Pathology: AIIMS NOV 2015

Q-1. In genomic imprinting, DNA undergoes
a) Methylation
b) Acetylation
c) Deamination
d) Phosphorylation

Answer: Methylation
Explanation:
Genomic imprinting is the epigenetic phenomenon by which certain genes are expressed in a parent of origin-specific manner.
Genomic imprinting is an inheritance process independent of the classical Mendelian inheritance.
It is an epigenetic process that involves DNA methylation and histone modifications (Methylation, acetylation and phosphorylation) without altering the genetic sequence.

Q-2. There are different check points in cell growth and regulation. Which one is the primary point for regulation of cell growth?
a) End of G1
b) Start of G2
c) End of S1
d) End of M

Answer: End of G1
Explanation:
Passage through a checkpoint from one cell cycle phase to the next requires a coordinated set of proteins that monitor cell growth and DNA integrity.
The G1/S checkpoint:
Controls progression of cells through the restriction point ® into the DNA synthesis S-phase
Most important regulator of cell cycle
Checks for DNA damage before replication
The G2/M checkpoint:
Prevents cells containing damaged DNA from entering mitosis (M)
Monitors the completion of DNA replication
The spindle checkpoint:
Ensures proper chromatid attachment prior to progression from metaphase to anaphase
Important point:
On exposure of ionizing radiation, cell cycle arrests in G2 and repair mechanism is activated.

Q-3. Identify the crystal in the urine analysis

a) Oxalate
b) Uric acid
c) Phosphate
d) Cysteine

Answer: Oxalate
Explanation:
Shape of crystal present in urine:
Calcium oxalate: Enveloped shaped
Uric acid: Brown lemon shaped or star shaped and birefringent with polarized light
Triple phosphate: Rectangular shape

Q-4. Absent urobilinogen in urine with icterus indicates
a) Peri-hepatic obstruction
b) Hemolysis
c) Hepatitis
d) Liver failure

Answer: Peri-hepatic obstruction
Explanation:
Urine urobilinogen:
Hemolytic anemia: Increased
Hepatitis: Decreased in Cholestatic hepatitis
Obstructive jaundice: Absent

Q-5. For which procedure is the following instrument used?
a) Bone marrow examination
b) Liver biopsy
c) Pleural biopsy
d) Lumbar puncture

Answer: Bone marrow examination
Explanation:
Bone marrow aspiration needle
The safe and preferred sites for bone marrow aspiration:
The posterior superior iliac crest (Most common site employed)
The anterior superior iliac crest
The sternum
The tibia in infant younger than 1 year
Important point:
The tibial location is not utilized in older patients because the marrow cellularity is not consistent.

Q-6. In the following histopathology of schwannoma, the arrow marked lesion shows?

a) Antony A with Verocay body
b) Rosettes
c) Antony B with Verocay body
d) Palisading

Answer: Antony A with Verocay body
Explanation:
Microscopic features of Schwannoma:
Circumscribed and often encapsulated
Composed of uniformly spindled Schwann cells with Antoni A (cellular fascicular) and Antoni B (myxoid; vacuolated) regions
Verocay bodies (eosinophilic cores and nuclear palisading)
Cells are spindled with ill defined cytoplasm, dense chromatin