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 patient presents with irregular swelling over the foot, multiple discharging sinuses, and black granules. A KOH mount is performed on the discharge. What is the most likely observation?

Slender dematiaceous fungi. ***Slender dematiaceous fungi*** - The clinical triad of irregular swelling, multiple discharging sinuses, and the presence of **black granules** strongly suggests **black-grained eumycetoma** (e.g., caused by *Madurella mycetomatis*). - KOH mount of the black granule reveals densely packed, brown-to-black pigmented (**dematiaceous**) septate hyphal elements and chlamydospores, consistent with slender dematiaceous fungi. *Arthrospores* - Arthrospores are typically seen in superficial infections like **dermatophytosis** (e.g., Tinea capitis, *Trichophyton*) or are characteristic of the parasitic phase of *Coccidioides immitis*. - They are not the primary microscopic finding within the tissue granule of mycetoma. *Yeast* - Yeast forms are characteristic of systemic infections like **Candidiasis**, Cryptococcosis, or Histoplasmosis, or are seen as sclerotic (Medlar) bodies in **Chromoblastomycosis**. - Mycetoma granules are formed by highly organized masses of filamentous hyphae, not unicellular yeast. *Septate hyphae 4-5* - This describes the general morphology and width of hyphae seen in common molds like **Aspergillus** or *Fusarium*. - This description is incomplete for black-grained mycetoma as it omits the distinctive feature of the fungus being pigmented (**dematiaceous**), which is critical for identifying the organism within the black granule.

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 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**.

Q: A 25-year-old male was injured during an earthquake. A social worker reports that he was later found in another town, and the man has no memory of how he got there or of his personal identity. What is the most likely diagnosis?

Dissociative amnesia with dissociative fugue. ***Dissociative amnesia with dissociative fugue*** - In **DSM-5**, dissociative fugue is no longer a separate disorder but a **specifier** of dissociative amnesia. - It is characterized by **sudden, unexpected travel** away from home or customary workplace along with an **inability to recall** some or all of one's past. - This condition involves **amnesia regarding one's identity** (personal identity/autobiographical memory) and is frequently precipitated by severe psychological trauma or stress (the earthquake). - The combination of **purposeful travel** to another location and **loss of personal identity** is pathognomonic for this specifier. *Dissociative identity disorder* - This disorder involves the presence of two or more distinct **personality states** (alters) that recurrently take control of behavior. - The primary feature is **fragmentation of identity**, not the transient, single episode of extensive travel and sudden amnesia described here. *Acute stress disorder* - This diagnosis requires symptoms (e.g., intrusion, negative mood, avoidance, dissociation) to occur within **3 days to 1 month** after exposure to trauma. - While trauma is present, the specific symptom combination of **purposeful wandering** and **loss of personal identity** is the critical differentiating factor for dissociative fugue. *PTSD* - This diagnosis requires symptoms (intrusion, avoidance, hyperarousal) to persist for **more than one month** following the traumatic event. - The key features presented are **flight** (wandering to another town) and **extensive identity amnesia**, which are characteristic of the dissociative fugue specifier, not core PTSD symptoms.

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 patient presents with irregular swelling over the foot, multiple discharging sinuses, and black granules. A KOH mount is performed on the discharge. What is the most likely observation?

Accepted Answer

Slender dematiaceous fungi

Answer

Yeast

Answer

Septate hyphae 4-5

Answer

Arthrospores

Question 5

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 6

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 7

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 8

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 9

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

Question 10

A 25-year-old male was injured during an earthquake. A social worker reports that he was later found in another town, and the man has no memory of how he got there or of his personal identity. What is the most likely diagnosis?

Accepted Answer

Dissociative amnesia with dissociative fugue

Answer

Dissociative identity disorder

Answer

Acute stress disorder

Answer

PTSD

NEET-PG 2025

Biochemistry

Dermatology

Forensic Medicine

Microbiology

Pathology

Pharmacology

Psychiatry