NEET-PG 2024 Practice Questions

Q: Which of the following antibodies is associated with Celiac disease?

Anti-TTG (Tissue Transglutaminase). ***Anti-TTG (Tissue Transglutaminase)*** - **Anti-TTG antibodies** (especially **IgA**) are the primary serological markers for celiac disease, demonstrating high sensitivity and specificity. - These antibodies target **tissue transglutaminase**, an enzyme involved in gluten deamidation, which triggers the autoimmune response in genetically predisposed individuals. - **Anti-TTG IgA** is the **preferred initial screening test** due to its superior diagnostic accuracy and cost-effectiveness. *ANCA (Anti-Neutrophil Cytoplasmic Antibodies)* - **ANCA** are associated with **vasculitis**, such as **Granulomatosis with Polyangiitis (Wegener's)** and **Microscopic Polyangiitis**. - They are not a diagnostic marker for celiac disease, which is an autoimmune enteropathy. *ASCA (Anti-Saccharomyces cerevisiae Antibodies)* - **ASCA** are commonly found in patients with **Crohn's disease**, particularly in those with ileal involvement. - While both celiac disease and Crohn's are gastrointestinal conditions, ASCA is not a marker for celiac. *Anti-gliadin* - **Anti-gliadin antibodies (AGA)** were historically used in celiac disease diagnosis but have **lower sensitivity and specificity** compared to anti-TTG and anti-endomysial antibodies. - Modern guidelines recommend using **anti-TTG IgA** as the primary screening tool due to its superior diagnostic accuracy. *Anti-EMA (Endomysial Antibodies)* - **Anti-EMA IgA** is highly specific for celiac disease (>95% specificity) and is often used as a **confirmatory test**. - However, **anti-TTG is preferred for initial screening** because anti-EMA testing is more expensive, operator-dependent (uses immunofluorescence), and less widely available. - Anti-EMA targets the same antigen as anti-TTG (tissue transglutaminase).

Q: A patient is a known case of thalassemia. Which of the following viruses would be responsible for attacking progenitor cells and causing aplastic anemia?

Parvovirus B19. ***Parvovirus B19*** - **Parvovirus B19** specifically targets and replicates in **erythroid progenitor cells** in the bone marrow, leading to a temporary halt in red blood cell production [1]. - In patients with chronic hemolytic anemias like **thalassemia**, who already have increased erythropoietic demands, this can precipitate an **aplastic crisis** or pure red cell aplasia [1], [2]. *CMV (Cytomegalovirus)* - While CMV can affect the bone marrow and lead to myelosuppression, it does not typically cause a direct **aplastic crisis** by targeting erythroid progenitors in the same way as Parvovirus B19. - CMV often presents with a wider range of symptoms including fever, hepatitis, and mononucleosis-like syndrome, and bone marrow suppression is usually multi-lineage or less severe. *EBV (Epstein-Barr Virus)* - EBV is known to cause infectious mononucleosis and can also be associated with some bone marrow disorders, but it does not primarily target **erythroid progenitor cells** to cause an aplastic crisis. - Its main target cells are **B lymphocytes**, and any bone marrow suppression is often secondary to immune dysregulation rather than direct lytic infection of stem cells. *Hepatitis C virus (HCV)* - HCV infection can lead to various hematologic manifestations, including aplastic anemia, but these are typically **immune-mediated** or associated with chronic liver disease and its complications. - HCV does not directly infect and destroy **hematopoietic progenitor cells** in the bone marrow as a primary mechanism of aplastic anemia.

Q: TTF-1 (Thyroid Transcription Factor-1) immunohistochemical marker is most commonly seen in which of the following?

Lung adenocarcinoma. ***Lung adenocarcinoma*** - **TTF-1 (Thyroid Transcription Factor-1)** is a nuclear transcription factor that is highly expressed in adenocarcinomas of the lung. Positivity for TTF-1 is a key marker used in the diagnosis of primary lung adenocarcinoma, distinguishing it from other lung cancers and metastatic tumors. - While TTF-1 can also be positive in thyroid follicular and papillary carcinomas, its strong association with **lung adenocarcinoma** makes it a crucial diagnostic marker in this context, especially when differentiating between primary lung tumors and metastases or other lung cancer types. *Squamous Cell Carcinoma (SCC)* - **Squamous cell carcinoma of the lung** is generally **negative for TTF-1**. It typically expresses markers like p40 and CK5/6. - TTF-1 has very low sensitivity and specificity for squamous cell carcinoma, making it a poor choice for identifying this type of lung cancer. *Large cell lung cancer* - **Large cell lung carcinoma** is a diagnosis of exclusion and is typically **negative for TTF-1**, as well as other specific markers for adenocarcinoma or squamous cell carcinoma. - This type of cancer is characterized by large, anaplastic cells that lack features of other specific lung cancer types when viewed under a microscope. *Papillary thyroid carcinoma* - While **papillary thyroid carcinoma** is also **TTF-1 positive**, the question asks for the most common context in which TTF-1 is seen, and TTF-1 is a highly valuable marker for confirming a lung primary in the setting of lung masses. - TTF-1's utility in lung cancer diagnostics is particularly significant for differentiating primary lung adenocarcinomas from metastatic tumors and other lung cancer subtypes.

