What is a watershed infarct in the brain?
Renal stones which are laminated and irregular in outline are
Brown tumors are seen in:
In Articular cartilage, most active chondrocytes are seen in ?
Which of the following is a premalignant lesion for carcinoma of the rectum?
Most significant risk factor for development of gastric carcinoma is
All are features of Paget's disease except which of the following?
Calcified pulmonary metastasis is seen in which carcinoma?
Which of the following statements about chronic osteomyelitis is false?
Which layer of the epidermis is primarily involved in spongiosis?
NEET-PG 2013 - Pathology NEET-PG Practice Questions and MCQs
Question 61: What is a watershed infarct in the brain?
- A. Occurs in the border zones between major arteries (Correct Answer)
- B. Occurs in the areas supplied by only one artery
- C. Occurs in the terminal portion of main arteries
- D. Occurs only in areas with complete arterial occlusion
Explanation: ***Occurs in the border zones between major arteries*** - A **watershed infarct** or **border zone infarct** arises in areas where the **perfusion** from two different arterial territories meets [1]. - These areas are particularly vulnerable to ischemia during periods of **systemic hypoperfusion**, as blood flow is lowest at the "watershed" of these overlapping supply zones [1]. *Occurs in the areas supplied by only one artery* - Infarcts in areas supplied by only one artery are typically seen in **lacunar strokes**, affecting **deep penetrating arteries** and not necessarily watershed areas [2]. - These are often due to occlusion of a single, small perforating artery, leading to a **discrete, localized lesion**. *Occurs only in areas with complete arterial occlusion* - Watershed infarcts result from **systemic hypoperfusion** rather than complete arterial occlusion [1]. - They occur when global reduction in cerebral blood flow affects the **most vulnerable border zones**, even without complete vessel occlusion. - Complete arterial occlusions typically cause **territorial infarcts** in the distribution of that specific artery. *Occurs in the terminal portion of main arteries* - Infarcts in the terminal portions of main arteries are more consistent with **embolic or thrombotic events** directly occluding that specific artery. - A watershed infarct is distinct as it results from a **global reduction in cerebral blood flow**, affecting the *most distal* and *least well-perfused regions*. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 150-151. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1266-1268.
Question 62: Renal stones which are laminated and irregular in outline are
- A. Uric acid
- B. Calcium oxalate (Correct Answer)
- C. Struvite
- D. Cystine
Explanation: ***Calcium oxalate*** - **Calcium oxalate stones** are the most common type of kidney stones and characteristically present with a **laminated** (layered) and **irregular, spiculated outline** due to their crystalline structure - They are typically **radio-opaque** on X-rays due to their calcium content - The irregular outline distinguishes them from other stone types *Uric acid* - **Uric acid stones** are often **smooth**, hard, and **yellowish-brown** in appearance - They are **radio-lucent** on standard X-rays and are associated with conditions like gout or acidic urine - Their smooth surface contrasts with the irregular calcium oxalate stones *Struvite* - **Struvite stones** (magnesium ammonium phosphate) are strongly associated with **urinary tract infections** (UTIs) and can form **staghorn calculi**, filling the renal pelvis - They tend to be **friable** and have a **smooth or glistening** surface, often growing quite large - Associated with urease-producing bacteria *Cystine* - **Cystine stones** are caused by a genetic disorder affecting amino acid transport and generally appear **smooth, waxy, and hexagonal crystal-shaped** - They are typically **moderately radio-opaque** but less dense than calcium stones - The smooth, waxy appearance differs from the irregular calcium oxalate stones
Question 63: Brown tumors are seen in:
- A. Pigmented villonodular synovitis
- B. Osteomalacia
- C. Neurofibromatosis
- D. Hyperparathyroidism (Correct Answer)
Explanation: ***Hypeparathyroidism*** - Brown tumors, also called osteitis fibrosa cystica, are **osteolytic lesions** associated specifically with **hyperparathyroidism** due to increased osteoclastic activity [1][2]. - Elevated levels of **parathyroid hormone (PTH)** lead to bone resorption, giving rise to the characteristic bone changes seen in this condition [1][2]. *Neurofibromatosis* - Neurofibromatosis primarily presents with **neurofibromas**, café-au-lait spots, and skin-related findings, not with brown tumors. - Bone manifestations include **scoliosis** or **plexiform neurofibromas**, but they do not typically lead to brown tumors. *Pigmented villonodular synovitis* - This is a **joint condition** featuring hyperplastic synovial tissue and local joint swelling, but it does not involve **bone changes** typical of brown tumors. - Characterized by **pigmented nodules** in the synovium, it doesn't cause osteolytic lesions seen in hyperparathyroidism. *Osteomalacia* - Osteomalacia is primarily due to **vitamin D deficiency**, leading to softening of the bones, not the formation of **brown tumors**. - It results in bone pain and weakness, with radiological changes such as **Looser's zones** rather than the well-defined lucencies associated with brown tumors. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1105-1106. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1194.
