Bone and Soft Tissue Pathology — MCQs

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

Question 271: Mutations in type I collagen fibres results in:

A. Osteogenesis imperfecta (Correct Answer)
B. Osteosclerosis
C. Osteopetrosis
D. Marfan's syndrome

Explanation: ***Osteogenesis imperfecta*** - This condition is primarily caused by **genetic defects** in the genes encoding **Type I collagen**, particularly *COL1A1* and *COL1A2*. - It leads to **fragile bones** that fracture easily, **blue sclera**, **hearing loss**, and **dentinogenesis imperfecta**, due to the impaired formation of collagen, a major component of bone and connective tissues. *Osteosclerosis* - This refers to a general term for **increased bone density** and hardening of bone, which can be a symptom of various conditions. - It is not caused by a specific mutation in Type I collagen but rather points to an **imbalance in bone remodeling** where bone formation outpaces resorption. *Osteopetrosis* - Also known as **Albers-Schönberg disease** or **marble bone disease**, this condition is characterized by **abnormally dense bones** due to a defect in **osteoclast function**, which impairs bone resorption [1]. - It is primarily caused by mutations in genes involved in osteoclast development and acidification, such as *CLCN7*, not Type I collagen genes [1]. *Marfan's syndrome* - This is a **connective tissue disorder** caused by a mutation in the *FBN1 gene* encoding **fibrillin-1**, a protein essential for the formation of elastic fibers. - It affects the **skeleton, eyes, heart, and blood vessels**, leading to features like tall stature, long limbs, and cardiovascular abnormalities, distinct from collagen defects causing bone fragility. **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 272: Which of the following is a differential of giant cell tumor?

A. Chondroblastoma (Correct Answer)
B. Osteogenic sarcoma
C. Ossifying fibroma
D. Non-ossifying fibroma

Explanation: **Chondroblastoma** - Both **Chondroblastoma** and **giant cell tumor (GCT)** are epiphyseal lesions that can occur in a similar age group and have some overlapping radiographic features, making them a differential. - Histologically, chondroblastoma can contain **multinucleated giant cells**, which may be confused with those found in GCT. *Osteogenic sarcoma* - **Osteogenic sarcoma (osteosarcoma)** is a malignant bone tumor primarily affecting the metaphysis of long bones, in contrast to GCT's epiphyseal location [1]. - Radiographically, osteosarcoma often presents with an aggressive, destructive pattern including **periosteal reaction** (e.g., sunburst, Codman's triangle), which is less typical for GCT [1]. *Ossifying fibroma* - **Ossifying fibroma** is a benign fibro-osseous lesion most commonly found in the jaws, distinctly different from GCT's predilection for epiphyses of long bones. - Histologically, it's characterized by the presence of **mineralized material** resembling bone or cementum within a fibrous stroma, unlike the abundant multinucleated giant cells of GCT [1]. *Non-ossifying fibroma* - A **non-ossifying fibroma (NOF)**, also known as a fibrous cortical defect, is typically a benign, asymptomatic, and self-limiting lesion found in the metaphysis of long bones, usually in children and adolescents. - It is characterized by **fibrous tissue** and foam cells but lacks the prominent multinucleated giant cells and epiphyseal location characteristic of GCT [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. 1205-1206. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1208.

Question 273: All of the following are seen in osteopetrosis EXCEPT:

A. Osteomyelitis of the mandible
B. Pancytopenia
C. Decreased bone density (Correct Answer)
D. Compression of cranial nerve