Q: The skin biopsy shown below is most consistent with which of the following conditions? ![img-28.jpeg](img-28.jpeg)

Lichen planus. ***Lichen planus*** - The image shows **basal cell degeneration** (liquefaction degeneration), a **sawtooth rete ridge pattern**, and a band-like inflammatory infiltrate primarily composed of lymphocytes at the dermo-epidermal junction, which are classic histological features of **lichen planus**. - **Civatte bodies** (apoptotic keratinocytes forming colloid bodies) are typically present, resulting from keratinocyte damage at the basal layer. - These features make lichen planus the most consistent diagnosis. *Lichen nitidus* - Characterized by **"ball and claw" lesions**, which are small, localized epidermal invaginations enclosing a central infiltrate of lymphocytes and histiocytes. - The granulomatous infiltrate is more focal and circumscribed compared to the band-like pattern of lichen planus. - While both are interface dermatitides, the architectural pattern differs significantly. *Morphea* - This is a localized form of **scleroderma**, characterized by increased **collagen deposition**, thickening of the dermis, and loss of adnexal structures like hair follicles and sweat glands. - The inflammatory infiltrate is typically perivascular and interstitial, not band-like at the dermo-epidermal junction. - The image does not show features of dermal fibrosis or homogenization of collagen bundles expected in morphea. *Lupus erythematosus* - Also shows **interface dermatitis** with basal vacuolar changes and lymphocytic infiltrate. - However, lupus typically shows a **perivascular and periappendageal pattern** of infiltrate rather than the dense band-like pattern of lichen planus. - Additional features in lupus include dermal mucin deposition, thickened basement membrane (PAS-positive), and follicular plugging. - The dense, continuous band-like infiltrate and sawtooth rete ridges favor lichen planus over lupus.

Q: The histopathology image shown is characteristic of which of the following diseases? ![img-30.jpeg](img-30.jpeg)

Gaucher's disease. ***Gaucher's disease*** - The image shows **Gaucher cells** - characteristic lipid-laden macrophages with a distinctive **"crumpled tissue paper" or "wrinkled silk" cytoplasmic appearance** and eccentric nuclei [1] - These cells are pathognomonic for **Gaucher's disease**, an **autosomal recessive lysosomal storage disorder** caused by **glucocerebrosidase deficiency** [1] - Accumulation of **glucocerebroside** in macrophages creates the characteristic morphology seen in bone marrow, spleen, and liver [1] - Caused by mutations in the *GBA* gene on chromosome 1 [1] *Tay-Sachs disease* - Autosomal recessive disorder caused by **hexosaminidase A deficiency** leading to **GM2 ganglioside accumulation** [2] - Characteristic findings include **cherry-red spot on macula** and neuronal ballooning, not the macrophage changes seen in this image [2] - Does not produce Gaucher cells *Sandhoff's disease* - Caused by deficiency of both **hexosaminidase A and B** due to *HEXB* gene mutations - Similar to Tay-Sachs with GM2 ganglioside accumulation affecting neurons - Does not produce the characteristic macrophage morphology shown in the image *Fabry's disease* - **X-linked recessive** disorder caused by **alpha-galactosidase A deficiency** - Accumulation of **globotriaosylceramide** in vascular endothelial cells - Histology may show lipid deposits in vessels and kidney, not the distinctive Gaucher cells seen here **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 162-163. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, p. 161.

Q: A male patient is not responding to oxygen therapy and has been diagnosed with ARDS (Acute Respiratory Distress Syndrome). What is the role of IL-8 in ARDS?

Recruitment of neutrophils. Recruitment of neutrophils - **Interleukin-8 (IL-8)**, also known as **CXCL8**, is a powerful **chemotactic cytokine** that primarily attracts and activates neutrophils [3]. - In **ARDS**, this recruitment leads to an influx of neutrophils into the pulmonary interstitium and alveolar spaces, contributing to inflammation and lung injury [1]. *Endothelial cell activation* - While other **cytokines** and inflammatory mediators can activate **endothelial cells** in ARDS [2], IL-8's primary role is not direct endothelial activation but rather **neutrophil chemotaxis** [3]. - **Endothelial cell activation** leads to increased vascular permeability and leukocyte adherence, which is often a consequence of overall inflammation, not solely IL-8 [4]. *Macrophage activation* - **Macrophages** are activated by various stimuli and other **cytokines**, such as **TNF-alpha** and **IFN-gamma**, as part of the inflammatory response. - While macrophages produce IL-8, its main function is not to activate macrophages themselves but to attract **neutrophils**. *Promote surfactant production* - **Surfactant production** is primarily regulated by **Type II pneumocytes** and is often impaired in ARDS due to damage to these cells [1]. - IL-8 is a **pro-inflammatory cytokine** and plays no direct role in promoting surfactant synthesis; in fact, its inflammatory effects can indirectly worsen surfactant dysfunction. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 681. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 679. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 87-89. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Migration in the tissues toward a chemotactic stimulus, pp. 86-87.

