Clinical Pathology Question and Answers
Question 1. Write a note on fine needle aspiration cytology.
Answer:
Fine needle aspiration cytology
- It is a diagnostic procedure used to investigate lumps or masses
- Performed by using a thin (22–25 gauge) needle
- A needle is inserted into a mass or nodule and the tissue cells are aspirated with or without the application of suction
- Aspirated tissue is smeared on a slide
- These slides are now stained with May-Grunewald Giemsa and Pap stain and are evaluated under the microscope to make a diagnosis
Read and Learn More Preparatory Manual of Pathology Question and Answers
Question 2. Write a note on exfoliating cytology.
Answer:
In exfoliating cytology, cells shed from the body surfaces are collected and examined
How are the cells collected?
1. Spontaneous exfoliation
- Done in the cases of peritoneal fluid, pleural fluid, pericardial fluid, urine, cysts, washings (peritoneal, bladder), where the cells spontaneously shed into these washings are examined
2. Mechanical exfoliation
- Cells are manually scraped/brushed off the surface
- Done in cervical Pap smear and brushing (bronchial, gastric, biliary, oral, etc)
Note:
- A brushing sample should be taken before a biopsy as the latter results in bleeding and will obscure the brushing cell’s morphology
Question 3. Write a note on erythrocyte sedimentation rate (ESR).
Answer:
Erythrocyte sedimentation rate (ESR)
- Measures the rate of settling (sedimentation) of erythrocytes
Comprises three stages
- Stage 1: Formation of rouleaux in which RBCs stack together like a pack of coins (10 minutes)
- Stage 2: Stage of sedimentation: In which rouleaux settle down (40 minutes)
- Stage 3: Packing of the rouleaux (10 minutes)
Factors affecting ESR
1. Factors increasing ESR
- Old age, pregnancy, anemia, elevated fibrinogen, macrocytosis, high temperature
2. Factors decreasing ESR
- Microcytosis, low fibrinogen, polycythemia, leukocytosis Methods for estimation
- Westergren method
- Wintrobe method
- Zeta sedimentation ratio
- Micro-ESR method
Question 4. Write a note on proteinuria.
Answer:
- A normal kidney can excrete up to 150 mg/24 hours of protein in the urine
- Proteinuria: Protein excretion in urine greater than 150 mg/24 hours in adults
Causes of proteinuria
- Glomerular proteinuria: Can be selective (albumin and transferring) and nonselective (large molecular weight proteins)
- Tubular proteinuria: Seen in acute pyelonephritis, chronic pyelonephritis, tuberculosis, heavy metal poisoning, interstitial nephritis, transplant rejection
- Overflow proteinuria: Seen in multiple myeloma (Bence Jones proteins), intravascular hemolysis (hemoglobin)
- Hemodynamic proteinuria: Transient and seen in patients with high fever, hypertension, heavy exercise, heart failure, seizures
Question 5. Write a note on the significance of the casts in urine.
Answer:
Renal casts
- Cylindrical, cigar-shaped structures, formed in the distal renal tubules and collecting ducts
- Casts are specifically of renal origin
- Composed of a precipitate of a protein secreted by the tubules (Tame-Shortfall protein)
Two main types
- Non-cellular: Hyaline, granular, waxy, fatty
- Cellular: Red blood cell, white blood cell, renal tubular epithelial cell
Important points
- Waxy casts: Seen in end-stage renal failure
- Fatty casts: Seen in nephrotic syndrome
- Broadcasts: Seen in chronic renal failure and renal tubular obstruction, associated with poor prognosis
- Red cell casts: Indicate acute glomerulonephritis
- White cell casts: Indicates pyelonephritis
- Renal tubular epithelial cell casts: Seen in acute tubular necrosis, heavy metal poisoning, allograft rejection
Question 6. Mention the significance of ketone bodies in urine.
