NEET-PG 2025 Practice Questions

Q: A patient presents with anemia, positive Romberg sign, and other neurological findings suggestive of vitamin B12 deficiency. Laboratory findings show elevated homocysteine levels. Which amino acid is likely to be deficient in this patient?

Methionine. ***Methionine*** - Vitamin B12 is an essential cofactor for the enzyme **methionine synthase**, which converts **homocysteine** into methionine. - A deficiency in B12 blocks this essential metabolic step, leading to the accumulation of homocysteine and a resultant deficiency of **methionine**. *Cysteine* - **Cysteine** is derived from methionine via **homocysteine** and requires **Vitamin B6** (pyridoxal phosphate) for its synthesis, not Vitamin B12 directly. - While B12 deficiency results in increased homocysteine which is an intermediate, the direct deficiency relates to the product of the B12-dependent step, **methionine**. *Tyrosine* - **Tyrosine** is synthesized from **phenylalanine** by the enzyme phenylalanine hydroxylase, a pathway entirely separate from **Vitamin B12** and homocysteine metabolism. - It is generally considered a non-essential amino acid whose metabolism is disturbed primarily in conditions like **Phenylketonuria (PKU)**. *Glutamate* - **Glutamate** is a crucial excitatory neurotransmitter whose synthesis and metabolism are not directly linked to the **methionine synthase** reaction or **Vitamin B12** deficiency. - Neurological symptoms associated with B12 deficiency (like Romberg sign) are due to impaired **myelin synthesis** caused by reduced SAM (derived from methionine) and methylmalonyl-CoA accumulation.

Q: A woman presents with pruritic rash on the elbows, buttocks with recent diagnosis of gluten sensitive enteropathy. On immunofluorescence IgA deposition is seen as shown in the image. What is the most likely diagnosis?

Dermatitis herpetiformis. ***Dermatitis herpetiformis*** - The combination of severely **pruritic, grouped vesicles (herpetiform)** on extensor surfaces (elbows, buttocks) and underlying **gluten-sensitive enteropathy** is pathognomonic. - The immunofluorescence image demonstrates characteristic **granular IgA deposition** specifically in the **dermal papillae**, which confirms the diagnosis. *Pemphigus vulgaris* - DIF typically shows a **"fishnet" pattern** of **IgG and C3** deposition in the **intercellular spaces** of the epidermis. - Clinically presents with **flaccid intraepidermal bullae** and extensive mucosal erosions, which is distinct from the patient's presentation. *Bullous pemphigoid* - DIF is characterized by **linear deposition of IgG and C3 along the basement membrane zone** (BMZ), not granular IgA in the dermal papillae. - Clinically, it presents with **tense bullae**, often in the elderly, and is not linked to gluten-sensitive enteropathy. *Psoriasis* - This condition is characterized by **erythematous plaques with silvery scales** (Koebner phenomenon is common) and is a papulosquamous disorder, not a bullous disease. - The histopathology involves acanthosis and Munro microabscesses, and it lacks the specific **IgA deposits** seen in the image.

Q: A man has killed a person and is brought for forensic evaluation. What is the first step in the medico-legal management of such a case?

Psychiatric evaluation. ***Psychiatric evaluation*** - The initial step in such a case is to determine the accused individual's **fitness to stand trial** and their **criminal responsibility** (sanity) at the time of committing the offense. - This evaluation provides the necessary medical and legal foundation to decide if the case can proceed to trial, especially concerning the defense of **insanity (M'Naghten rule)**. *Immediate trial of the case* - The trial cannot commence until the accused's **competency** to participate in the legal proceedings has been medically confirmed by a psychiatric report. - Proceeding without a psychiatric evaluation risks violating the accused's rights and may lead to a mistrial if they are later deemed **unfit to plead**. *Declared not guilty* - This is a formal verdict or judgment delivered by the court, signifying the **conclusion** of the trial process, not the initial investigative or management step. - The declaration of 'not guilty' (including 'not guilty by reason of insanity') only occurs after all evidence, including the **psychiatric evidence**, has been presented and evaluated. *Sentenced for murder* - Sentencing is the **final stage** of the judicial process, which takes place only *after* the accused has been conclusively tried and found **guilty** of the crime beyond a reasonable doubt. - This step occurs long after the initial arrest, investigation, psychiatric assessment, and full legal trial are completed.

