Bone and Soft Tissue Pathology — MCQs

Bone and Soft Tissue Pathology Indian Medical PG Practice Questions and MCQs

Question 331: What is the most common malignant tumor of the skeletal system?

A. Chondrosarcoma
B. Multiple myeloma
C. Osteosarcoma
D. Metastasis (Correct Answer)

Explanation: ***Metastasis*** - **Skeletal metastasis** is overwhelmingly the most common malignant tumor involving bone, as many primary cancers (e.g., breast, prostate, lung) frequently spread to bone [1]. - While not originating in the bone, these metastatic deposits are malignant neoplasms within the skeletal system, making them the most prevalent. *Multiple myeloma* - This is a **primary malignancy of plasma cells** that arises in the bone marrow, causing destructive bone lesions. - It is the most common **primary malignant bone tumor** in adults, but still less common than metastatic disease. *Osteosarcoma* - This is the most common **primary malignant bone tumor** in **children and adolescents**, primarily affecting long bones [2]. - While a significant primary bone cancer, its incidence is lower than that of metastatic bone disease across all age groups [1]. *Chondrosarcoma* - This is a malignant tumor of **cartilage-forming cells** and is the second most common primary bone cancer in adults, after multiple myeloma [3]. - It is much less common than metastatic disease and osteosarcoma [1], [3]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 671-672. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1202. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1204.

Question 332: 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 333: 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 334: What are the common causes of vertebra plana?

A. Eosinophilic granuloma
B. Metastatic disease
C. Tuberculosis
D. All of the options (Correct Answer)

Explanation: ***All of the options*** - **Vertebra plana** refers to the severe flattening of a vertebral body, often caused by a destructive lesion, and all listed options are known causes. [5] - While **eosinophilic granuloma** is a classic cause, **metastatic disease** and **tuberculosis** can also lead to significant vertebral collapse. [3], [5] *Eosinophilic granuloma* - This is a benign condition, a form of **Langerhans cell histiocytosis**, which commonly affects children and can cause vertebra plana. [1] - It results from proliferative lesions of **Langerhans cells** that infiltrate the bone, leading to its destruction and collapse. [1] *Metastatic disease* - **Malignant tumors** often spread to the spine, causing osteolytic lesions that weaken the vertebral body. [4], [5] - The destruction caused by metastatic deposits can lead to **vertebral collapse** and associated pain. [5] *Tuberculosis* - **Tuberculosis of the spine (Pott's disease)** is an infectious inflammatory condition that can severely damage vertebral bodies. [2], [3] - The granulomatous inflammation and caseous necrosis can erode the bone, leading to **vertebral collapse** and kyphosis. [2] **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, p. 630. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1197-1198. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 669-670. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 724-725. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 671-672.

Question 335: In which condition is pannus formation typically observed?

A. RA (Correct Answer)
B. Osteoarthritis (OA)
C. Gout (Gouty Arthritis)
D. Psoriatic Arthritis (PsA)

Explanation: ***RA*** - **Pannus** is a characteristic feature of **rheumatoid arthritis**, representing an aggressive, hyperplastic synovial tissue that invades and destroys cartilage and bone [1], [2]. - This destructive granulation tissue primarily consists of fibroblasts, macrophages, and inflammatory cells, contributing to joint erosion [1]. *Osteoarthritis (OA)* - While **osteophytes** (bone spurs) and **cartilage degradation** are hallmarks of OA, **pannus formation** is not seen. - OA involves breakdown of articular cartilage due to mechanical stress and biochemical changes, not synovial invasion. *Gout (Gouty Arthritis)* - Gout is characterized by the deposition of **monosodium urate crystals** in joints, leading to acute inflammation [4]. - The formation of **tophi** (urate crystal deposits) is typical, but not **pannus** [4]. *Psoriatic Arthritis (PsA)* - PsA can cause joint inflammation and erosion similar to RA but does not typically involve the extensive **pannus formation** characteristic of RA [3]. - Specific features of PsA include **enthesitis**, dactylitis and involvement of **DIP joints** [3]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 677-678. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1212. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1214-1215. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1218.

Question 336: Sequestrum is best defined as

A. A piece of dead bone surrounded by infected tissue (Correct Answer)
B. A piece of dead bone without surrounding infection
C. A piece of bone with compromised blood supply
D. None of the options

Explanation: ***A piece of dead bone surrounded by infected tissue*** * A sequestrum is a fragment of **necrotic (dead) bone** that has become separated from the surrounding living bone in the context of **chronic osteomyelitis**. * The dead bone is typically surrounded by **infected granulation tissue and pus**, making it the classic definition taught in the context of bone infections. * The sequestrum acts as a **nidus for persistent infection**, as antibiotics cannot penetrate the avascular dead bone, making surgical removal often necessary. *A piece of dead bone without surrounding infection* * While a sequestrum is fundamentally dead bone, in clinical practice and standard teaching, it is **intrinsically associated with infection** in osteomyelitis. * The phrase "without surrounding infection" makes this option incorrect, as the classic sequestrum occurs in the **inflammatory milieu of chronic osteomyelitis**. *A piece of bone with compromised blood supply* * This describes **ischemic or avascular bone**, which is the **initial pathological event** that leads to bone death. * However, this is not the definition of sequestrum itself—the sequestrum is the **end result** (dead bone fragment) rather than bone with compromised vascularity. * A sequestrum has **no blood supply** (completely avascular), not merely compromised supply. *None of the options* * This is incorrect because the first option accurately captures the **standard definition of sequestrum** as taught in the context of chronic osteomyelitis in medical education.

Question 337: Which of the following is true about Giant cell tumor?

