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Past General Pathology Questions And Disscussion
1. All of the following are true regarding fixing of tissue during histologic examination except
- Kills all organisms
- Done using 2% formalin
- Tissue hardness
- Fixing tissue prevents autolysis
ANSWER b
- The most commonly used fixative in histology is formaldehyde.
- It is usually used as a 10% neutral buffered formalin (NBF), that is approx. 3.7%–4.0% formaldehyde in phosphate buffer, pH 7. Since formaldehyde is a gas at room temperature, formalin – formaldehyde gas dissolved in water (~37% w/v) – is used when making the former fixative.
- Formaldehyde fixes tissue by cross-linking the proteins, primarily the residues of the basic amino acid lysine.
- Its effects are reversible by excess water and it avoids formalin pigmentation.
- Paraformaldehyde is also commonly used and will depolymerize back to formalin when heated, also making it an effective fixative.
- Other benefits to paraformaldehyde include long term storage and good tissue penetration.
- It is particularly good for immunohistochemistry techniques.
- The formaldehyde vapor can also be used as a fixative for cell smears.
2. Which of the following test is used to compare the chromosomes between normal and neoplastic cells or for detecting genetic transfer of diseases
- Western blotting
- PCR
- Southern blotting
- Comparative genomic hybridization
ANSWER d
- Comparative genomic hybridisation (CGH) is a technique that permits the detection of chromosomal copy number changes without the need for cell culturing.
- It provides a global overview of chromosomal gains and losses throughout the whole genome of a tumour.
- Tumour DNA is labelled with a green fluorochrome, which is subsequently mixed (1:1) with red labelled normal DNA and hybridised to normal human metaphase preparations.
- The green and red labelled DNA fragments compete for hybridisation to their locus of origin on the chromosomes.
- The green to red fluorescence ratio measured along the chromosomal axis represents loss or gain of genetic material in the tumour at that specific locus.
- In addition to a fluorescence microscope, the technique requires a computer with dedicated image analysis software to perform the analysis.
- This review aims to provide a detailed discussion of the CGH technique, and to provide a protocol with an emphasis on crucial steps.
3. Retinoblastoma spreads by
- Optic nerve invasion
- Vascular/hematogenous invasion
- Lymphatic invasion
- Direct tissue invasion
ANSWER a
Retinoblastoma is an eye cancer that begins in the retina — the sensitive lining on the inside of your eye. Retinoblastoma most commonly affects young children, but can rarely occur in adults
- A rare form of eye cancer, retinoblastoma is the most common form of cancer affecting the eye in children. Retinoblastoma may occur in one or both eyes.
- Retinoblastoma occurs when nerve cells in the retina develop genetic mutations.
- Alterations in RB1 or MYCN can give rise to retinoblastoma.
- These mutations cause the cells to continue growing and multiplying when healthy cells would die. This accumulating mass of cells forms a tumor.
- Retinoblastoma cells can invade further into the eye and nearby structures. Retinoblastoma can also spread (metastasize) to other areas of the body, including the brain and spine.
- Tumor cells that have invaded the optic nerve and leptomeninges and then disperse into the circulating subarachnoid fluid are characteristic of the second pattern of metastasis.
- This may occur even when there is no tumor detected at the cut end of the optic nerve. Via the circulating subarachnoid fluid, tumor cells can also reach the spinal cord, distant sites of brain, and the contralateral optic nerve.
4. A 60year old male patient has hypertension and signs of renal failure biopsy of his fibrinoid degeneration in walls of renal blood vessels the most probable diagnosis blood vessels the most probable diagnosis
- Hyaline arteriosclerosis
- Thrombangitis obliterans
- Hyperplastic arteriosclerosis
- Arteriosclerosis obliterans
ANSWER c
Hyperplastic arteriolosclerosis:
It is characterized by thickening of the arteriolar wall due to the concentric
proliferation of smooth muscle cells, giving the arterioles an “onion skin”
appearance.
These changes represent an adaptive response of arterioles to severe (“malignant”)
hypertension.
5. Oral and dermal manifestations are seen in which type of leukemia?
- Aleukemic leukemia
- Monocytic leukemia
- Lymphocytic leukemia
- Myelocytic leukemia
ANSWER b
Monocytic leukemia is a type of myeloid leukemia characterized by a dominance of monocytes in the marrow. When the monocytic cells are predominantly monoblasts, it can be subclassified into acute monoblastic leukemia.
Signs and symptoms of acute myelogenous leukemia include:
- Fever
- Bone pain
- Lethargy and fatigue
- Shortness of breath
- Pale skin
- Frequent infections
- Easy bruising
- Unusual bleeding, such as frequent nosebleeds and bleeding from the gums