Question 64: In Articular cartilage, most active chondrocytes are seen in ?
- A. Zone 1
- B. Zone 4
- C. Zone 3
- D. Zone 2 (Correct Answer)
Explanation: ***Zone 2*** - This is the **transitional (or middle) zone**, where chondrocytes are numerous and more metabolically active, responsible for synthesizing major components of the extracellular matrix. - Chondrocytes here are typically **ovoid or round**, arranged somewhat randomly, and are involved in maintaining the cartilage structure. *Zone 1* - This is the **superficial (or tangential) zone**, where chondrocytes are **flattened** and oriented parallel to the articular surface. - Their primary role is to resist shear forces, and they are generally less metabolically active compared to those in the transitional zone. *Zone 3* - This is the **deep (or radial) zone**, characterized by **columnar arrangements** of chondrocytes. [1] - While these chondrocytes are metabolically active and synthesize matrix components, they are generally less active than those in the transitional zone and are more involved in resisting compressive forces. *Zone 4* - This is the **calcified zone**, directly adjacent to subchondral bone, where chondrocytes are **sparse** and often hypertrophic prior to eventual calcification. - This zone acts as an interface between cartilage and bone, and its chondrocytes have significantly reduced metabolic activity once calcification occurs. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1184.
Question 65: Which of the following is a premalignant lesion for carcinoma of the rectum?
- A. Juvenile polyposis
- B. Adenomatous polyps (Correct Answer)
- C. Familial adenomatous polyposis
- D. Hyperplastic polyps
Explanation: ***Familial polyposis*** - Familial adenomatous polyposis (FAP) is characterized by numerous **adenomatous polyps** in the colon and rectum, which have a high risk of progressing to colorectal cancer [1]. - Individuals with FAP are at significant risk for developing **carcinoma rectum** at a young age if the condition is not managed properly [1]. *Juvenile polyp* - Juvenile polyps are generally **benign** and occur in children, with a very low risk of malignancy. - They do not contribute significantly to the risk of **carcinoma rectum** like adenomatous polyps do. *Adenomatous polyp* - While adenomatous polyps are indeed premalignant [1], the term **Familial polyposis** indicates a hereditary condition that specifically has a higher and more defined risk for rectal carcinoma. - Adenomatous polyps can occur sporadically and do not imply a genetic syndrome like familial polyposis. *FAP* - FAP refers specifically to **familial adenomatous polyposis** [1], which is the same concept as familial polyposis but less encompassed in terms of broad assessment in this context. - It is important to note that **familial polyposis** is a broader term that includes conditions like FAP and indicates a significant risk factor for rectal cancer [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 817, 821-822.
Question 66: Most significant risk factor for development of gastric carcinoma is
- A. Pyloric metaplasia
- B. Intestinal metaplasia (Correct Answer)
- C. Ciliated metaplasia
- D. Paneth cell metaplasia
Explanation: ***Intestinal metaplasia*** - **Intestinal metaplasia** is a precursor lesion where gastric epithelium is replaced by intestinal-type epithelium, significantly increasing the risk for **gastric carcinoma** [1][2]. - It is a recognized **high-risk factor**, especially in cases of chronic gastritis and atrophic changes in the stomach lining [1][2]. *Ciliated metaplasia* - This condition is generally associated with **respiratory epithelium** and is not linked to gastric carcinoma risk. - It does not involve gastric epithelial changes, therefore, it does not influence **gastric cancer development**. *Pyloric metaplasia* - Pyloric metaplasia typically occurs in chronic gastritis but does not confer a significant **risk** of gastric carcinoma. - It is more related to gastric mucosa adaptation and does not show the same risk association as **intestinal metaplasia**. *Paneth cell metaplasia* - Paneth cell metaplasia is primarily seen in **intestinal disorders** and does not serve as an indicator for gastric carcinoma. - It does not reflect changes in gastric epithelium that are related to cancer risk in the stomach. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 777-778. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 354-355.
Question 67: All are features of Paget's disease except which of the following?
- A. Defect in osteoclasts
- B. Affects only axial skeleton (Correct Answer)
- C. Can lead to hearing loss
- D. Can lead to bone cancer
Explanation: ***Affects only axial skeleton*** - This statement is **FALSE** and therefore the correct answer to this "EXCEPT" question. - Paget's disease **can affect any bone in the body**, including both axial skeleton (spine, skull, pelvis) and appendicular skeleton (femur, tibia, humerus) [1]. - Common sites include: **pelvis (70%), spine, skull, femur, and tibia** [1]. - While it frequently affects axial bones, it is **not exclusive** to them. *Defect in osteoclasts* - This is a TRUE feature of Paget's disease. - The disease is characterized by **abnormal, hyperactive osteoclasts** with increased number of nuclei (up to 100 vs normal 3-5). - These osteoclasts show **excessive bone resorption activity** followed by disorganized bone formation [1]. - The primary defect involves **increased osteoclast activity and sensitivity to RANKL**. *Can lead to hearing loss* - This is a TRUE feature of Paget's disease. - Skull involvement can lead to **compression of cranial nerve VIII** (vestibulocochlear nerve) [1]. - Enlargement and disorganization of temporal bone can cause **conductive or sensorineural hearing loss**. - Occurs in approximately 30-50% of patients with skull involvement. *Can lead to bone cancer* - This is a TRUE feature of Paget's disease. - **Osteosarcoma** develops in approximately **1%** of Paget's disease patients. - Risk is higher in patients with **polyostotic disease** and long-standing involvement. - This is a rare but serious complication with poor prognosis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1192-1194.
