Bone and Soft Tissue Pathology — MCQs

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

Question 301: Chondrocalcinosis is seen in -

A. Ochronosis
B. Hypoparathyroidism (Correct Answer)
C. Hypervitaminosis D
D. Rickets

Explanation: ***Hypoparathyroidism*** - **Hypoparathyroidism** is a **classic metabolic cause** of **chondrocalcinosis** due to altered calcium and phosphate metabolism leading to deposition of **calcium pyrophosphate dihydrate (CPPD) crystals** in cartilage [1]. - The deficiency of parathyroid hormone (PTH) results in **hypocalcemia** and **hyperphosphatemia**, promoting crystal formation and pseudogout [3]. - This is a **commonly tested association** in medical examinations and represents a more frequent clinical scenario [1]. *Ochronosis* - **Ochronosis** (alkaptonuria) is a rare genetic disorder characterized by accumulation of **homogentisic acid** polymers in connective tissues, causing bluish-black pigmentation. - While ochronosis **can cause chondrocalcinosis**, it is an extremely rare condition and less commonly associated compared to metabolic disorders. - The primary features are pigmentation and degenerative arthropathy, with chondrocalcinosis being a secondary finding. *Hypervitaminosis D* - **Hypervitaminosis D** leads to **hypercalcemia** and widespread soft tissue calcification, including vascular and renal calcification [2], [4]. - It is **not typically associated** with **CPPD crystal deposition** or chondrocalcinosis in cartilage. - The pattern of calcification differs from the specific cartilaginous deposition seen in chondrocalcinosis. *Rickets* - **Rickets** is caused by **vitamin D deficiency** in children, leading to **impaired bone mineralization** with soft, weak bones and skeletal deformities. - It is characterized by **hypomineralization**, not calcification—the opposite of chondrocalcinosis. - No association with CPPD crystal deposition in cartilage. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 683-684. [2] 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. 134-135. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1194-1195. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Cellular Responses to Stress and Toxic Insults: Adaptation, Injury, and Death, pp. 76-77.

Question 302: Select the type of bone disease which is most likely to be associated with genetically determined disorder in the structure or processing of type I collagen (SELECT 1 DISEASE)

A. Osteogenesis imperfecta (Correct Answer)
B. Osteopetrosis
C. Osteomalacia
D. Osteitis fibrosa cystica

Explanation: ***Osteogenesis imperfecta*** - This condition is primarily caused by **genetic defects** in the production of **type I collagen**, leading to fragile bones. - Due to these defects, bones are prone to **fractures** with minimal trauma. *Osteopetrosis* - Characterized by abnormally **dense bones** due to a defect in **osteoclast function**, not collagen structure [1]. - This leads to bones that are brittle and prone to fracture, but the underlying cause is different from collagen abnormalities [1]. *Osteomalacia* - This refers to the **softening of bones** due to impaired **mineralization**, most commonly from **vitamin D deficiency** or phosphate imbalance. - It does not involve a primary defect in the genetic structure or processing of type I collagen. *Osteitis fibrosa cystica* - This is a bone lesion caused by **severe hyperparathyroidism**, leading to excessive bone resorption and replacement by fibrous tissue and cysts. - It is an endocrine disorder affecting **calcium metabolism**, not a primary collagenopathy. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1188.

Question 303: Which soft tissue sarcoma commonly gives rise to bone secondaries? (PGI June 2008)

A. Osteosarcoma
B. Fibrosarcoma (Correct Answer)
C. Neurofibroma
D. Liposarcoma

Explanation: **Fibrosarcoma** (Historical Answer) - This question reflects older teaching that fibrosarcoma has a propensity for bone metastases - However, **modern evidence** shows fibrosarcoma primarily metastasizes to **lungs (80-90%)**, with bone metastases being uncommon - Among soft tissue sarcomas, **clear cell sarcoma, alveolar soft part sarcoma, and synovial sarcoma** are more characteristically associated with bone metastases [1] - Note: This represents the historical answer from PGI 2008; current pathology references may provide different perspectives *Osteosarcoma* - **Osteosarcoma** is a **primary malignant bone tumor**, not a soft tissue sarcoma - It originates in bone and produces **osteoid matrix** by malignant cells - This option is clearly incorrect as it doesn't meet the question criteria *Neurofibroma* - A **benign tumor** of peripheral nerves composed of Schwann cells, fibroblasts, and mast cells - Being benign, it is **non-metastatic** and does not give rise to bone secondaries - This is not a sarcoma *Liposarcoma* - A malignant tumor of **adipose tissue**, classified as a soft tissue sarcoma [2] - Most commonly metastasizes to **lung and liver** - Bone metastases are uncommon, though **myxoid/round cell liposarcoma** subtype may have slightly higher bone metastatic potential than other subtypes [2] **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1225-1226. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1222-1223.

