General Pathology Practice Questions

Q: Intermediate filaments (IFs) help link adjacent sarcomeres together in skeletal muscle. Which of the following proteins is an intermediate filament protein used diagnostically in pathologic cases to indicate muscle origin?

Desmin. **Explanation:** Intermediate filaments (IFs) are essential components of the cytoskeleton that provide mechanical strength to cells. In muscle tissue (skeletal, cardiac, and smooth), the primary intermediate filament protein is **Desmin**. 1. **Why Desmin is Correct:** Desmin forms a lattice that surrounds the Z-discs of sarcomeres, linking them to each other and to the plasma membrane (sarcolemma). In diagnostic pathology, Desmin is a highly specific **Immunohistochemical (IHC) marker**. Its presence is used to identify tumors of muscle origin, such as **Rhabdomyosarcoma** (skeletal muscle) or **Leiomyosarcoma** (smooth muscle). 2. **Analysis of Incorrect Options:** * **Actin (A):** While actin is a major contractile protein in muscle, it is classified as a **microfilament** (6-7 nm), not an intermediate filament (10 nm). * **Actinin (C):** Alpha-actinin is an anchoring protein found in the Z-discs that binds actin filaments; it is not an intermediate filament. * **Clathrin (D):** This is a protein involved in the formation of coated vesicles for **receptor-mediated endocytosis**, unrelated to the muscle cytoskeleton. **High-Yield Clinical Pearls for NEET-PG:** * **Vimentin:** The IF marker for mesenchymal cells (connective tissue, sarcomas). * **Cytokeratin:** The IF marker for epithelial cells (carcinomas). * **GFAP:** The IF marker for glial cells (astrocytomas). * **Neurofilaments:** The IF marker for neurons (neuroblastoma, pheochromocytoma). * **Mallory-Denk Bodies:** These are inclusions found in alcoholic liver disease composed of pre-keratin intermediate filaments.

Q: A 58-year-old man suffered a road traffic accident and came to the hospital. He had multiple fractures in his lower limbs, ribs, and lung contusion. Ultimately, he succumbed to his injuries. At autopsy, a biopsy from the lung showed certain microscopic findings. What is the likely cause of his death?

Fat embolism. ***Fat embolism*** - Following **multiple long bone fractures**, fat globules from bone marrow enter circulation and lodge in **pulmonary capillaries**, causing respiratory failure and death. - Microscopic lung biopsy would show **fat globules** in capillaries, visible with **Oil Red O staining** or as **clear spaces** on H&E sections. *Emphysema* - A chronic condition characterized by **destruction of alveolar walls** and **air space enlargement**, not an acute cause of death following trauma. - Would not be caused by recent **multiple fractures** and typically develops over years due to smoking or **alpha-1 antitrypsin deficiency**. *Pulmonary embolism* - Caused by **blood clots** (usually from deep vein thrombosis) blocking pulmonary arteries, not fat globules from bone marrow. - Microscopic findings would show **fibrin clots** and **red blood cells** in vessels, not the **fat globules** seen in this trauma case. *Congestive heart failure* - Results from **impaired cardiac function** leading to fluid accumulation and would show **pulmonary edema** microscopically. - Unlikely to be the primary cause of death in acute trauma with **multiple fractures**, and wouldn't explain the specific microscopic lung findings.

Q: All of the following are X-linked except?

