MDS PREP
Leukaemia should be high on a list of differential diagnosis when which of the following is noted?
1. Spontaneous bleeding
2. Persistent headache
3. Epigastric pain
4. Chronic or acute arthralgia
Oral Pathology
Answer: 1
Spontaneous bleeding is a key indicator for considering leukemia in differential diagnosis.
Progenitor hematopoietic stem cells originate in -
1) Bone Marrow
2) Thymus
3) Lymph node
4) Spleen
General Pathology
Answer: 1
Progenitor hematopoietic stem cells originate in the bone marrow, where they differentiate into various blood cell lineages.
The opsonins which leads to phagocytosis is/are:
1. lgG (Fc fragment)
2. C3b of complement cascade
3. 1gM (Fc fragment) and C5b of complement cascade
4. A and B
Pathology
Answer: 4
Opsonins are molecules that enhance the phagocytosis of antigens by binding to their surfaces and acting as markers or labels that make them more recognizable to phagocytes.
1. lgG (Fc fragment): Immunoglobulin G (IgG) is the most common antibody isotype
in human serum. It plays a crucial role in the secondary immune response. The Fc
region of IgG is the fragment that interacts with Fc receptors present on the
membrane of phagocytic cells. When an antigen is coated with IgG, the Fc
fragments of these antibodies can bind to the Fc receptors, leading to the
activation of the phagocytic process. This is known as antibody-dependent
phagocytosis, where the antibody acts as an opsonin to facilitate the
recognition and engulfment of the antigen by phagocytic cells.
2. C3b of complement cascade: The complement system is a cascade of proteins
that can be activated in response to an infection or the presence of foreign
substances. C3 is a central protein in this system, and when it is cleaved into
C3a and C3b, the latter can bind directly to antigens. C3b acts as an opsonin by
coating the surface of pathogens. The presence of C3b on a microbial surface
allows it to be recognized by complement receptors on phagocytic cells, such as
macrophages. This interaction enhances the efficiency of phagocytosis, as the
receptors can recognize the bound C3b and engulf the antigen more readily.
3. IgM (Fc fragment) and C5b of complement cascade: While IgM is the first
antibody isotype produced in response to an infection and can also opsonize
antigens, it is less efficient than IgG due to its pentameric structure and
lower affinity for phagocytic receptors. However, it is not as commonly
associated with phagocytosis as IgG. Regarding C5b, it is part of the membrane
attack complex (MAC) and is involved in the direct destruction of pathogens
rather than acting as a classical opsonin that leads to phagocytosis. The MAC
assembles on the surface of the antigen and creates pores, leading to osmotic
lysis and destruction of the cell membrane.
Carcinoma of lip
1. Occurs mostly in males
2. Metastases easily
3. Occurs mostly in the lower lip
4. Is mostly basal cell type
Oral Pathology
Answer: 1
Carcinoma of the Lip
Occurs mostly in males: Lip carcinoma, particularly
squamous cell carcinoma, is more common in males than females. This is often
attributed to higher rates of tobacco and alcohol use, as well as increased
sun exposure without protection.
Metastases easily: While lip carcinomas can
metastasize, they do not typically do so as easily as other cancers.
Squamous cell carcinoma of the lip can metastasize, but it is often
localized initially.
Occurs mostly in the lower lip: This is true; the lower
lip is the most common site for lip carcinoma due to greater sun exposure
and thinner skin.
Is mostly basal cell type: This statement is
misleading. While basal cell carcinoma is the most common skin cancer
overall, squamous cell carcinoma is more prevalent in the lip region.
A malignant tumour cell moves through the stages of:
1. Progression ¨ vascularization ¨ invasion ¨ detachment ¨ embolization
2. Vascularization ¨ invasion ¨ prepression ¨ detachment ¨ embolization
3. invasion¨ vascularization¨progression ¨ detachment ¨ embolization
4. Detachment ¨invasion ¨ vascularization ¨ progression ¨ embolization
Pathology Answer: 1
The correct answer is: 1. Progression ¨ vascularization ¨ invasion ¨
detachment ¨ embolization.
Explanation of the stages for a malignant tumor cell:
1. Progression: This is the initial stage of tumor development where the cells
acquire the ability to proliferate in an uncontrolled manner. This can be due to
genetic mutations that alter the normal regulatory mechanisms that control cell
division. The tumor grows locally within the tissue or organ of origin.
2. Vascularization: Also known as angiogenesis, this stage involves the
formation of new blood vessels that supply the tumor with nutrients and oxygen,
which is essential for its continued growth and progression. The tumor cells
secrete factors that stimulate the growth of blood vessels into the tumor mass.
3. Invasion: The malignant tumor cells develop the capability to invade
surrounding tissues. They secrete enzymes that degrade the extracellular matrix
and basement membrane, allowing them to move through these barriers and invade
neighboring tissues and organs.
4. Detachment: During this stage, tumor cells detach from the primary tumor
site. This is facilitated by the loss of cell-to-cell adhesion molecules and the
degradation of the extracellular matrix by proteolytic enzymes.
5. Embolization: Detached tumor cells can then enter the lymphatic system or
bloodstream. This process is known as intravasation. They travel through these
vessels as emboli and can potentially form new tumors at distant sites, which is
the process of metastasis.
The extracellular polysaccharide synthesized by cariogenic streptococci in the presence of excess sucros is best described as
1) Mucopolysaccharide
2) Dextran-like glucan
3) Glycogen-like glucan
4) Amylopectin
Oral Pathology
Answer: 2
Cariogenic streptococci, particularly Streptococcus mutans, synthesize extracellular polysaccharides when exposed to high levels of sucrose. These polysaccharides are primarily dextran-like glucans, which are formed from the polymerization of glucose units. Dextran contributes to the formation of dental plaque and biofilm, facilitating the adherence of bacteria to tooth surfaces and promoting caries development.
Acanthosis is
1. Increase in mitotic division
2. Increase in thickness of superficial layer
3. Increase in thickness of spinous layer
4. Disruption of basal lamina
Oral Pathology
Answer: 3
Acanthosis refers to the hyperplasia or
thickening of the stratum spinosum layer of the epidermis or epithelium. It is
often seen in conditions such as psoriasis or lichen planus. This is distinct
from other phenomena like increased mitotic division or disruption of the basal
lamina.
Hereditary spherocytosis is due to deficiency -
1) Spectrin
2) Invertin
3) Cytokeratin
4) All of the above
General Pathology
Answer: 1
Hereditary spherocytosis is primarily due to a deficiency of spectrin, a protein that helps maintain the integrity of the red blood cell membrane.