Question 304: Perifascicular atrophy is seen in -

A. Wilson disease
B. Becker's dystrophy
C. Dermatomyositis (Correct Answer)
D. Polymyositis

Explanation: ***Dermatomyositis*** - **Perifascicular atrophy**, characterized by muscle fiber atrophy predominantly at the periphery of muscle fascicles, is a **pathognomonic microscopic feature** of dermatomyositis [1]. - This specific pattern of atrophy is due to microvascular involvement and **ischemia** affecting the perimysial capillaries and their surrounding muscle fibers [1]. *Wilson disease* - Wilson disease is a **genetic disorder** of copper metabolism, primarily affecting the liver and brain, leading to **neurological symptoms** and **hepatic dysfunction** [3]. - While it can cause muscle weakness due to central nervous system involvement, it does not typically present with perifascicular atrophy on muscle biopsy. *Becker's dystrophy* - Becker's muscular dystrophy is an **X-linked recessive disorder** caused by mutations in the **dystrophin gene**, leading to attenuated but not absent dystrophin [2]. - Muscle biopsy typically shows **fiber size variability**, **internalized nuclei**, and occasional degenerating/regenerating fibers, but not perifascicular atrophy [2]. *Polymyositis* - Polymyositis is an **inflammatory myopathy** that primarily affects the proximal muscles, causing symmetrical weakness. - Muscle biopsy in polymyositis typically shows **endomyosial inflammation** with cytotoxic T-cell infiltration and muscle fiber necrosis, but **lacks perifascicular atrophy** [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1240-1242. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1244-1245. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 394-395.

Question 305: Which of the following is not true about osteosarcoma?

A. Seen in the metaphyseal region of the long bones
B. Lung metastasis is common
C. Secondary osteosarcoma is seen in older age groups
D. Most commonly arises in the epiphyseal region (Correct Answer)

Explanation: ***Most commonly arises in the epiphyseal region*** - This statement is **FALSE** - osteosarcoma most commonly arises in the **metaphyseal region** of long bones, particularly around the knee (distal femur, proximal tibia) and proximal humerus [1]. - The metaphysis is the region where bone growth is most active, which explains why osteosarcoma preferentially occurs there. - The epiphysis (growth plate region) is **not** the typical location for osteosarcoma. *Seen in the metaphyseal region of the long bones* - This is **TRUE** - osteosarcoma characteristically arises in the **metaphyseal regions** of long bones, especially around the knee and proximal humerus where growth is most active [1]. *Lung metastasis is common* - This is **TRUE** - the lungs are the most common site of distant metastasis in osteosarcoma, occurring in up to 80% of patients who develop metastatic disease [1]. - Pulmonary metastasis significantly impacts prognosis and treatment [1]. *Secondary osteosarcoma is seen in older age groups* - This is **TRUE** - while primary osteosarcoma affects children and young adults (peak 10-20 years), **secondary osteosarcoma** occurs in older patients, typically arising in association with Paget's disease, prior radiation therapy, or bone infarcts [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. 1200-1202.

Question 306: Rate of newly synthesized osteoid mineralization can be best estimated by -

A. Calcein stain
B. Tetracycline labeling (Correct Answer)
C. Von Kossa stain
D. Alizarin red stain

Explanation: ***Tetracycline labeling*** - **Tetracycline** is incorporated into newly forming bone (osteoid) at the mineralization front because of its **calcium-chelating properties**. - By administering two doses of tetracycline at a known interval, the distance between the two fluorescent bands can be measured to calculate the **mineralization apposition rate**, which reflects the rate of new osteoid mineralization. *Calcein stain* - **Calcein** is another fluorescent marker that can be used for bone labeling, similar to tetracycline, but it is less commonly used in clinical practice. - While it labels mineralizing bone, the question asks for the **best** method for estimating the *rate* of mineralization, for which tetracycline's historical and established two-dose method is superior. *Von Kossa stain* - The **Von Kossa stain** highlights mineralized bone by precipitating silver in areas where calcium salts are present, thus indirectly staining the mineral component. - It does not directly assess the *rate* of mineralization or the difference between newly synthesized and pre-existing mineralized bone. *Alizarin red stain* - **Alizarin red S** is a dye that stains calcium deposits a red-orange color, making it useful for identifying areas of mineralization. - Like Von Kossa, it indicates the presence of calcium but does not provide a quantitative measure of the *rate* at which newly formed osteoid is mineralizing over time.

Question 307: Osteoporosis is characterized most commonly by:

A. Increased bone density and increased bone mass
B. Decreased bone mass and decreased bone density (Correct Answer)
C. Increased bone formation and increased bone density
D. Increased bone formation only

Explanation: ***Decreased bone mass and decreased bone density*** - **Osteoporosis** is fundamentally defined by a reduction in the quantity of bone tissue, leading to both **decreased bone mass** (total amount of bone) and **decreased bone density** (how tightly packed the bone tissue is) [1]. - This reduction in bone mass and density results in weakened bones that are prone to **fractures** [2]. *Increased bone density and increased bone mass* - This description represents the opposite of osteoporosis, characterizing **healthy bone** or conditions like **osteopetrosis** (but even in osteopetrosis, bone quality is often poor despite high density). - Conditions with increased bone density and mass are associated with stronger bones, not the fragility seen in osteoporosis. *Increased bone formation and increased bone density* - While increased bone formation can lead to increased bone density, this combination describes a process of **bone growth** or **healing**, not osteoporosis. - In osteoporosis, the balance between bone formation and resorption is tipped towards excessive resorption or inadequate formation [2]. *Increased bone formation only* - Increased bone formation alone, without considering resorption rates, does not fully characterize bone health or osteoporosis. - In osteoporosis, there is often a **net loss of bone** due to resorption outpacing formation or formation being insufficient to maintain bone mass [1], [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 665-666. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1190-1191.