Question 68: Calcified pulmonary metastasis is seen in which carcinoma?
- A. Pancreatic carcinoma
- B. Thyroid carcinoma (Correct Answer)
- C. Endometrial carcinoma
- D. None of the options
Explanation: ***Thyroid carcinoma*** - **Papillary** and **medullary thyroid carcinomas** can produce **calcified pulmonary metastases**. - In **papillary thyroid cancer**, calcification occurs due to **psammoma bodies** (concentrically laminated calcified structures). - In **medullary thyroid cancer**, calcification can occur through **dystrophic calcification** within the tumor tissue. - Other common causes of calcified lung metastases include **osteosarcoma** and **chondrosarcoma**. *Pancreatic carcinoma* - Pancreatic carcinoma rarely causes **calcified pulmonary metastases**; metastatic lesions are typically **non-calcified**. - Metastases are more commonly found in the **liver** and **peritoneum**. - Primary pancreatic tumors may show calcification, but metastases usually do not. *Endometrial carcinoma* - Endometrial carcinoma metastases to the lungs are usually **non-calcified** and appear as **soft tissue nodules**. - While it can metastasize to the lungs, **calcification** is not a typical feature of its pulmonary spread. *None of the options* - This option is incorrect because **thyroid carcinoma** (particularly papillary type) is a well-recognized cause of **calcified pulmonary metastases**. - Among epithelial malignancies, thyroid carcinoma is one of the classic causes of this finding.
Question 69: Which of the following statements about chronic osteomyelitis is false?
- A. Reactive new bone formation
- B. Cloaca is an opening in involucrum
- C. Involucrum is dead bone (Correct Answer)
- D. Sequestrum is hard and dense
Explanation: ***Involucrum is dead bone*** - This statement is false because the **involucrum** is the layer of **new bone formation** that surrounds a segment of necrotic (dead) bone, known as the **sequestrum**, in chronic osteomyelitis [1]. - The involucrum represents the body's attempt to wall off the infection and dead bone, and thus, it is living, *reactive bone*, not dead bone [1]. *Reactive new bone formation* - This statement is true; **reactive new bone formation** occurs around infected or necrotic bone in chronic osteomyelitis, forming the **involucrum** [1]. - This process is a hallmark of the body's response to chronic infection and attempts to contain it. *Cloaca is an opening in involucrum* - This statement is true; a **cloaca** is a **fistulous tract** or opening in the **involucrum** that allows pus and necrotic debris from the infected area to drain to the skin surface. - This drainage is a common clinical sign of chronic osteomyelitis. *Sequestrum is hard and dense* - This statement is true; the **sequestrum** is a piece of **necrotic (dead) bone** that has become separated from living bone due to ischemia and infection [1]. - Due to the loss of blood supply and avascular necrosis, it appears **dense, hard, and radiodense** on imaging, representing devitalized bone tissue that is walled off from the body's immune response. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1197-1198.
Question 70: Which layer of the epidermis is primarily involved in spongiosis?
- A. Stratum basale
- B. Stratum corneum
- C. Stratum granulosum
- D. Stratum spinosum (Correct Answer)
Explanation: ***Stratum spinosum*** - **Spongiosis** is characterized by **intercellular edema** (fluid accumulation between cells) within the epidermis [1], primarily affecting the **stratum spinosum** [2]. - The cells of the stratum spinosum, known as **keratinocytes**, become separated by this edema, giving the tissue a "spongy" appearance on histology due to the preservation of **desmosomal attachments**. *Stratum basale* - The **stratum basale** is the deepest layer of the epidermis, responsible for **cell proliferation** and attachment to the basement membrane. - While edema can affect all epidermal layers in severe cases, spongiosis specifically refers to the intercellular edema most prominent in the stratum spinosum [2]. *Stratum corneum* - The **stratum corneum** is the outermost layer of the epidermis, composed of dead, flattened **keratinocytes** that provide a protective barrier. - Edema in this layer is less common and would not be described as spongiosis, which implies living cells with preserved intercellular junctions. *Stratum granulosum* - The **stratum granulosum** lies above the stratum spinosum and is characterized by cells containing **keratohyalin granules**. - While it can be affected by intercellular edema, the most pronounced and characteristic spongiosis occurs in the stratum spinosum where cells are still actively synthesizing keratin and have strong desmosomal connections [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Disorders Involving Inflammatory And Haemopoietic Cells, p. 636. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, p. 1166.