FMGE 2025 - Pathology Practice Questions

Q: In Myasthenia gravis, which of the following is the primary target of autoantibodies at the neuromuscular junction?

Post-synaptic ACh Receptor. ***Post-synaptic ACh Receptor*** - Myasthenia gravis is an autoimmune disorder where **IgG autoantibodies** are produced against the nicotinic **acetylcholine receptors (AChR)** on the post-synaptic muscle membrane [1], [2]. - These antibodies block acetylcholine from binding and also cause **complement-mediated destruction** and accelerated degradation of the receptors, leading to fatigable muscle weakness [1]. *Presynaptic ACh receptor* - Presynaptic acetylcholine receptors are involved in modulating the release of acetylcholine, but they are not the primary target of autoantibodies in Myasthenia Gravis. - Conditions targeting presynaptic components, like **Lambert-Eaton Myasthenic Syndrome**, involve a different pathophysiology. *Voltage-gated calcium channels at NMJ* - Autoantibodies against presynaptic **P/Q-type voltage-gated calcium channels (VGCCs)** are the hallmark of **Lambert-Eaton Myasthenic Syndrome (LEMS)**, not Myasthenia Gravis. - The blockade of these channels impairs the presynaptic release of acetylcholine, leading to a distinct clinical picture of weakness that often improves with activity. *Acetylcholinesterase* - **Acetylcholinesterase** is the enzyme that breaks down acetylcholine in the synaptic cleft; it is not the target of autoantibodies in this disease [3]. - **Acetylcholinesterase inhibitors**, such as pyridostigmine, are a primary treatment for Myasthenia Gravis because they increase the availability of acetylcholine at the neuromuscular junction [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 213-214. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1237-1238. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1238-1239.

Q: A patient had a road traffic accident (RTA). NCCT head was normal on admission. The patient later died after several days in the ICU due to coma. Brain biopsy revealed multiple punctate hemorrhages. What is the diagnosis?

Diffuse axonal injury. ***Diffuse axonal injury*** - This condition is caused by **traumatic shearing forces** due to sudden acceleration-deceleration, as seen in RTAs, leading to widespread axonal damage [1][2]. - A key feature is a discrepancy between clinical severity (e.g., coma) and initial imaging, as non-contrast CT scans are often normal [2]. The presence of **multiple punctate hemorrhages** on biopsy or sensitive MRI sequences (like the one shown) is characteristic [2]. *Ischemic injury* - This results from reduced blood flow causing a stroke, not direct trauma, and presents with focal neurological deficits corresponding to an arterial territory [3]. - Pathologically, it leads to **liquefactive necrosis** in a specific vascular distribution, not diffuse punctate hemorrhages [3]. *Intraventricular bleeding* - This refers to hemorrhage within the ventricular system and would be clearly visible as a **hyperdensity** on an initial NCCT head scan [3]. - It is a distinct type of intracranial bleed and does not present as microscopic, diffuse parenchymal hemorrhages [3]. *Subdural hemorrhage* - This involves bleeding into the space between the dura and arachnoid mater, usually from torn bridging veins. - It appears as a **crescent-shaped** hyperdensity on a CT scan and is typically evident immediately after trauma. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 700-701. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 701-702. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 706-707.

Q: What defect is seen in Bernard Soulier syndrome?

Deficiency of GpIb receptors. ***Deficiency of GpIb receptors***- **Bernard-Soulier syndrome (BSS)** is an autosomal recessive disorder caused by defective or deficient **Glycoprotein Ib (GpIb)** [1]; this receptor is necessary for platelet adhesion to the subendothelium via **von Willebrand factor (vWF)** [1], [2]. - This defect results in dysfunctional primary **hemostasis**, causing bleeding and characteristic findings like **giant platelets** (macrothrombocytopenia) and mild to severely prolonged **bleeding time**. *Deficiency of GpIIb/IIIa receptor*- Deficiency or dysfunction of the **GpIIb/IIIa receptor** (fibrinogen receptor) causes **Glanzmann thrombasthenia** [1], which impairs platelet aggregation, not initial adhesion. - In Glanzmann thrombasthenia, platelets fail to aggregate in response to most agonists (like ADP or thrombin), but the initial adhesion mediated by GpIb is preserved [1]. *Deficiency of von Willebrand factor*- Deficiency of **von Willebrand factor (vWF)** causes **von Willebrand disease (vWD)**, the most common inherited bleeding disorder. - vWF is the ligand that links GpIb on the platelet to the exposed collagen in the vessel wall [2]; its deficiency is distinct from the receptor deficiency seen in BSS. *Deficiency of ADP receptors*- Deficiency of **ADP receptors** (specifically the P2Y12 receptor) impairs the signal transduction critical for sustained platelet aggregation and granule release [2]. - While affecting primary hemostasis, this congenital receptor deficiency is separate from BSS and is rarely reported; the most common interference with this receptor is therapeutic (**clopidogrel**). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 668-669. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, p. 128.