A. Epiphyseal origin (Correct Answer)
B. Seen in age less than 15 years
C. Usually presents as a lytic lesion without a sclerotic rim.
D. Always benign

Explanation: ***Epiphyseal origin*** - Giant cell tumors (GCTs) characteristically arise in the **epiphysis** or **metaphysis** of long bones, often extending into the subchondral bone [1]. - This distinguishes them from many other bone tumors that typically originate in the diaphysis or metaphysis. *Always benign* - While GCTs are predominantly **benign**, they have a significant potential for **local recurrence** and, in rare cases, can undergo **malignant transformation** or metastasize to the lungs. - Therefore, they are considered to have an **intermediate biological potential**, not strictly benign. *Seen in age less than 15 years* - GCTs are most commonly observed in **young adults**, typically between the ages of 20 and 40 years, after **skeletal maturity**. - They are exceedingly **rare** in individuals younger than 15 years, as the epiphyses are still open. *Usually presents as a lytic lesion without a sclerotic rim* - GCTs are indeed **lytic lesions**, appearing as areas of bone destruction without a significant periosteal reaction or sclerosis, giving them a **"soap-bubble" appearance**. - However, they often have a **thin sclerotic rim** in some parts of the lesion, especially at the margins, which helps differentiate them from more aggressive lesions [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1205-1206.

Question 338: Glomus tumor is seen in -

A. Rare locations such as retroperitoneum
B. Long bones and vertebrae
C. Proximal portion of digits (less common site)
D. Distal portion of digits (Correct Answer)

Explanation: ***Distal portion of digits*** - **Glomus tumors** are most commonly found in the **distal extremities**, especially the **subungual region** (under the nail) of the fingers and toes. - This location accounts for over 75% of all glomus tumors, where they originate from specialized **neuromyoarterial glomus bodies** involved in thermoregulation. - The classic clinical triad includes **paroxysmal pain, point tenderness, and cold sensitivity**. *Rare locations such as retroperitoneum* - While glomus tumors can occur in unusual sites, the **retroperitoneum** is an exceptionally rare location for primary glomus tumors. - Extradigital glomus tumors account for approximately 25% of cases and can occur in various soft tissue sites. *Long bones and vertebrae* - Glomus tumors do not typically arise in **bone tissue** as they originate from glomus bodies in soft tissue. - Bone involvement, when present, is usually secondary due to pressure erosion from an adjacent soft tissue tumor rather than primary bone origin. *Proximal portion of digits (less common site)* - While glomus tumors can occasionally be found in less common digital locations, the **proximal portion of digits** is significantly less frequent than the distal, and particularly the subungual, region. - Their primary association remains with the **distal phalanx** and nail bed.

Question 339: Tadpole cells, comma-shaped cells on histopathology are seen in -

A. Trichoepithelioma
B. Rhabdomyosarcoma (Correct Answer)
C. Histiocytoma
D. Leiomyosarcoma

Explanation: ***Rhabdomyosarcoma*** - **Tadpole cells** and **comma-shaped cells** are characteristic histological features of **rhabdomyosarcoma**, representing primitive mesenchymal cells differentiating towards skeletal muscle. - These cells are often pleomorphic, with eccentric nuclei and fibrillar eosinophilic cytoplasm, giving them their distinctive shapes. *Trichoepithelioma* - This is a benign adnexal tumor of follicular differentiation, characterized by nests of **basaloid cells**, **horn cysts**, and rudimentary hair structures. - It does not typically feature tadpole or comma-shaped cells. *Histiocytoma* - A **benign fibrous histiocytoma** (dermatofibroma) is composed of fibroblasts and histiocytes forming storiform patterns. - **Malignant fibrous histiocytoma** (now often reclassified as undifferentiated pleomorphic sarcoma) features pleomorphic spindle cells and giant cells, but not specifically tadpole or comma-shaped cells. *Leiomyosarcoma* - This is a malignant tumor of **smooth muscle origin**, characterized by spindle cells with blunt-ended nuclei, arranged in fascicles. - It lacks the tadpole or comma-shaped cells seen in rhabdomyosarcoma.

Question 340: Ewing's sarcoma arises from which type of cells?

A. G cells
B. Totipotent cells
C. Neurons
D. Primitive neuroectodermal cells (Correct Answer)

Explanation: ***Primitive neuroectodermal cells*** - **Ewing's sarcoma** is a malignant small round blue cell tumor largely believed to arise from **primitive neuroectodermal cells**. - This cellular origin explains why it's often grouped under the term **PNET (Primitive Neuroectodermal Tumor)**. *G cells* - **G cells** are specialized **enteroendocrine cells** found in the stomach and duodenum that secrete **gastrin**. - They are involved in regulating gastric acid secretion and have no association with Ewing's sarcoma. *Totipotent cells* - **Totipotent cells** have the ability to differentiate into **any type of cell**, including embryonic and extraembryonic tissues. - While all cancers originate from cellular changes, Ewing's sarcoma originates from a more specific, committed cell lineage, not totipotent stem cells. *Neurons* - **Neurons** are the basic functional units of the nervous system, responsible for transmitting electrical and chemical signals. - While Ewing's sarcoma has neuroectodermal characteristics, it does not arise from fully differentiated neurons but rather from more **primitive precursors**.

Practice by Chapter

Bone Development and Growth

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Fracture Healing

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Osteomyelitis and Infectious Diseases

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Metabolic Bone Diseases

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Bone Tumors and Tumor-like Lesions

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Joints and Rheumatologic Diseases

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Soft Tissue Tumors

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Muscular Dystrophies and Myopathies

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Diseases of Tendons and Fascia

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Pathology of Orthopedic Implants

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