The Ham test is specifically used for diagnosing paroxysmal nocturnal hemoglobinuria (PNH) and is based upon:
The tissue of origin of the Kaposi's sarcoma is
What is the key pathophysiological difference between acid and alkali injuries in terms of tissue necrosis?
Which one of the following statements is false about Xanthogranulomatous pyelonephritis in children?
Plaques jaunes are seen in which condition?
Alzheimer type II astrocytes are seen in which condition?
Which of the following statements about cross-matching of blood is false?
What is the number of Barr bodies present in Klinefelter's syndrome?
Which of the following testicular tumours is NOT a germ cell tumour?
Medulloblastoma arises exclusively from the cells of
NEET-PG 2015 - Pathology NEET-PG Practice Questions and MCQs
Question 71: The Ham test is specifically used for diagnosing paroxysmal nocturnal hemoglobinuria (PNH) and is based upon:
- A. GPI Anchor Proteins
- B. Complement (Correct Answer)
- C. Spectrin protein
- D. Mannose binding proteins
Explanation: ***Complement*** - The HAM test is based on the activation of the **complement system** which enhances the opsonization and clearance of immune complexes [1]. - It is used in the diagnosis of certain conditions, notably those associated with **hemolytic anemia** due to complement fixation. *GPI Anchor Proteins* - GPI anchor proteins are involved in anchoring proteins to cell membranes but are **not related to the HAM test**. - This oes not explain the **mechanism** or purpose of the HAM test. *Mannose binding proteins* - Mannose binding lectins play a role in **innate immunity** but are not the basis of the HAM test. - They function in the **opsonization of pathogens**, which is unrelated to the complement activation aspect of the HAM test. *Spectrin protein* - Spectrin is a cytoskeletal protein that contributes to the integrity of cell membranes, particularly in red blood cells. - It does not relate to the **mechanism of the HAM test**, which focuses on complement involvement. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 99-100.
Question 72: The tissue of origin of the Kaposi's sarcoma is
- A. Lymphoid
- B. Vascular (Correct Answer)
- C. Neural
- D. Muscular
Explanation: ***Vascular*** - Kaposi's sarcoma originates from the **vascular tissue**, specifically from endothelial cells lining blood vessels [2]. - The lesions are characterized by **angiogenesis**, leading to the formation of vascular tumors with dilated endothelial cell-lined vascular spaces [1]. *Muscular* - Muscular tissue is involved in **voluntary** and **involuntary movements** but is not related to the etiology of Kaposi's sarcoma. - This condition does not arise from **muscle cells** or any muscular components. *Neural* - Neural tissue consists of **neurons** and **glial cells**, which are not implicated in Kaposi's sarcoma. - Kaposi's sarcoma does not originate from any **neural structures** or pathologies. *Lymphoid* - Lymphoid tissue primarily concerns the immune system, particularly the **lymphatic system**, and does not give rise to Kaposi's sarcoma. - This malignancy does not derive from **lymphoid components** like lymphocytes or lymph nodes. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 526-527. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 282-283.
Question 73: What is the key pathophysiological difference between acid and alkali injuries in terms of tissue necrosis?
- A. Acid injuries cause coagulative necrosis
- B. Alkali injuries lead to deeper tissue damage
- C. Acid injuries are less severe than alkali injuries
- D. Alkali injuries cause liquefactive necrosis (Correct Answer)
Explanation: ***Alkali injuries cause liquefactive necrosis*** - **Alkali burns** result in **liquefaction necrosis**, which involves the dissolution of tissue and cells, leading to a much deeper and progressive injury as the alkali penetrates further into tissues. - This is the **key pathophysiological difference** that distinguishes alkali from acid injuries - the TYPE of necrosis (liquefactive vs coagulative). - This type of necrosis allows the alkali to continue damaging underlying tissues and can lead to more extensive and severe scarring and complications. *Acid injuries cause coagulative necrosis* - While this statement is **medically true**, it only describes what acids do without explicitly stating the **difference** or comparison with alkali injuries. - The question asks for the KEY **difference**, and this option presents only one half of the comparison. - **Acid burns** typically cause **coagulation necrosis**, forming a coagulum or eschar that precipitates proteins and creates a barrier, thereby limiting the depth of penetration. - The correct answer (alkali → liquefactive necrosis) better captures the distinguishing pathophysiological feature. *Alkali injuries lead to deeper tissue damage* - This statement is true but serves as a **consequence** of the underlying **liquefactive necrosis** rather than the primary pathophysiological mechanism itself. - The liquefaction process continuously destroys cells and extracellular matrix, enabling the caustic agent to propagate deeply into the tissue. - This describes the OUTCOME rather than the KEY pathophysiological mechanism. *Acid injuries are less severe than alkali injuries* - This is a **generalization about severity** rather than identifying the specific pathophysiological mechanism of tissue death. - While generally true due to the **coagulation necrosis** limiting the depth of penetration of acids, severity can vary based on concentration, duration of exposure, and other factors. - The formation of a protective eschar in acid burns often prevents further significant tissue destruction, unlike the progressive damage seen in alkali burns.
