Biochemistry
1 questionsA 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?
NEET-PG 2025 - Biochemistry NEET-PG Practice Questions and MCQs
Question 31: 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?
- A. Methionine (Correct Answer)
- B. Tyrosine
- C. Cysteine
- D. Glutamate
Explanation: ***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.
Dermatology
1 questionsA 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?
NEET-PG 2025 - Dermatology NEET-PG Practice Questions and MCQs
Question 31: 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?
- A. Psoriasis
- B. Dermatitis herpetiformis (Correct Answer)
- C. Bullous pemphigoid
- D. Pemphigus vulgaris
Explanation: ***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.
Forensic Medicine
1 questionsA 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?
NEET-PG 2025 - Forensic Medicine NEET-PG Practice Questions and MCQs
Question 31: 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?
- A. Sentenced for murder
- B. Psychiatric evaluation (Correct Answer)
- C. Declared not guilty
- D. Immediate trial of the case
Explanation: ***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.
Microbiology
1 questionsA 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?
NEET-PG 2025 - Microbiology NEET-PG Practice Questions and MCQs
Question 31: 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?
- A. Slender dematiaceous fungi (Correct Answer)
- B. Yeast
- C. Septate hyphae 4-5
- D. Arthrospores
Explanation: ***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.
Pathology
3 questionsA 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?
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?
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?
NEET-PG 2025 - Pathology NEET-PG Practice Questions and MCQs
Question 31: 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?
- A. Medulloblastoma
- B. Glioma
- C. Craniopharyngioma (Correct Answer)
- D. Pituitary adenoma
Explanation: ***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.
Question 32: 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?
- A. Follicular thyroid carcinoma
- B. Medullary thyroid carcinoma (Correct Answer)
- C. Papillary thyroid carcinoma
- D. Anaplastic thyroid carcinoma
Explanation: ***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.
Question 33: 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?
- A. IgE-mediated hypersensitivity reaction
- B. Lymphocytic infiltration and destruction of salivary and lacrimal glands (Correct Answer)
- C. Destruction of exocrine glands by neutrophils
- D. Deposition of amyloid in salivary glands
Explanation: ***Lymphocytic infiltration and destruction of salivary and lacrimal glands*** - Sjögren's syndrome (suggested by dry eyes, dry mouth, and **anti-Ro/SSA** & **anti-La/SSB** positivity) is pathologically defined by intense focal **lymphocytic infiltration** (primarily CD4+ T cells) within the affected exocrine glands [1]. - This chronic autoimmune damage, also known as focal glandular adenitis, leads to atrophy and functional abolition of the **salivary** and **lacrimal glands**, causing sicca symptoms [2]. *Destruction of exocrine glands by neutrophils* - **Neutrophils** are primarily involved in acute inflammation or bacterial infections; they are not the hallmark destructive cell type in this **chronic autoimmune disease**. - The characteristic lesion in Sjögren's syndrome involves extensive infiltration by **lymphocytes**, not neutrophils [1]. *IgE-mediated hypersensitivity reaction* - This type of reaction (Type I) involves mast cell degranulation and is responsible for **allergic responses** and anaphylaxis, which is clinically and pathologically distinct from Sjögren's syndrome. - Sjögren's syndrome involves **Type IV (cell-mediated)** and **Type III (immune complex)** pathology, evidenced by T-cell infiltration and autoantibodies [1]. *Deposition of amyloid in salivary glands* - **Amyloidosis** causing salivary gland enlargement is a rare cause of xerostomia and is characterized by misfolded protein deposition, not by profound **lymphocytic infiltration**. - The presence of specific autoantibodies (**anti-Ro/SSA, anti-La/SSB**) confirms a diagnosis of Sjögren's syndrome, making amyloidosis highly unlikely [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 234-236. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 749-750.
Pharmacology
1 questionsA patient with tumor lysis syndrome has elevated uric acid levels. What is the mechanism of action of pegloticase?
NEET-PG 2025 - Pharmacology NEET-PG Practice Questions and MCQs
Question 31: A patient with tumor lysis syndrome has elevated uric acid levels. What is the mechanism of action of pegloticase?
- A. Urat-1 receptor inhibition
- B. Oxidises uric acid (Correct Answer)
- C. Xanthine oxidase inhibition
- D. Excretion of uric acid
Explanation: ***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.
Psychiatry
2 questionsA 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?
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?
NEET-PG 2025 - Psychiatry NEET-PG Practice Questions and MCQs
Question 31: 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?
- A. Delusional perception
- B. Visual hallucination
- C. Passivity phenomenon (Correct Answer)
- D. Thought insertion
Explanation: ***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 32: 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?
- A. Dissociative identity disorder
- B. Acute stress disorder
- C. Dissociative amnesia with dissociative fugue (Correct Answer)
- D. PTSD
Explanation: ***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.