Answer:
- Excretion of ketone bodies, acetoacetic acid, beta hydroxyl butyric acid, and acetone in urine is termed ketonuria
- Ketones are the breakdown products of fatty acids
- Normally, ketone bodies are not detectable in urine, however, in individuals in whom fat is used as a source of energy, this fat breakdown is responsible for the excessive production of ketone bodies
Conditions associated
- Decreased utilization of carbohydrates as seen in diabetes mellitus with ketoacidosis
- Decreased availability of carbohydrates: Seen in starvation, persistent vomiting
- Glycogen storage disorders: on Gierke’s disease
- Increased metabolic needs: Fever, thyrotoxicosis, pregnancy
Question 7. Mention four indications of bone marrow aspiration.
Answer:
Indications for bone marrow aspiration
- Unexplained cytopenias
- Suspected acute leukemia for classification and categorization
- Suspected chronic myeloproliferative disorders
- Suspected myelodysplasia syndromes
- Metastatic tumors in the marrow
- Investigation of pyrexia of unknown origin
- Suspected storage disorders like Gaucher’s disease or Neumann-Pick disease
- Suspected infections like kala-azar, military tuberculosis, or histoplasmosis
Indications for bone marrow biopsy
- Dry tap as seen in myelofibrosis or leukemia
- Suspected aplastic anemia
- Suspected myelofibrosis
- Suspected hairy cell leukemia
- Staging of lymphoma
Question 8. Write a note on the Bombay blood group.
Answer:
Bombay blood group
- H-gene produces a transferase enzyme
- Transferase changes precursor substance into H substance on the RBC surface
- H-substance is converted into A and B antigens by A and B genes (present on chromosome 9) on the RBC surface
- Some individuals do not inherit the H gene (genotype hh) and thus cannot synthesize the H substance
- Such individuals may inherit A or B genes but cannot express them as they are not converted to A and B antigens
- These individuals are said to have Bombay phenotype or Bombay blood group
- They lack H, A, and B antigens, and their red cells type as group O
- It is an extremely rare blood group and is not compatible with any of the blood groups on crossmatching
Question 9. Write a note on blood components prepared in a blood bank.
Answer:
Blood components
- Red cells: Packed red cells, leucocyte—poor red cells, washed red cells, frozen red cells, irradiated red cells
- Platelets: Platelet concentrate, apheresis platelets
- Granulocyte concentrate
Plasma components
- Fresh frozen plasma
- Cryoprecipitate
Question 10. Discuss the principle of crossmatching.
Answer:
Crossmatching
- Aim: To prevent the transfusion of incompatible red cell units
- Two types: Major crossmatch and minor crossmatch
- Major crossmatch: Testing the recipient serum against donor red cells
- Minor crossmatch: Testing the donor serum against recipient red cells
Note:
- Minor crossmatch is not important and therefore, only the red blood cells from the donor unit are tested against the recipient’s serum
- For transfusion of platelets or fresh frozen plasma, crossmatching is not required
Question 11. Write a note on reticulocyte count concerning its procedure and interpretation.
Answer:
Reticulocytes
- Are young RBCs containing remnants of RNA and ribosomes
- Recognized by supra vital stains which detect RNA in these cells
- RNA appears as blue precipitating granules within RBCs
- Supra-vital staining refers to the staining of these cells in a living state
Principle
- A few drops of blood are incubated with methylene blue solution, which stains granules of RNA in red cells
Reagent
A new methylene blue solution is prepared as follows:
- New methylene blue: 1gm
- Sodium citrate: 0.6 gm
- Sodium chloride: 0.7 gm
- Distilled water: 100 ml
The reagent should be kept stored in a refrigerator at 2–6 degrees Celsius and filtered before use
Other dyes used include: Brilliant Cresyl Blue and Azure B
Sample
- EDTA blood sample
Method
- In a test tube, take 2–3 drops of filtered new methylene blue solution
- Add an equal amount of blood and mix well
- Keep the mixture at room temperature for 15 minutes
- Prepare a smear from the small drop of a mixture prepared above
- The slide should be viewed under an oil immersion lens in a microscope
- Reticulocytes show deep blue precipitates in the red blood cells
Result
- The number of reticulocytes is expressed as a percentage of red cells
Reference range
- Reticulocyte percentage: 0.5 – 2.5%
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