Question 74: Which one of the following statements is false about Xanthogranulomatous pyelonephritis in children?
- A. Clinical presentation in children is the same as in adults
- B. Boys are affected more frequently (Correct Answer)
- C. Often affects those younger than 8 years of age
- D. It affects the kidney diffusely more frequently than focally
Explanation: ***Boys are affected more frequently*** - This statement is **false** for xanthogranulomatous pyelonephritis (XGP) in children. XGP typically shows a **female predominance** in children, similar to adults. - The disease is more common in girls due to the higher incidence of **urinary tract infections** and **urinary obstruction** in females. *It affects the kidney diffusely more frequently than focally* - This statement is **true**. XGP predominantly presents as a **diffuse disease** affecting the entire kidney in approximately **80-90% of cases**. - **Focal XGP** (10-20% of cases) can occur and may mimic a renal tumor, but diffuse involvement is the classic and more common presentation in both adults and children [1]. *Clinical presentation in children is the same as in adults* - This statement is **true**. Children with XGP often present with similar symptoms to adults, including **fever**, **flank pain**, **recurrent urinary tract infections**, and a **palpable abdominal mass** [1]. - **Failure to thrive** and **anemia** are also common in pediatric cases, reflecting the chronic nature of the infection. *Often affects those younger than 8 years of age* - This statement is **true**. XGP, when it occurs in children, often presents in the **younger age group**, typically before 8 years of age. - This demographic observation highlights the importance of considering XGP in young children with persistent urinary tract symptoms and imaging abnormalities. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 939-940.
Question 75: Plaques jaunes are seen in which condition?
- A. Syphilis
- B. Head injury
- C. Endocarditis
- D. Atherosclerosis (Correct Answer)
Explanation: ***Head injury*** - **Plaques jaunes**, or yellow plaques, are primarily associated with brain injuries, particularly in areas of **contusion** or **hemorrhage** [1]. - These plaques may represent **lipid-laden macrophages** and indicate areas of *necrosis* and inflammation in the brain [1]. *Endocarditis* - Endocarditis is characterized by **vegetations** on heart valves rather than plaques in the brain. - Symptoms typically include **fever**, **murmurs**, and **embolization**, which do not involve yellow plaques. *Syphilis* - Syphilis may cause *gummatous lesions* but is not associated with yellow plaques in the brain. - Typical findings include **rash** and **ulcerative lesions**, particularly during the secondary stage. *Atherosclerosis* - Atherosclerosis involves **plaque formation** in blood vessels but these are not the same as **plaques jaunes** in neurological contexts. - It is characterized by **cholesterol** deposits and plaque rupture leading to cardiovascular events, not plaques seen in head injuries. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1262-1264.
Question 76: Alzheimer type II astrocytes are seen in which condition?
- A. Hepatic encephalopathy (Correct Answer)
- B. Parkinsonism
- C. Alzheimer's
- D. Binswanger disease
Explanation: ***Hepatic encephalopathy*** - **Alzheimer type II astrocytes** are characteristic histological findings in cases of **hepatic encephalopathy**, reflecting the brain's response to elevated ammonia levels. - These astrocytes show enlarged, pale nuclei with prominent nucleoli and marginal chromatin, indicating cellular stress from metabolic dysfunction in the setting of liver failure. *Alzheimer's* - Alzheimer's disease is characterized by the presence of **neurofibrillary tangles** (tau protein) and **amyloid plaques** (beta-amyloid protein), not Alzheimer type II astrocytes. - Astrocytes in Alzheimer's disease may show reactive changes, but they do not typically manifest as the specific "Alzheimer type II" morphology. *Parkinsonism* - Parkinsonism is primarily characterized by the degeneration of **dopaminergic neurons** in the substantia nigra and the presence of **Lewy bodies** (alpha-synuclein aggregates). - While glial cells (astrocytes and microglia) do play a role in neuroinflammation in Parkinson's, they do not exhibit the specific Alzheimer type II astrocytic change. *Binswanger disease* - Binswanger disease is a form of **vascular dementia** characterized by diffuse white matter lesions due to chronic ischemia and damage to small cerebral blood vessels. - The pathology primarily involves demyelination and axonal loss in the white matter, with reactive gliosis, but not the specific changes seen in Alzheimer type II astrocytes.
Question 77: Which of the following statements about cross-matching of blood is false?