Q: A skin graft was performed on an immunocompromised patient using tissue from another immunocompromised individual. Weeks later, the patient developed contractures and systemic symptoms. What is the most likely cause?

Graft-versus-host disease. ***Correct: Graft-versus-host disease (GVHD)*** - GVHD occurs when **immunocompetent donor T lymphocytes** from the graft recognize recipient tissues as foreign and mount an immune attack [1] - Key scenario: **Immunocompromised recipient** receiving tissue from another person (even if donor is immunocompromised, donor T cells in the graft can still be functional) - The recipient's compromised immune system **cannot eliminate donor lymphocytes**, allowing them to engraft and attack host tissues [1] - **Contractures** are characteristic of chronic GVHD affecting skin and connective tissue - **Systemic symptoms** (fever, diarrhea, hepatitis) reflect multi-organ involvement typical of GVHD - Timeline of **weeks** fits both acute (2-100 days) and chronic (>100 days) GVHD *Incorrect: Delayed wound healing* - Would present as local wound complications, not systemic symptoms - Does not explain contractures or multi-organ involvement - Typically occurs within days, not weeks *Incorrect: Rejection due to recipient T8 cells* - This describes **host-versus-graft** (rejection), not graft-versus-host - Patient is **immunocompromised**, so recipient T cells are impaired and unlikely to mount effective rejection - Would cause graft loss, not systemic symptoms in the recipient *Incorrect: Graft failure* - Non-specific term that doesn't explain the clinical presentation - Would present as loss of graft function/wound dehiscence, not systemic symptoms - Does not account for contractures or multi-organ disease **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 244-245.

Q: Tau protein inclusions are involved in:

Alzheimer’s disease. ***Alzheimer's disease*** - **Tau protein** aggregation leads to the formation of **neurofibrillary tangles (NFTs)**, which are characteristic pathological hallmarks of Alzheimer's disease, particularly in the hippocampus and cortex [1]. - Hyperphosphorylation of Tau causes it to dissociate from microtubules, destabilizing the neuronal cytoskeleton and ultimately leading to **synaptic dysfunction** and cell death [2]. *Huntington's disease* - This disorder is caused by an expansion of a **CAG triplet repeat** in the *HTT* gene, leading to the accumulation of misfolded **Huntingtin protein**. - It is characterized by atrophy of the **caudate nucleus** and putamen (striatum) and is not primarily linked to Tauopathies. *Amyotrophic lateral sclerosis* - ALS is primarily characterized by the aggregation of **TDP-43** (Tar DNA-binding protein 43) in motor neurons, a distinct type of proteinopathy. - While some cases of ALS overlap with Frontotemporal Dementia (FTD) which can involve Tauopathies, classic ALS pathology is defined by **TDP-43 inclusions**. *CNS lymphoma* - CNS lymphoma is a **primary central nervous system (CNS) tumor**, usually a non-Hodgkin B-cell lymphoma. - Diagnosis relies on identifying atypical lymphoid cells and is not associated with misfolded Tau protein inclusions, which are features of **neurodegenerative diseases** [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1292-1295. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 721-722. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1288-1289.

Q: For testing blood clotting/coagulation parameters, blood is collected in which color-coded vacutainer tube?

Blue. ***Blue*** - The blue-coded vacutainer contains **Sodium Citrate** (3.2% or 3.8%), which is the required anticoagulant for performing coagulation studies, such as **PT** (Prothrombin Time) and **aPTT** (Activated Partial Thromboplastin Time) [1]. - **Sodium Citrate** works by binding and sequestering **calcium ions** (Factor IV), thereby reversibly preventing the coagulation cascade from proceeding until calcium is added back in the lab [1]. *Red* - The Red top tube typically contains **no anticoagulant** (or a clot activator) and is used to obtain **serum** after the blood clots naturally. - It is utilized for chemistry, serology, and blood bank tests, where the natural clotting process is required or coagulation factors are not needed. *Green* - The Green top tube contains **Heparin** (Lithium or Sodium Heparin), which inhibits clotting by augmenting the activity of **antithrombin III** [2]. - Although it provides plasma, it is unsuitable for routine coagulation assays because heparin itself significantly interferes with most coagulation factor tests. *Gray* - The Gray top tube contains **Potassium Oxalate** as an anticoagulant and **Sodium Fluoride** as a preservative. - It is specifically reserved for **glucose** and sometimes **lactate** measurements, as sodium fluoride inhibits enolase, thereby preventing glycolysis (glucose breakdown) by blood cells. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 128-130. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 583-584.