Explanation: ***Decreased bone density*** - Osteopetrosis is characterized by **increased bone density**, not decreased, due to the failure of osteoclasts to resorb bone, leading to accumulation of dense, immature bone [1]. - This creates the classic "**marble bone**" or "**stone bone**" appearance on radiographs [1]. - Therefore, decreased bone density is **contradictory** to the fundamental pathology of the disorder. *Osteomyelitis of the mandible* - Defective **osteoclast function** in osteopetrosis leads to **dense, brittle bone** with **compromised vascularity** that is highly susceptible to infection, particularly in the mandible and maxilla. - The poor blood supply and altered bone architecture make these bones prone to **osteonecrosis** and subsequent infection, manifesting as osteomyelitis. - This is a **well-recognized complication** of osteopetrosis. *Compression of cranial nerve* - **Cranial nerve compression** is a **major complication** of osteopetrosis due to **narrowing of skull foramina** from excessive bone formation [1]. - Common manifestations include **optic nerve compression** (leading to blindness), **facial nerve palsy**, and **hearing loss** from auditory nerve compression [1]. - This occurs due to encroachment of dense bone on nerve pathways [1]. *Pancytopenia* - **Pancytopenia** is a **classic finding** in osteopetrosis due to the **obliteration of bone marrow space** by unresorbed primary spongiosa, impairing hematopoiesis [1]. - This leads to compensatory **extramedullary hematopoiesis** in the liver and spleen. - Bone marrow failure is a significant feature requiring bone marrow transplantation in severe cases. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1188-1189.

Question 274: Which of the following can histologically mimic Giant cell tumor due to presence of osteoclast-like giant cells?

A. Chondroblastoma
B. Osteosarcoma (Correct Answer)
C. Ossifying fibroma
D. Non ossifying fibroma

Explanation: ***Osteosarcoma (Giant cell-rich variant)*** - **Giant cell-rich osteosarcoma** is a histological variant that contains numerous osteoclast-like giant cells, which can closely mimic benign giant cell tumor - Key differentiating features include **malignant osteoid production** [3], nuclear atypia in mononuclear cells, and atypical mitoses - Radiological correlation and careful histological examination of the mononuclear stromal cells are essential for accurate diagnosis *Chondroblastoma* - While this benign epiphyseal tumor does contain multinucleated giant cells, its **chondroid matrix** and characteristic **chicken-wire calcification** pattern readily distinguish it from giant cell tumor - Predominantly affects the epiphysis of skeletally immature patients *Ossifying fibroma* - A benign fibro-osseous lesion of the **craniofacial bones** with fibrous tissue and woven bone formation - Does not typically contain the abundant osteoclast-like giant cells characteristic of giant cell tumor *Non-ossifying fibroma* - A common benign fibrous lesion found in the **metaphysis** of long bones in children [2] - Contains spindle cells and foamy macrophages but **lacks the prominent osteoclast-like giant cells** [2] seen in giant cell tumor [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. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1208. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 673-674.

Question 275: Which bone tumor involves the epiphysis?

A. Osteosarcoma
B. Giant cell tumor (Correct Answer)
C. Ewing's sarcoma
D. Multiple myeloma

Explanation: ***Giant cell tumor*** - **Giant cell tumor (GCT)**, also known as osteoclastoma, characteristically arises in the **epiphysis** [1] or **metaphysis** of long bones in adults. - It is a benign but locally aggressive tumor that often presents with pain, swelling, and reduced range of motion in the affected joint [1]. *Osteosarcoma* - **Osteosarcoma** typically arises in the **metaphysis** of long bones, particularly around the knee (distal femur, proximal tibia). - It is a highly malignant primary bone tumor characterized by the production of **osteoid** by tumor cells [2]. *Ewing's sarcoma* - **Ewing's sarcoma** most commonly affects the **diaphysis** of long bones or flat bones (e.g., pelvis, scapula, ribs). - It is characterized by small, round, blue cells and often presents with pain, swelling, and systemic symptoms like fever. *Multiple myeloma* - **Multiple myeloma** is a malignancy of **plasma cells** that primarily affects the **bone marrow** and can cause widespread osteolytic lesions. - It typically presents in older adults and affects bones with active marrow, such as the vertebrae, ribs, skull, and pelvis, rather than being localized to the epiphysis as a primary bone tumor. **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. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 673-674.