- A. Mandatory in all cases except emergency
- B. Involves visible agglutination
- C. Recipient serum is tested against donor packed cells
- D. Donor serum is tested against recipient packed cells (Correct Answer)
Explanation: ***Donor serum is tested against recipient packed cells*** - This statement is **FALSE** and describes a **minor crossmatch**, which is rarely performed in modern transfusion practice. - The minor crossmatch tests donor antibodies against recipient cells, but this is not standard practice because donor plasma is significantly diluted during transfusion, making clinically significant reactions rare. - Modern blood banking focuses on the **major crossmatch** as the critical safety measure. *Recipient serum is tested against donor packed cells* - This statement is **TRUE** and accurately describes the **major crossmatch**, which is the standard and most critical pre-transfusion compatibility test. - The major crossmatch detects antibodies in the recipient's serum that could react with donor red blood cell antigens, preventing potentially fatal hemolytic transfusion reactions. *Mandatory in all cases except emergency* - This statement is **TRUE**. Crossmatching is mandatory for safe transfusion practice. - In life-threatening emergencies where delay could be fatal, uncrossmatched O-negative (universal donor) blood may be given, but this is a rare exception. *Involves visible agglutination* - This statement is **TRUE**. A positive crossmatch indicating incompatibility is identified by **visible agglutination** or **hemolysis**. - These visible reactions occur when recipient antibodies bind to donor red blood cell antigens, signaling that transfusion would cause a severe reaction.
Question 78: What is the number of Barr bodies present in Klinefelter's syndrome?
- A. 0
- B. 1 (Correct Answer)
- C. 2
- D. 3
Explanation: ***1*** - **Klinefelter's syndrome** typically has a 47,XXY karyotype, meaning there are two X chromosomes [1]. - The number of Barr bodies is calculated as **N-1**, where N is the total number of X chromosomes. In this case, 2-1 = **1 Barr body** [1]. - This follows the principle that one X chromosome remains active while additional X chromosomes are inactivated [1]. *0* - **No Barr bodies** are found in individuals with a normal male karyotype (46,XY) or in Turner syndrome (45,XO), neither of which describes Klinefelter's syndrome [1]. - The presence of at least one Barr body indicates the presence of at least two X chromosomes. *2* - **Two Barr bodies** would be indicative of a karyotype with three X chromosomes (e.g., 47,XXX syndrome or Triple X syndrome), which is not Klinefelter's syndrome. - This calculation follows the N-1 rule: 3 X chromosomes - 1 = 2 Barr bodies. *3* - **Three Barr bodies** would correspond to a karyotype with four X chromosomes (e.g., 48,XXXX), which is an even rarer sex chromosome aneuploidy not associated with Klinefelter's syndrome. - The N-1 rule applies: 4 X chromosomes - 1 = 3 Barr bodies. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 173-174.
Question 79: Which of the following testicular tumours is NOT a germ cell tumour?
- A. Seminoma
- B. Teratoma
- C. Choriocarcinoma
- D. Sertoli cell tumour (Correct Answer)
Explanation: ***Sertoli cell tumour*** - This is a **sex-cord stromal tumour**, not a germ cell tumour, hence it does not arise from germ cells. - Sertoli cell tumours typically present with abnormal hormone levels, but not the classic germ cell tumour markers. *Choriocarcinoma* - This is a **germ cell tumour** that is aggressive and associated with high levels of **beta-hCG** [1][2]. - It derives from the placental tissue and is characterized by **trophoblastic differentiation** [2]. *Seminoma* - A well-known type of **germ cell tumour**, often presenting as a **homogeneous testicular mass** [1]. - It usually manifests with elevated **LDH** and is associated with a more favorable prognosis compared to non-seminomatous germ cell tumours [1]. *Teratoma* - Teratomas are also classified as **germ cell tumours**, containing differentiated tissues like hair, muscle, and bone [1][2]. - They can be **mature** (benign) or **immature** (malignant), and are typically found in younger patients [2][3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 979-980. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 982-983. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 512-513.
Question 80: Medulloblastoma arises exclusively from the cells of
- A. Immature embryonal cells (Correct Answer)
- B. Ependymal cells
- C. Neurons
- D. Spindle-shaped cells
Explanation: ***Immature embryonal cells*** - **Medulloblastoma** is a malignant **embryonal tumor** of the cerebellum, exclusively arising from primitive neuroectodermal cells. - These tumors are thought to originate from remnants of the **external granular layer** of the cerebellum or other primitive neuroectodermal cells. *Ependymal cells* - Tumors arising from **ependymal cells** are called **ependymomas**, which typically occur within the ventricles of the brain or spinal cord. - Ependymomas have distinct histological features and clinical behavior compared to medulloblastomas. *Neurons* - Tumors primarily composed of neurons or with significant neuronal differentiation include **gangliogliomas** and **central neurocytomas**. - **Medulloblastomas** largely consist of undifferentiated, small round cells with minimal evidence of neuronal maturation. *Spindle-shaped cells* - **Spindle-shaped cells** are characteristic of various tumor types, including some **gliomas** (e.g., pilocytic astrocytoma) or mesenchymal tumors. - While some medulloblastoma variants can show desmoplastic features, the hallmark cell type is a small, round, blue embryonal cell.