Question 308: Osteoporosis in menopause typically affects

A. Periosteum
B. Compact bone
C. Metaphysis
D. Trabecular bone (Correct Answer)

Explanation: ***Trabecular bone*** - **Trabecular bone**, also known as **spongy bone**, is metabolically more active and has a higher surface-to-volume ratio, making it more susceptible to rapid bone loss due to estrogen deficiency in menopause [1][2]. - Common fracture sites associated with menopausal osteoporosis, such as the **vertebrae** and **distal radius**, are rich in trabecular bone [2]. *Periosteum* - The **periosteum** is a membrane covering the outer surface of bones, primarily involved in bone growth, repair, and nutrient supply, not the primary site of bone loss in osteoporosis. - While it plays a role in bone metabolism, it is not directly targeted by the bone loss mechanism seen in menopausal osteoporosis affecting bone density. *Compact bone* - **Compact bone**, or cortical bone, is denser and forms the outer layer of most bones; it remodels at a slower rate than trabecular bone [1]. - While compact bone is affected in later stages of osteoporosis, the initial and more rapid bone loss in menopause primarily occurs in the more metabolically active trabecular bone [1][2]. *Metaphysis* - The **metaphysis** is the wide portion of a long bone between the epiphysis and the diaphysis, containing both compact and trabecular bone. - While fractures in this region can occur, the term refers to a region of the bone, not a specific type of bone tissue preferentially affected by menopausal osteoporosis more than trabecular bone itself. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 662-663. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1190-1191.

Question 309: All are true regarding myositis ossificans progressiva except -

A. Respiratory problems
B. Usually involves children
C. Ankylosis
D. Progressive form of normal myositis (Correct Answer)

Explanation: ***Progressive form of normal myositis*** - **Myositis ossificans progressiva (fibrodysplasia ossificans progressiva)** is a rare genetic disorder, not a progressive form of typical myositis (muscle inflammation) [1]. - It involves the progressive **heterotopic ossification** of **connective tissues**, ligaments, and tendons, forming bone in abnormal locations, distinct from an exaggerated inflammatory response [1]. *Respiratory problems* - Patients frequently develop **restrictive lung disease** due to ossification of the intercostal muscles and diaphragm, as well as ankylosis of the spine and ribs. - This severely limits chest wall movement, leading to **respiratory insufficiency** and being a major cause of morbidity and mortality. *Usually involves children* - The onset of **fibrodysplasia ossificans progressiva (FOP)** typically occurs in **early childhood**, often manifesting with congenital malformations of the great toes. - Episodes of heterotopic ossification usually begin within the first two decades of life, affecting soft tissues and progressively leading to joint ankylosis. *Ankylosis* - **Ankylosis** is a hallmark feature due to the extensive formation of **heterotopic bone** across joints, tethering them in fixed positions. - This leads to severe and progressive loss of mobility, significantly impairing daily activities and quality of life. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 691-692.

Question 310: Which of the following is NOT a TRUE statement about fibrous dysplasia?

A. Thin cortices
B. Characterised by replacement of normal lamellar bone by an abnormal fibrous tissue
C. The polyostotic form is common in adults (Correct Answer)
D. Ground-glass appearance

Explanation: ***The polyostotic form is common in adults*** - This statement is **not true**. The **polyostotic form** of fibrous dysplasia is more commonly diagnosed in **childhood** due to its widespread nature and earlier symptomatic presentation [1]. - While it can persist into adulthood, its onset and peak diagnosis are typically during formative years, making it less "common in adults" as an inaugural presentation [1]. *Thin cortices* - This is a **true statement** regarding fibrous dysplasia. The abnormal fibrous tissue expansion often leads to **thinning of the cortical bone**. - The expanded intramedullary lesion places pressure on the surrounding cortex, causing it to become attenuated but rarely broken. *Characterised by replacement of normal lamellar bone by an abnormal fibrous tissue* - This is a **true statement** and describes the fundamental pathology of fibrous dysplasia [1]. Normal **lamellar bone** is replaced by an immature, woven bone embedded within a **fibrous stroma**. - This disordered bone formation is due to a **post-zygotic mutation in the GNAS1 gene**, leading to abnormal osteoblast differentiation [1]. *Ground-glass appearance* - This is a **true statement** and a characteristic radiographic feature of fibrous dysplasia. The disorganized **woven bone** and fibrous matrix within the lesion absorb X-rays in a diffuse, homogeneous manner. - This results in a **classic "ground-glass" or "smoked glass" appearance** on plain radiographs, distinguishing it from other bone lesions. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1208.

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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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