Q: A child presents with visual disturbances and delayed growth. Imaging reveals a suprasellar mass, and histopathology shows the presence of "wet keratin" (compact, eosinophilic anucleate keratin). What is the most likely diagnosis?

Craniopharyngioma. ***Craniopharyngioma*** - This tumor is classically located in the **suprasellar region** and presents in children with visual field deficits and **endocrine dysfunction** (e.g., delayed growth, short stature) due to hypothalamic or pituitary stalk compression. - The histopathology description of **"wet keratin"** (or keratin nests with peripheral palisading of epithelial cells) is pathognomonic for the adamantinomatous subtype of craniopharyngioma. *Medulloblastoma* - This is primarily a **posterior fossa tumor** originating in the cerebellum, typically causing signs of increased intracranial pressure and **ataxia**, not primarily suprasellar syndromes. - Histologically, it is a small, round blue cell tumor of **primitive neuroectoderm (PNET)** origin; it does not exhibit keratin formation. *Glioma* - While gliomas (e.g., optic pathway gliomas) can involve the suprasellar area, the cellular morphology would consist of **astrocytic** or oligodendroglial cells. - Gliomas lack the epithelial components and definitive **keratin formation** that are characteristic of craniopharyngioma. *Pituitary adenoma* - Pituitary adenomas are typically **intrasellar** and are much more common in adults, causing symptoms associated with hormone excess or deficiency (hypopituitarism) [1]. - Histology shows sheets and cords of uniform **polygonal cells** derived from pituitary endocrinocytes [2]; they do not contain squamous elements or keratin. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, p. 1081. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 417-418.

Q: A patient presents with a mass in the front of the neck, along with odynophagia and dyspnea. Histopathology reveals tumor cells positive for TTF-1, synaptophysin, and chromogranin, and there is evidence of amyloid deposition. What is the most likely diagnosis?

Medullary thyroid carcinoma. ***Medullary thyroid carcinoma*** - The tumor cells are positive for **Synaptophysin** and **Chromogranin**, confirming their **neuroendocrine origin** from the parafollicular C cells [1][2]. - The characteristic finding of **amyloid deposition** is due to the precipitation of stored pro-hormone (primarily **calcitonin**) produced by these C cells, which is highly diagnostic for MTC [2]. *Papillary thyroid carcinoma* - While positive for TTF-1, it is characterized by distinctive nuclear features such as **Orphan Annie eye nuclei** and **nuclear grooves**. - It does **not** exhibit neuroendocrine differentiation (Synaptophysin/Chromogranin negative) or **amyloid deposition**. *Follicular thyroid carcinoma* - This tumor consists of follicular cells and is diagnosed by the demonstration of **capsular** or **vascular invasion**. - It is **negative** for neuroendocrine markers and **lacks** the pathognomonic **calcitonin-derived amyloid**. *Anaplastic thyroid carcinoma* - This is highly malignant and rapidly growing, often presenting with severe compression symptoms, but is histologically characterized by undifferentiated **spindle and giant cells**. - It is typically **negative** for specific neuroendocrine markers and TTF-1 expression is often lost; **amyloid deposits are not a feature**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1102-1103. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 430-431.

Q: A patient with tumor lysis syndrome has elevated uric acid levels. What is the mechanism of action of pegloticase?

Oxidises uric acid. ***Oxidises uric acid*** - Pegloticase is a recombinant pegylated uricase enzyme that directly catalyzes the conversion of highly insoluble **uric acid**. - It oxidizes uric acid into **allantoin**, which is a highly soluble compound easily excreted by the kidneys, effectively lowering serum uric acid levels. *Xanthine oxidase inhibition* - This is the mechanism of action for drugs like **allopurinol** and **febuxostat**, used to prevent the formation of uric acid. - These agents act upstream by inhibiting the enzyme responsible for synthesizing uric acid from xanthine and hypoxanthine. *URAT1 receptor inhibition* - URAT1 inhibitors (**lesinurad**) prevent the reabsorption of native uric acid from the renal tubules back into the bloodstream. - This mechanism is characteristic of **uricosuric agents**, which increase the renal clearance of uric acid. *Excretion of uric acid* - While pegloticase ultimately facilitates excretion (as allantoin), this option is too broad; its primary action is **enzymatic conversion**. - Direct excretion of native uric acid is increased by **uricosuric drugs** (e.g., probenecid), not by pegloticase's oxidative action.