Question 276: Ewing's tumour arises from –

A. Mesothelial cell
B. Squamous cell
C. Primitive neuroectodermal cells (Correct Answer)
D. Endothelial cell

Explanation: ***Primitive neuroectodermal cells*** - Historically, **Ewing's sarcoma** was classified as a **primitive neuroectodermal tumor (PNET)** due to expression of neural markers like CD99 and characteristic **EWSR1-FLI1 translocation** t(11;22)(q24;q12). - However, **modern consensus** (WHO 2020) recognizes Ewing's sarcoma originates from **mesenchymal stem cells** or bone marrow-derived mesenchymal cells, not true neuroectodermal cells. - The term "PNET" has been largely **discontinued** in current classification, though it remains in older literature and some examination materials [2]. - The tumor is characterized by **small round blue cells** and strong membranous **CD99 positivity**. [1] *Mesothelial cell* - **Mesothelial cells** line serous cavities (pleura, peritoneum, pericardium) and give rise to **mesothelioma**. - Mesothelioma is an epithelial malignancy linked to **asbestos exposure**, completely distinct from Ewing's sarcoma. *Squamous cell* - **Squamous cells** are epithelial cells that give rise to **squamous cell carcinomas** [3] in skin, lungs, esophagus, and cervix. - These are **carcinomas** (epithelial origin), not **sarcomas** (mesenchymal origin) like Ewing's tumor. *Endothelial cell* - **Endothelial cells** line blood and lymphatic vessels, giving rise to vascular tumors like **angiosarcoma** and **hemangioendothelioma**. - These tumors show vascular channel formation and markers like CD31, CD34, ERG—distinct from Ewing's sarcoma. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1204-1205. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 671-672. [3] 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. 210-211.

Question 277: Premalignant bone lesion among the following is -

A. Pagets disease (Correct Answer)
B. Osteoid osteoma
C. Enchondroma
D. Osteochondroma

Explanation: ***Pagets disease*** - Patients with Paget's disease have an increased risk of developing **osteosarcoma** (approximately 1% of cases), making it a **classic premalignant bone lesion** [1]. - The disease involves abnormal bone remodeling, leading to weakened and enlarged bones that are more susceptible to malignant transformation. - This is the **most well-recognized premalignant bone lesion** in medical literature and the best answer. *Osteoid osteoma* - This is a **benign bone tumor** characterized by a small nidus and surrounding reactive sclerosis, causing pain that is typically relieved by NSAIDs [1]. - It has **no malignant potential** and does not transform into cancer. - This is a purely benign lesion. *Enchondroma* - An enchondroma is a **benign cartilaginous tumor** that grows within the medullary cavity of bone [2]. - **Solitary enchondromas** rarely undergo malignant transformation, though the risk exists. - **Multiple enchondromas** (Ollier's disease: 25-30% risk; Maffucci's syndrome: up to 100% risk) have significant malignant potential for transformation to **chondrosarcoma** [2]. - However, Paget's disease is more classically considered the premalignant bone lesion. *Osteochondroma* - An osteochondroma is a **benign bone tumor topped with cartilage**, growing outward from the bone surface [2]. - **Solitary osteochondromas** have a low malignant transformation risk (~1%), while **multiple hereditary exostoses** have a higher risk (3-5%) of transformation to **chondrosarcoma** [2]. - Despite this potential, it is less commonly classified as a primary premalignant lesion compared to Paget's disease. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1191-1202. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 672-673.

