Day 13 (2): Practical Ocular Pathology Flashcards
What are the components of a properly submitted specimen?
- Preserved in a generous amount of 10% formalin IMMEDIATELY after extraction
- completely submerged for at least 24 hours to allow formalin to seep through the entire tissue
- halts degradation of tissue - Include pertinent clinical history & diagnosis
- name and age
- history of the submitted specimen
- clinical impression with possible differentials
- intraoperative findings - Obtain the entire lesion as much as possible with good margins showing the transition between the normal and abnormal tissue for purposes of comparison
- Must be labelled appropriately for orientation
- include descriptors like superior, inferior, nasal and temporal
What are the parts of the gross examination of a specimen?
A. Ascertain anatomic landmarks
- determine whether L or R specimen
- clue: posterior aspect of globe
1. Posterior ciliary arteries: horizontal plane
2. EOM attachment: SO & IO insert temporally
3. Optic nerve: attached nasally
B. Measure diameters (L x W x H)
C. Gross description
- shape
- smoothness
- color
- texture
- appearance
- integrity of adjacent structures
D. Documentation (photos)
- for presentation purposes, always communicate with the pathologist to obtain good specimen photos
E. Cutting proper
- obtain a representative sample:
1. Pupil-optic nerve axis: along the horizontal axis; most representative as it includes all the structures in the eye
2. Thickest and tallest part of the mass
- describe cut section
F. Paraffin fixing and staining
- grossly cut specimen is fixed in paraffin & cut into smaller serial slices using a microtome
- serial cuts are arranged and fixed on a slide prior to staining
- if specimen is too large, it may be cut into 3 - 4 smaller cuts and fixed on separate slides BUT do NOT forget to label appropriately
Note:
1. Conjunctival specimen
- place flat on a piece of filter paper, fold and submerge entirely in formalin
- Exenteration specimen
- include even lids, lashes and orbital tissues
What are the stains routinely used for ocular tissues?
Most commonly used stains:
1. Hematoxylin & Eosin (H & E) stain
2. Periodic acid-Schiff (PAS) stain
Others:
1. Corneal deposits: Masson’s Trichrome
2. Melanomas: Bleached stain
What is the Hematoxylin-Eosin Stain?
Combination of two stains:
1. Hematoxylin = BLUE/DARK-PURPLE
- basic dye that stains acidic structures
- stains DNA (nuclei), RNA (ribosomes) and calcified material
- Eosin = PINK
- acidic dye that stains basic structures
- stains the cytoplasm, ECM and proteins
Structures are classified according to the color they take on:
1. Basophilic: mostly blue
2. Eosinophilic/Acidophilic: mostly pink
3. Amphophilic: combination of both
4. Chromophobic: clear
Note: Melanin-containing structures
- stains BROWN
or black
What is the Periodic acid-Schiff Stain?
- used to detect:
1. Polysaccharides (glycogen, cellulose)
2. Mucosubstances (glycoprotein, glycolipids, proteoglycans, mucin) - structures containing a high proportion of carbohydrates stain MAGENTA/PURPLE
1. Collagen (connective tissues, cartilage)
2. Mucus
3. Glycocalyx, Glycogen
4. Basement membranes
5. Cell walls of LIVING fungi (glucans, chitin)
What is Masson’s Trichrome?
- three-color stain used for distinguishing cells from surrounding connective tissue
- used to identify deposits in corneal dystrophies
Results:
1. RED: keratin, muscle, cytoplasm, RBCs
2. BLUE/GREEN: collagen, bone
3. BROWN/BLACK: nuclei, basophilic structures
What is Immunostaining?
- takes advantage of the unique immunohistochemical characteristics of cells to ascertain hard to identify tissues
- works even on formalin-fixed and paraffin-imbedded specimen
- Cytokeratin: epithelial cells
- Neural-specific enolase: neural tissues
- Actin/myosin: muscle
- Leukocyte common antigen: lymphoid tissue
Discuss pathologic findings in retinoblastoma.