Q: A female patient presents with flashbacks and a history of forgetting about her father's death in a road traffic accident 2 weeks ago. What is the most likely diagnosis?

Acute Stress Disorder (ASD). ***Acute Stress Disorder (ASD)*** - This diagnosis is defined by the presence of severe dissociative, intrusive (**flashbacks**), negative mood, and arousal symptoms occurring between **3 days and 1 month** after exposure to a traumatic event (2 weeks in this case). - The combination of **flashbacks** (intrusion symptom) and forgetting/amnesia (dissociative symptom) is characteristic of the acute reaction to trauma seen in ASD. *Post-Traumatic Stress Disorder (PTSD)* - PTSD requires similar symptoms (intrusion, avoidance, negative alterations in cognition/mood) to persist for **more than 1 month** following the traumatic event. - Since the event occurred only 2 weeks ago, the required duration criterion for a PTSD diagnosis has not been fulfilled yet. *Dissociative Amnesia* - While the patient exhibits amnesia, this diagnosis is generally reserved for extensive memory loss concerning important **autobiographical information**, not better explained by another mental disorder. - The presence of accompanying **flashbacks** and the acute time frame following the trauma better support the diagnosis of ASD. *Adjustment Disorder* - Adjustment disorder involves emotional or behavioral symptoms developed within 3 months of an identifiable stressor, but the symptoms are not severe enough to meet criteria for ASD or PTSD. - The presence of severe clinical features like **flashbacks** and **dissociative amnesia** excludes an Adjustment Disorder diagnosis, as it meets the criteria for the more specific and severe ASD.

Q: A person was found in a bizarre location, appearing confused. The caretaker reports he had no memory of how he got there, and the patient is unaware of his travel to the location. What is the most likely diagnosis?

Dissociative fugue. ***Dissociative fugue*** - This diagnosis is defined by **sudden, unexpected travel** away from home or the known environment, coupled with the inability to recall one's past or identity details (generalized **amnesia** for the journey). - The patient being found in a **bizarre location** and having no memory of the travel perfectly encapsulates the clinical definition of a dissociative fugue (a specifier of Dissociative Amnesia in DSM-5). *Dissociative identity disorder* - The hallmark feature is the presence of **two or more distinct personality states** or alters, which recurrently take control of the person's behavior. - While amnesia is present, it involves gaps in the recall of everyday events, not just isolated memory loss related specifically to an unexpected journey. *Dissociative amnesia* - This involves the inability to recall important personal information, usually of a **stressful or traumatic nature**, that is too extensive to be explained by ordinary forgetting. - Simple dissociative amnesia lacks the specific component of **purposeful, unplanned travel** away from home that characterizes a fugue state. *Psychotic episode* - Psychotic disorders are characterized by **positive symptoms** like **delusions** (fixed false beliefs) and **hallucinations** (perceptual disturbances). - The patient's confusion stems from a lack of memory regarding the journey (**dissociation**), not from a primary break with reality or thought disorder.

Q: A man reports that he is receiving orders from God to follow white birds in a specific direction. What is the most appropriate description of this symptom?

Passivity phenomenon. ***Passivity phenomenon*** - This symptom describes **delusions of control** (also called **made acts** or **passivity of volition**), which is a type of **passivity phenomenon**. - The patient believes that an **external force (God) is giving orders** and directing their actions (following white birds in a specific direction). - This represents the experience of **being controlled or influenced by an external agency**, which is a **First Rank Symptom** of schizophrenia according to Kurt Schneider. - The key feature is the belief in **external control over one's will or actions**, not merely attaching meaning to a perception. *Delusional perception* - This requires a **two-step process**: (1) a normal perception occurs, then (2) this perception is suddenly given **delusional significance** (e.g., "I saw the traffic light turn red and instantly knew I was the Messiah"). - The scenario described does **not** show the birds triggering a new delusional belief; rather, the patient already has an **established delusion of receiving divine commands**. - The birds are the **medium** through which control is exerted, not a perception given new meaning. *Visual hallucination* - A **hallucination** is a perception occurring in the **absence of an external stimulus**. - Since the white birds are actually present and the patient is seeing real birds, this is **not** a hallucination. - The pathology lies in the **delusional belief about being commanded**, not in perceiving something that isn't there. *Thought insertion* - This is a First Rank Symptom where the patient believes **thoughts are being inserted into their mind** by an external force. - The current scenario involves **receiving orders to perform actions** (passivity of volition), not the experience of alien thoughts being placed in one's mind. - While both involve external agency, thought insertion specifically concerns **thoughts**, whereas this case concerns **volitional control**.