Question 278: Marble bone disease is

A. Osteopetrosis (Correct Answer)
B. Osteomyelitis
C. Osteogenesis imperfecta
D. Osteoporosis

Explanation: ***Osteopetrosis*** - **Osteopetrosis** is also known as "marble bone disease" [1] due to the increased bone density and thickness that gives bones a marble-like appearance on X-rays [1]. - This condition results from a defect in **osteoclast function**, leading to impaired bone resorption and accumulation of immature, fragile bone [1]. *Osteomyelitis* - **Osteomyelitis** is an infection of the bone or bone marrow, typically caused by bacteria. - It does not involve a widespread increase in bone density or a marble-like appearance. *Osteogenesis imperfecta* - **Osteogenesis imperfecta** is a genetic disorder characterized by extremely fragile bones that fracture easily, often called "brittle bone disease." - It is caused by defects in **collagen production**, leading to reduced bone mass and strength, the opposite of marble bone disease. *Osteoporosis* - **Osteoporosis** is a condition characterized by decreased bone mass and density, leading to increased bone fragility and risk of fractures. - It involves a net loss of bone tissue, not increased bone density. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1188-1189.

Question 279: Effect of hypoparathyroidism on bones include -

A. Brown tumours
B. Subperiosteal Resorption of Bone
C. None of the Above (Correct Answer)
D. Multiple Cysts in Bone

Explanation: ***None of the Above*** - **Hypoparathyroidism** leads to **decreased parathyroid hormone (PTH)** levels, resulting in **hypocalcemia** and **hyperphosphatemia**. [3] - Unlike hyperparathyroidism, which causes bone resorption, hypoparathyroidism is generally associated with **increased bone density** due to reduced osteoclastic activity. *Brown tumours* - **Brown tumors** are focal lesions caused by **osteoclastic activity** and fibrous tissue replacement in severe **hyperparathyroidism**, which is the opposite of the condition described. [1], [2] - They are a manifestation of **osteitis fibrosa cystica**, a skeletal complication of prolonged excess PTH. [2] *Subperiosteal Resorption of Bone* - **Subperiosteal bone resorption** is a classic radiographic sign of **hyperparathyroidism**, where excessive PTH causes osteoclasts to erode bone, particularly in the phalanges. [1] - This process is driven by **elevated PTH**, which is absent in hypoparathyroidism. *Multiple Cysts in Bone* - **Multiple cysts in bone** (also known as osteitis fibrosa cystica) are characteristic of **severe hyperparathyroidism**, resulting from excessive bone remodeling and fibrous tissue proliferation. [2] - Hypoparathyroidism does not cause bone cysts; instead, it tends to lead to **increased bone mineral density**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1194-1195. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1105-1106. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1106-1107.

Question 280: Which bone tumor occurs in the epiphysis?

A. Chondro-myxoid fibroma
B. Osteoclastoma (Correct Answer)
C. Osteosarcoma
D. Ewing's sarcoma

Explanation: ***Osteoclastoma*** - **Giant cell tumors (osteoclastomas)** are classically located in the **epiphysis** of long bones, particularly around the knee (distal femur, proximal tibia) [1]. - They are typically benign but locally aggressive tumors, characterized by abundant **multinucleated giant cells** [1]. *Chondro-myxoid fibroma* - This is a rare, benign cartilaginous tumor that typically arises in the **metaphysis** of long tubular bones. - It consists of chondroid, myxoid, and fibrous tissue components, leading to its characteristic histological appearance. *Osteosarcoma* - **Osteosarcoma** is the most common primary malignant bone tumor and predominantly arises in the **metaphysis** of long bones. - It is characterized by the production of **osteoid** or immature bone by malignant tumor cells. *Ewing's sarcoma* - **Ewing's sarcoma** is a highly malignant small round blue cell tumor that typically arises in the **diaphysis** of long bones or in flat bones. - It is often associated with a characteristic **t(11;22) chromosomal translocation**. **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.

Practice by Chapter

Bone Development and Growth

Practice Questions

Fracture Healing

Practice Questions

Osteomyelitis and Infectious Diseases

Practice Questions

Metabolic Bone Diseases

Practice Questions

Bone Tumors and Tumor-like Lesions

Practice Questions

Joints and Rheumatologic Diseases

Practice Questions

Soft Tissue Tumors

Practice Questions

Muscular Dystrophies and Myopathies

Practice Questions

Diseases of Tendons and Fascia

Practice Questions

Pathology of Orthopedic Implants

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free