. Q1What are the three coats of the globe?

   Outer fibrous coat (cornea + sclera), middle vascular coat = uvea (iris, ciliary body, choroid), inner neural coat (retina + RPE).
2. Q2Why does the uvea matter for pathology?

   It is pigmented and highly vascular: the site of uveal (choroidal, ciliary body, iris) melanoma and of blood-borne metastases (lung, breast).
3. Q3Which retinal layers matter most for reading hemorrhage shapes?

   Nerve fiber layer (fibers run parallel to the surface → flame/splinter hemorrhages) vs the deeper nuclear/plexiform layers (vertical columns → dot-blot hemorrhages). The outer plexiform layer is where edema and lipid (hard exudate) collect.
4. Q4What is a retinal detachment anatomically?

   Separation of the neurosensory retina from the retinal pigment epithelium (RPE) — the plane of the embryonic optic vesicle cavity, a potential space.
5. Q5What is the blood supply of the retina?

   Inner retina: central retinal artery (branch of the ophthalmic artery). Outer retina (photoreceptors): diffusion from the choriocapillaris.
6. Q6Where is the macula/fovea and why is it vulnerable?

   Temporal to the disc; the fovea has only cones and no inner layers; the macula collects fluid easily (macular edema) and gives central, fine vision.

Key questions

1. Q7What causes retinal hemorrhages, edema and exudates?

   Diabetes, hypertension, vasculitis/infection, radiation retinopathy, blood disorders (leukemia, sickle cell). They share one pattern of microvascular injury.
2. Q8A 58-year-old with no known history has hemorrhages and exudates. Next step?

   All of the above: check glucose, check blood pressure, work up vasculitis/infection and ask about head and neck radiation.
3. Q9What is the DDx of optic neuropathy by disc appearance?

   Cupping = glaucoma. Pallor = non-glaucomatous atrophy (ischemic, compressive, etc.). Swelling = papilledema (raised ICP) or other causes (severe hypertension, infiltration by leukemia, metastasis, sarcoid).
4. Q10What is the DDx of an intraocular mass?

   Adult: choroidal melanoma (most common primary), nevus, metastasis (lung, breast), leukemic/lymphomatous infiltrate. Child: retinoblastoma.
5. Q11What is the DDx of proptosis?

   Graves disease (most common), idiopathic orbital inflammation (pseudotumor), tumor (primary or metastatic), infectious orbital cellulitis, systemic inflammation/vasculitis (sarcoidosis, GPA).

Key questions

1. Q12How important is diabetic retinopathy?

   It is the #1 cause of blindness from ages 24 to 63.
2. Q13What are the two main causes of permanent vision loss in DR?

   Macular edema and traction retinal detachment.
3. Q14What is the main cause of acute vision loss in DR?

   Vitreous hemorrhage (from fragile new vessels).
4. Q15What is the pattern of injury?

   Endothelial/pericyte damage → microaneurysms, hemorrhage and leaking vessels → edema (macula especially prone) → lipid precipitates (hard exudates).
5. Q16What is a hard exudate?

   Yellow, waxy lipid/protein precipitate left behind when leaked edema fluid resorbs; collects in the outer plexiform layer, often ringing the macula.
6. Q17What separates non-proliferative from proliferative DR?

   Proliferative DR has neovascularization (new vessels grow into the vitreous) driven by ischemia/VEGF; non-proliferative has microaneurysms, hemorrhages, exudates and edema only.
7. Q18What vignette labs fit PDR?

   Long-standing DM with CKD and cardiovascular disease; HbA1c elevated (e.g., 9.6%).

Key questions

1. Q19What drives retinal neovascularization?

   Retinal ischemia from capillary closure → VEGF and other angiogenic factors → new, fragile vessels.
2. Q20Where do the new vessels grow?

   Into the vitreous cavity, NOT within the retina, on the retinal surface and optic disc.
3. Q21What are the consequences?