Question 1

A patient presents with anemia, positive Romberg sign, and other neurological findings suggestive of vitamin B12 deficiency. Laboratory findings show elevated homocysteine levels. Which amino acid is likely to be deficient in this patient?

Accepted Answer

Methionine

Answer

Tyrosine

Answer

Cysteine

Answer

Glutamate

Question 2

A woman presents with pruritic rash on the elbows, buttocks with recent diagnosis of gluten sensitive enteropathy. On immunofluorescence IgA deposition is seen as shown in the image. What is the most likely diagnosis?

Accepted Answer

Dermatitis herpetiformis

Answer

Psoriasis

Answer

Bullous pemphigoid

Answer

Pemphigus vulgaris

Question 3

A man has killed a person and is brought for forensic evaluation. What is the first step in the medico-legal management of such a case?

Accepted Answer

Psychiatric evaluation

Answer

Sentenced for murder

Answer

Declared not guilty

Answer

Immediate trial of the case

Question 4

A child presents with visual disturbances and delayed growth. Imaging reveals a suprasellar mass, and histopathology shows the presence of "wet keratin" (compact, eosinophilic anucleate keratin). What is the most likely diagnosis?

Accepted Answer

Craniopharyngioma

Answer

Medulloblastoma

Answer

Glioma

Answer

Pituitary adenoma

Question 5

A patient presents with a mass in the front of the neck, along with odynophagia and dyspnea. Histopathology reveals tumor cells positive for TTF-1, synaptophysin, and chromogranin, and there is evidence of amyloid deposition. What is the most likely diagnosis?

Accepted Answer

Medullary thyroid carcinoma

Answer

Follicular thyroid carcinoma

Answer

Papillary thyroid carcinoma

Answer

Anaplastic thyroid carcinoma

Question 6

A middle-aged woman presents with dry eyes and dry mouth. Laboratory tests reveal positive anti-Ro (SSA) and anti-La (SSB) antibodies. What is the most likely underlying pathological mechanism?

Accepted Answer

Lymphocytic infiltration and destruction of salivary and lacrimal glands

Answer

IgE-mediated hypersensitivity reaction

Answer

Destruction of exocrine glands by neutrophils

Answer

Deposition of amyloid in salivary glands

Question 7

A patient with tumor lysis syndrome has elevated uric acid levels. What is the mechanism of action of pegloticase?

Accepted Answer

Oxidises uric acid

Answer

Urat-1 receptor inhibition

Answer

Xanthine oxidase inhibition

Answer

Excretion of uric acid

Question 8

A female patient presents with flashbacks and a history of forgetting about her father's death in a road traffic accident 2 weeks ago. What is the most likely diagnosis?

Accepted Answer

Acute Stress Disorder (ASD)

Answer

Dissociative Amnesia

Answer

Post-Traumatic Stress Disorder (PTSD)

Answer

Adjustment Disorder

Question 9

A person was found in a bizarre location, appearing confused. The caretaker reports he had no memory of how he got there, and the patient is unaware of his travel to the location. What is the most likely diagnosis?

Accepted Answer

Dissociative fugue

Answer

Dissociative amnesia

Answer

Dissociative identity disorder

Answer

Psychotic episode

Question 10

A man reports that he is receiving orders from God to follow white birds in a specific direction. What is the most appropriate description of this symptom?

Accepted Answer

Passivity phenomenon

Answer

Delusional perception

Answer

Visual hallucination

Answer

Thought insertion

NEET-PG 2025

Biochemistry

Dermatology

Forensic Medicine

Pathology

Pharmacology

Psychiatry