Q: A child presents with itchy lesions and diarrhea and has been advised to follow a gluten-free diet. What is the most likely etiology of this condition?

Celiac disease. ***Celiac disease*** - **Celiac disease** is an autoimmune condition triggered by **gluten ingestion**, leading to small intestine damage and nutrient malabsorption. - The combination of **itchy lesions** (dermatitis herpetiformis, a skin manifestation of celiac disease), **diarrhea**, and improvement on a **gluten-free diet** are highly characteristic. - Since the question asks for the **underlying etiology**, celiac disease is the correct answer as it causes both the skin and GI manifestations. *Whipple's disease* - This is a rare systemic infection caused by the bacterium **Tropheryma whipplei**, presenting with **arthralgia, fever, malabsorption, and lymphadenopathy**. - While it can cause diarrhea and malabsorption, it is not associated with itchy skin lesions and does not respond to a gluten-free diet. *Crohn's disease* - **Crohn's disease** is a type of inflammatory bowel disease affecting any part of the GI tract, causing **abdominal pain, diarrhea, and weight loss**. - It is not associated with dermatitis herpetiformis and does not improve with a gluten-free diet (though some patients may have gluten sensitivity). *Dermatitis herpetiformis* - **Dermatitis herpetiformis** is the **cutaneous manifestation of celiac disease**, presenting as intensely itchy, vesicular lesions. - While DH explains the itchy lesions in this case, it is a **symptom/manifestation**, not the underlying **etiology**—the root cause is celiac disease itself, which produces both the intestinal damage (diarrhea) and the skin manifestations (DH).

Question 1

Which of the following antibodies is associated with Celiac disease?

Accepted Answer

Anti-TTG (Tissue Transglutaminase)

Answer

ANCA (Anti-Neutrophil Cytoplasmic Antibodies)

Answer

ASCA (Anti-Saccharomyces cerevisiae Antibodies)

Answer

Anti-gliadin

Answer

Anti-EMA (Endomysial Antibodies)

Question 2

A patient is a known case of thalassemia. Which of the following viruses would be responsible for attacking progenitor cells and causing aplastic anemia?

Accepted Answer

Parvovirus B19

Answer

CMV (Cytomegalovirus)

Answer

EBV (Epstein-Barr Virus)

Answer

Hepatitis C virus (HCV)

Question 3

A patient has a cerebellar mass, renal tumor, and a family history of similar conditions. Which of the following mutations is most likely present in the family?

Accepted Answer

VHL

Answer

Neurofibromatosis (NF1)

Answer

Tuberous Sclerosis Complex (TSC)

Answer

Li-Fraumeni syndrome

Question 4

TTF-1 (Thyroid Transcription Factor-1) immunohistochemical marker is most commonly seen in which of the following?

Accepted Answer

Lung adenocarcinoma

Answer

Squamous Cell Carcinoma (SCC)

Answer

Large cell lung cancer

Answer

Papillary thyroid carcinoma

Question 5

A 30-year-old football player presented to the emergency department with sudden cardiac arrest/collapse. Based on the histological image provided, what is the most likely cause of his death?

Accepted Answer

Hypertrophic Obstructive Cardiomyopathy (HOCM)

Answer

Dilated Cardiomyopathy (DCM)

Answer

Restrictive Cardiomyopathy (RCM)

Answer

Arrhythmogenic cardiomyopathy

Question 6

The skin biopsy shown below is most consistent with which of the following conditions?
![img-28.jpeg](img-28.jpeg)

Accepted Answer

Lichen planus

Answer

Lichen nitidus

Answer

Morphea

Answer

Lupus erythematosus

Question 7

A 23-year-old female with a height of 4 feet has a karyotype as shown in the image below. Which among the following indicates the correct etiology?

Accepted Answer

Turner syndrome

Answer

Klinefelter's syndrome

Answer

Down syndrome

Answer

Edward's syndrome

Question 8

The histopathology image shown is characteristic of which of the following diseases?
![img-30.jpeg](img-30.jpeg)

Accepted Answer

Gaucher's disease

Answer

Tay-Sachs disease

Answer

Sandhoff's disease

Answer

Fabry's disease

Question 9

A male patient is not responding to oxygen therapy and has been diagnosed with ARDS (Acute Respiratory Distress Syndrome). What is the role of IL-8 in ARDS?

Accepted Answer

Recruitment of neutrophils

Answer

Endothelial cell activation

Answer

Macrophage activation

Answer

Promote surfactant production

Question 10

A child presents with itchy lesions and diarrhea and has been advised to follow a gluten-free diet. What is the most likely etiology of this condition?

Accepted Answer

Celiac disease

Answer

Whipple's disease

Answer

Crohn's disease

Answer

Dermatitis herpetiformis

NEET-PG 2024

Internal Medicine

Microbiology

Pathology

Pediatrics