   Fragile vessels bleed (vitreous hemorrhage) and scar (fibrovascular membranes) → traction retinal detachment, the end stage of proliferative DR.
4. Q22Which diseases cause it?

   Diabetes (most common), sickle cell disease (peripheral "sea fan"), retinal vein occlusion, retinopathy of prematurity, radiation. The pattern applies beyond diabetes.
5. Q23A 30-year-old woman with abdominal pain and normal glucose has peripheral neovascularization. Diagnosis?

   Sickle cell anemia (pain crisis + peripheral neovascularization + normal glucose).
6. Q24What is a cotton wool spot and how does it relate?

   A "soft exudate": a nerve fiber layer micro-infarct with swollen axons (cytoid bodies). A nonspecific sign of microvascular ischemia (DM, HTN, vasculitis, radiation, leukemia) that usually does not cause major vision loss.

Key questions

1. Q25What is retinal detachment?

   Separation of the neurosensory retina from the RPE, with fluid in the subretinal space.
2. Q26How does it present?

   Sudden, painless loss of part of the visual field ("a shade or curtain pulled across"), often preceded by flashes and floaters.
3. Q27What are the three mechanisms?

   Rhegmatogenous (a retinal tear lets fluid in — myopia, trauma, aging vitreous), tractional (fibrovascular scar pulls — PDR, sickle cell) and exudative/serous (fluid under an intact retina — tumor such as melanoma, severe HTN, inflammation).
4. Q28A diabetic with worsening vision suddenly loses the upper half of the field. Mechanism?

   Traction retinal detachment from proliferative diabetic retinopathy (upper field lost = inferior retina detached).
5. Q29How can a uveal mass cause RD?

   A choroidal melanoma lifts the overlying retina (exudative detachment) → a "curtain" field defect.
6. Q30What happens to a detached retina histologically?

   Photoreceptors lose their blood supply from the choriocapillaris and degenerate; the RPE can proliferate. Early reattachment preserves vision.

Key questions

1. Q31What is papilledema?

   Optic disc swelling caused specifically by raised intracranial pressure, usually bilateral.
2. Q32How is it related to "optic nerve swelling"?

   Papilledema is one cause of optic nerve swelling. Swelling is the broader finding; papilledema is the ICP-driven subset.
3. Q33What else swells the optic nerve?

   Severe (malignant) hypertension and infiltration of the nerve by tumor or granuloma (leukemia, metastases, sarcoidosis); also optic neuritis and ischemic optic neuropathy.
4. Q34Why does raised ICP swell the disc?

   The subarachnoid space extends along the optic nerve sheath; high CSF pressure blocks axoplasmic flow → axons swell at the disc.
5. Q35How does papilledema affect vision early?

   Vision is often preserved early (enlarged blind spot, transient obscurations); chronic papilledema leads to atrophy.

Key questions

1. Q36What does optic atrophy look like?

   A pale optic disc — the sign of non-glaucomatous atrophy (lost axons and capillaries, gliosis).
2. Q37What are its causes?

   Ischemic (anterior ischemic optic neuropathy, giant cell arteritis), compressive (pituitary adenoma, meningioma, orbital mass, Graves), inflammatory (optic neuritis/MS), chronic papilledema, trauma, toxic/nutritional and hereditary (e.g., Leber hereditary optic neuropathy).
3. Q38How is glaucomatous atrophy different?

   Glaucoma causes cupping — an enlarged, excavated cup from axon loss — rather than a flat pale disc.
4. Q39Pathologically, what is glaucomatous cupping?

   Loss of ganglion cell axons with posterior bowing of the lamina cribrosa; usually tied to raised intraocular pressure.

Key questions

1. Q40Which intraocular malignancy is most common in adults?

   Choroidal (uveal) melanoma — the most common primary intraocular malignancy in adults; the eye is the second most common site of primary melanoma after skin.
2. Q41Where in the uvea can melanoma arise?

   Choroid (most common), ciliary body and iris — the uveal tract extends anteriorly to the iris.
3. Q42What are the key pathologic prognostic factors?