Von Willebrandt's disease. **Explanation:** The correct answer is **Von Willebrand Disease (vWD)** because it is primarily an **autosomal dominant** disorder (Type 1 and 2) or, less commonly, autosomal recessive (Type 3). It is caused by mutations in the *VWF* gene located on **chromosome 12**, not the X chromosome. **Analysis of Options:** * **A. G-6PD Deficiency:** This is a classic **X-linked recessive** enzymopathy. It leads to neonatal jaundice or acute hemolytic anemia triggered by oxidative stress (e.g., fava beans, primaquine). * **B. Hemophilia A:** This is an **X-linked recessive** bleeding disorder caused by a deficiency of Factor VIII. It predominantly affects males, while females are typically asymptomatic carriers. * **D. Fragile X Syndrome:** This is an **X-linked dominant** condition (with variable expressivity) caused by CGG trinucleotide repeat expansion in the *FMR1* gene. It is the most common cause of inherited intellectual disability. **High-Yield Clinical Pearls for NEET-PG:** * **vWD vs. Hemophilia:** vWD is the **most common inherited bleeding disorder** overall. Unlike Hemophilia (which affects deep tissues/joints), vWD typically presents with mucosal bleeding (epistaxis, menorrhagia) and a prolonged bleeding time. * **Mnemonic for X-linked Recessive Disorders:** "**G**o **H**ome **F**or **D**inner **M**y **L**ittle **B**oy" (**G**6PD, **H**emophilia A/B, **F**abry’s, **D**uchenne Muscular Dystrophy, **M**enke’s, **L**esch-Nyhan, **B**ruton’s Agammaglobulinemia). * **Exception:** While most Hemophilias are X-linked, **Hemophilia C** (Factor XI deficiency) is autosomal recessive.

Question 1

Which finding on electron microscopy indicates irreversible cell injury?

Accepted Answer

Flocculent densities in the mitochondria

Answer

Dilatation of endoplasmic reticulum

Answer

Dissociation of ribosomes from rough endoplasmic reticulum

Answer

Myelin figures

Question 2

A 32-year-old woman with poorly controlled diabetes mellitus delivers a healthy boy at 38 weeks of gestation. As a result of maternal hyperglycemia during pregnancy, what morphologic response would be expected in the pancreatic islets of the neonate?

Accepted Answer

Hyperplasia

Answer

Atrophy

Answer

Dysplasia

Answer

Metaplasia

Question 3

Intermediate filaments (IFs) help link adjacent sarcomeres together in skeletal muscle. Which of the following proteins is an intermediate filament protein used diagnostically in pathologic cases to indicate muscle origin?

Accepted Answer

Desmin

Answer

Actin

Answer

Actinin

Answer

Clathrin

Question 4

A 58-year-old man suffered a road traffic accident and came to the hospital. He had multiple fractures in his lower limbs, ribs, and lung contusion. Ultimately, he succumbed to his injuries. At autopsy, a biopsy from the lung showed certain microscopic findings. What is the likely cause of his death?

Accepted Answer

Fat embolism

Answer

Emphysema

Answer

Pulmonary embolism

Answer

Congestive heart failure

Question 5

Which of the following is NOT a feature or common association of psammoma bodies?

Accepted Answer

Seen in teratoma

Answer

Seen in meningioma

Answer

Concentric whorled appearance

Answer

Seen in papillary thyroid carcinoma

Question 6

All of the following are X-linked except?

Accepted Answer

Von Willebrandt's disease

Answer

G-6 PD deficiency

Answer

Hemophilia - A

Answer

Fragile X syndrome

Question 7

A 22-year-old woman delivers an apparently healthy female infant after an uncomplicated pregnancy. By 4 years of age, the girl has progressive, severe neurologic deterioration. Physical examination shows marked hepatosplenomegaly. A bone marrow biopsy specimen shows numerous foamy vacuolated macrophages. Analysis of which of the following factors is most likely to aid in the diagnosis of this condition?

Accepted Answer

Level of sphingomyelinase in splenic macrophages

Answer

Level of a1-antitrypsin in the serum

Answer

Level of glucose-6-phosphatase in hepatocytes

Answer

Number of LDL receptors on hepatocytes

Question 8

What is the first manifestation in cell injury?

Accepted Answer

Cell swelling

Answer

Pyknosis

Answer

Nuclear fragmentation

Answer

Nuclear lysis

Question 9

What is the inheritance pattern of the ABO blood group system and the HLA system?

Accepted Answer

Codominant

Answer

Pseudodominance

Answer

Autosomal dominant

Answer

Autosomal recessive

Question 10

Which procedure is performed when amyloidosis is clinically suspected?

Accepted Answer

Congo red staining of abdominal fat

Answer

Renal biopsy

Answer

Urine electrophoresis

Answer

Serum immunoelectrophoresis

General Pathology — MCQs

General Pathology — MCQs

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