- most common intraocular pathology
- most common indication for enucleation
- usually presents in the advanced stage
- suspected in any intraocular tumor with CALCIFICATIONS in a young child
- include surrounding normal tissues in cuts for comparison
- include AT LEAST 10 mm of ON tissue for prognostication
Pathologic Features:
- small round cells with hyperchromatic nuclei and scanty cytoplasm arranged like rosettes with minimal to absent intervening stroma
- Flexner-Wintersteiner rosettes
- rings of cells surrounding an empty lumen
- characteristic but not mandatory to dx - Homer Wright pseudorosettes
- ring of cells with an eosinophilic fibrillary center - Fleurettes
- retinoblastoma cells that have undergone greater photoreceptor differentiation
Prognostic considerations:
1. choroidal invasion
2. scleral extension
3. optic nerve involvement
- above three factors affect prognosis of the disease and determine need for possible adjuvant chemo-radiation
Treatment:
1. Enucleation –> Exenteration
2. Adjuvant chemo-radiation
- widespread choroidal or scleral invasion
- optic nerve involvement
Discuss pathologic findings in Malignant Melanoma.
- round mushroom-shaped, heavily pigmented intraocular mass
- composed of epithelioid and spindle-shaped cells with hyperchromatic nuclei with cytoplasmic melanin pigments
- more commonly seen in elderly caucasians
What happens in Sympathetic Ophthalmia?
- bilateral, granulomatous uveitis caused by exposure of previously immune-privileged ocular antigens from trauma or surgery with a subsequent bilateral autoimmune response to this tissue
- may be observed after an iatrogenic or traumatic break in the lens capsule
- at around 9th week AOG, the embryonic and fetal lens contained in the nucleus has already been sequestered by the capsule long before the immune system develops
- accidental exposure will be recognized as foreign causing the immune system to mount a response, inadvertently damaging not just the intraocular structures in the affected eye but also attacking the SYMPATHIZING eye
Management of Trauma Cases:
1. Repair ASAP
2. Enucleate immediately if repair is not possible to spare the other eye
Discuss the common pathologies of the conjunctiva.
PTERYGIUM
- non-pigmented conjunctival mass encroaching on the cornea
- elastin fibers in the subconjunctival layer breakdown due to UV damage
- DDX: SCC, Verruca
- Elastotic degeneration of the elastic fibers
- Neovascularization
- Fibrosis
SQUAMOUS CELL CARCINOMA
- similar in appearance to pterygium but with a soapy-looking tissue overlying the lesion
Signs of malignancy:
1. Acanthosis: hyperproliferation of hyperchromatic basophilic poorly-differentiated cells beyond the normal 3 - 5 layers of the epithelium
2. Mitotic figures: highly proliferative
3. Keratin pearls/keratinization: metaplasia
4. Evidence of invasion:
- beyond the BM of the conjunctival epithelium
- into the corneal stroma or sclera
5. Feeder vessel: vascular tissue
MALIGNANT MELANOMA
- spindle-shaped cells with prominent hyperchromatic nuclei and mitotic figures
- pigmentation due to melanin pigments
- (+) feeder vessel
- ectodermic in origin in contrast to choroidal melanoma of mesodermic origin
- DDX: Nevus
How to determine if the iridocorneal angle is open or closed in a specimen?
A vertical line drawn along the angle should also bisect the 1st and 2nd ciliary processes
Pseudo-Angle
- if not bisecting any ciliary process
How to determine if the iridocorneal angle is open or closed in a specimen?
A vertical line drawn along the angle should also bisect the 1st and 2nd ciliary processes
Pseudo-Angle
- if not bisecting any ciliary process
How to determine if angle closure is primary or secondary?
Primary ACG
- there are no structures pulling the iris forward or pushing it from behind
Secondary ACG
- peripheral anterior synechiae: adhesions between the TM and the iris
- posterior synechiae: adhesions between the iris and the lens
- cataractous lens: disorganized cellular layers
What are the pathologic findings observed in Glaucoma?
- Hypocellularity of the GCL
- Optic nerve head cupping
- Thinning of the neuroretinal rim
- Posterior displacement or bowing of the lamina cribrosa