   1) Basal diameter (not height); 2) scleral (extraocular) invasion; 3) cytology of the cells; 4) chromosome 3 loss/molecular changes. Color is NOT important.
4. Q43How does cytology change prognosis?

   Callender classification: spindle cells = more favorable, epithelioid cells = worse, mixed = intermediate. Unlike cutaneous melanoma, cytology matters.
5. Q44How are nevi different from melanoma?

   Nevi are more common, have more benign cytology, and are usually flat and stable.
6. Q45What are Lisch nodules?

   Pigmented iris hamartomas — a variant of iris nevus — important for diagnosing neurofibromatosis type 1.
7. Q46How can you tell metastasis from amelanotic melanoma?

   Metastases (lung, breast) are often multiple, bilateral, amelanotic and occur in a patient with a known cancer; pigment alone does not separate them — histology does.
8. Q47How does uveal melanoma spread?

   Hematogenously (no lymphatics in the uvea) — mainly to the liver.

Key questions

1. Q48What is retinoblastoma?

   The most common primary intraocular malignancy in children — potentially very lethal.
2. Q49How does it present?

   Most commonly leukocoria (white pupillary reflex) and strabismus.
3. Q50What are the prognostic factors?

   1) Tumor size and vitreous seeding; 2) optic nerve invasion (route to the brain); 3) extrascleral invasion; 4) tumor histology (differentiation).
4. Q51What are Flexner-Wintersteiner rosettes?

   Tumor cells ringed around a central empty lumen — specific for retinoblastoma (photoreceptor differentiation).
5. Q52What are Homer-Wright rosettes?

   Tumor cells around a central tangle of fibrillary neuropil, with no lumen — seen in retinoblastoma and also neuroblastoma, medulloblastoma and PNET.
6. Q53What are fleurettes?

   A "bouquet of flowers" of cells recapitulating photoreceptors — the most differentiated pattern and a good prognostic sign.
7. Q54What is the genetics?

   Loss of both copies of RB1 (13q14). Hereditary: germline mutation, bilateral, earlier onset, risk of osteosarcoma. Sporadic: unilateral, later.
8. Q55What does the gross tumor look like?

   White, friable mass with calcification and necrosis; may grow into the vitreous (endophytic) or under the retina (exophytic).

Key questions

1. Q56What is proptosis (exophthalmos)?

   Forward protrusion of the globe from increased orbital contents — the orbit is a closed bony box open only in front.
2. Q57A 35-year-old man has bilateral diplopia, swelling and irritation, plus palpitations, sweating and weight loss. Diagnosis?

   Graves disease (thyroid eye disease) — the most common cause of proptosis.
3. Q58What is the pathology of Graves orbitopathy?

   Enlarged extraocular muscle bellies (inferior and medial rectus most affected; tendons spared) with lymphocytic infiltration, GAG deposition, edema and later fibrosis; orbital fat also expands.
4. Q59What is idiopathic orbital inflammation (orbital pseudotumor)?

   Non-specific, non-infectious inflammation and fibrosis of orbital tissue, with no systemic cause — painful proptosis that responds to steroids; a diagnosis of exclusion.
5. Q60How is infectious orbital cellulitis recognized histologically?

   Acute inflammation (neutrophils) and pus; clinically fever, pain on eye movement, often spread from ethmoid sinusitis.
6. Q61What is the most common primary orbital malignancy in adults?

   Lymphoma (usually B-cell, MALT type).
7. Q62What is the most common malignant primary orbital tumor in children?

   Rhabdomyosarcoma. It arises from orbital soft tissue, NOT from the extraocular muscles; histology ranges from primitive cells to cells with skeletal-muscle cross-striations.
8. Q63Why can so many tumor types occur in the orbit?

   Many tissues live there — nerves, optic nerve, fat, soft tissue, muscles, lacrimal gland — plus invasion from sinuses, nasopharynx and cranial cavity, and metastases. Histology is often needed.