Q: Which of the following is pro-apoptotic?

Bax. ***Bax*** - Bax is a key **pro-apoptotic** effector protein from the Bcl-2 family [1]. Upon activation by stress signals, it translocates to the mitochondria and forms pores in the outer membrane [2]. - This pore formation, along with Bak, leads to **Mitochondrial Outer Membrane Permeabilization (MOMP)**, which releases **cytochrome c** and initiates the intrinsic caspase cascade of apoptosis [3]. *Bcl-2* - Bcl-2 is the prototypical **anti-apoptotic** protein that prevents apoptosis by binding to and inhibiting pro-apoptotic proteins like Bax and Bak [2]. - By preventing MOMP, it maintains mitochondrial integrity and is often overexpressed in cancers, such as follicular lymphoma, contributing to cell survival [2]. *Bcl-xL* - Bcl-xL is another major **anti-apoptotic** protein in the Bcl-2 family, with a function very similar to Bcl-2 [2]. - It promotes cell survival by sequestering pro-apoptotic BH3-only proteins and preventing the activation of Bax and Bak. *Mcl-1* - Mcl-1 (Myeloid cell leukemia-1) is a critical **anti-apoptotic** protein that is essential for the survival of various cell types [2]. - Its primary role is to inhibit apoptosis by neutralizing pro-apoptotic proteins, and its high levels are often associated with tumor progression and resistance to chemotherapy [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Cellular Responses to Stress and Toxic Insults: Adaptation, Injury, and Death, pp. 65-67. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 310. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Cellular Responses to Stress and Toxic Insults: Adaptation, Injury, and Death, pp. 64-65.

Question 1

A 30-year-old female presents to the OPD with a 3 cm breast lump in the upper medial quadrant. The lump has an uneven, bosselated surface, and the overlying skin is mildly ulcerated. Microscopic examination reveals the given findings. What is the most likely diagnosis?

Accepted Answer

Phyllodes tumor

Answer

Fibroadenoma

Answer

Paget's disease

Answer

Galactocele

Question 2

A patient presents with weight gain, thinning of hair, and dry skin. Diagnosis is Hashimoto’s thyroiditis. Which antibody is seen in this case?

Accepted Answer

Anti-TPO antibody

Answer

Anti TBG

Answer

Long-acting thyroid-stimulating antibody

Answer

Anti-TSH receptor antibody

Question 3

In Myasthenia gravis, which of the following is the primary target of autoantibodies at the neuromuscular junction?

Accepted Answer

Post-synaptic ACh Receptor

Answer

Acetylcholinesterase

Answer

Voltage-gated calcium channels at NMJ

Answer

Presynaptic ACh receptor

Question 4

A patient had a road traffic accident (RTA). NCCT head was normal on admission. The patient later died after several days in the ICU due to coma. Brain biopsy revealed multiple punctate hemorrhages. What is the diagnosis?

Accepted Answer

Diffuse axonal injury

Answer

Subdural hemorrhage

Answer

Intraventricular bleeding

Answer

Ischemic injury

Question 5

What defect is seen in Bernard Soulier syndrome?

Accepted Answer

Deficiency of GpIb receptors

Answer

Deficiency of GpIIb/IIIa receptor

Answer

Deficiency of ADP receptors

Answer

Deficiency of von Willebrand factor

Question 6

A skin graft was performed on an immunocompromised patient using tissue from another immunocompromised individual. Weeks later, the patient developed contractures and systemic symptoms. What is the most likely cause?

Accepted Answer

Graft-versus-host disease

Answer

Delayed wound healing

Answer

Rejection due to recipient T8 cells

Answer

Graft failure

Question 7

Which among the following best describes 'Neuropraxia'?

Accepted Answer

Intact axon; Damaged nerve sheath

Answer

None of the above

Answer

Damaged axon and nerve sheath

Answer

Damaged axon; Intact nerve sheath

Question 8

Tau protein inclusions are involved in:

Accepted Answer

Alzheimer’s disease

Answer

Amyotrophic lateral sclerosis

Answer

Huntington's disease

Answer

CNS lymphoma

Question 9

For testing blood clotting/coagulation parameters, blood is collected in which color-coded vacutainer tube?

Accepted Answer

Blue

Answer

Gray

Answer

Red

Answer

Green

Question 10

Which of the following is pro-apoptotic?

Accepted Answer

Bax

Answer

Bcl-2

Answer

Bcl-xL

Answer

Mcl-1

FMGE 2025 — Pathology