Bone and Soft Tissue Pathology Practice Questions

Q: A 10-year-old boy presents with frequent fractures and blue sclerae. This patient most likely carries a mutation in a gene that encodes which of the following proteins?

Collagen. ***Collagen*** - Collagen mutations commonly result in various **connective tissue disorders** and defects in structural integrity [1]. - It plays a critical role in **skin, bones, and cartilage**, making it a significant candidate for mutations affecting these areas [1]. *Keratin* - Keratin is a protein primarily found in **skin, hair, and nails**, and mutations typically cause **epidermal dysplasia or disorders** like keratoderma. - While important for structural integrity, keratin is less associated with broader connective tissue disorders. *Fibrillin* - Fibrillin is essential for maintaining the **elasticity and structure of connective tissues**, predominantly in **Marfan syndrome** [2]. - Mutations lead to issues with connective tissue but are not as broadly relevant as collagen in this context [2]. *Myosin* - Myosin is primarily involved in **muscle contraction** and is not typically associated with **connective tissue** disorders. - Mutations in myosin often relate to **muscle diseases**, which are not relevant to the context of connective tissue mutations. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 154-155. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 153-154.

Q: Which of the following statements about osteomyelitis is incorrect?

Epiphysis most commonly involved region. ***Epiphysis most commonly involved region*** - This statement is **incorrect** because osteomyelitis, particularly in children and adolescents, most commonly affects the **metaphysis** of long bones due to its rich, slow-flowing blood supply, which facilitates bacterial deposition. - The epiphysis is less commonly involved primarily due to the differences in vascularity and growth plate anatomy. *Sequestrum is a piece of dead bone* - This statement is **correct**. A **sequestrum** refers to a piece of dead or necrotic bone that has separated from the surrounding healthy bone, often seen in chronic osteomyelitis [1]. - It results from the inflammatory process and lack of blood supply, acting as a nidus for infection. *Involucrum is dense sclerotic bone overlying a sequestrum* - This statement is **correct**. An **involucrum** is a new shell of dense, sclerotic bone that forms around a sequestrum in chronic osteomyelitis, attempting to wall off the infection [1]. - It represents the body's attempt to heal and contain the infection, often leading to sinus tract formation [1]. *In sickle cell anemia salmonella is causative organism* - This statement is **correct**. Patients with **sickle cell anemia** are particularly susceptible to **Salmonella osteomyelitis**, which replaces Staphylococcus aureus as the predominant causative agent in this population. - The altered splenic function and compromised immune response in sickle cell disease contribute to this increased risk. **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.

Q: Which of the following is a benign tumor of striated muscle?

Rhabdomyoma. ***Rhabdomyoma*** - A **benign tumor** of **striated voluntary muscle**, primarily found in the heart (cardiac rhabdomyoma) [1]. - Can occur in **children**, often associated with **tuberous sclerosis**. *Leiomyosarcoma* - This is a **malignant tumor** of **smooth muscle tissue**, contrasting with the benign nature of the benign muscle tumor asked. - Common locations include the uterus and gastrointestinal tract, not skeletal muscle. *Rhabdomyosarcoma* - A **malignant neoplasm** arising from **skeletal muscle**, commonly seen in children, such as embryonal rhabdomyosarcoma. - It presents significantly differently in clinical behavior and prognosis compared to benign tumors. *Leiomyoma* - This is a **benign tumor** of **smooth muscle**, typically found in the uterus (fibroids), not voluntary muscle. - It is not classified under striated muscle tumors and thus does not fit the question's requirement. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 481-482.

Q: Which of the following is the primary mechanism of bone growth?

Bone deposition. ***Bone deposition*** - Bone deposition, or **ossification**, is the process by which **osteoblasts** synthesize and secrete new bone matrix, leading to an increase in bone mass and size [1]. - This process is fundamental to both **endochondral ossification** (growth in length) and **intramembranous ossification** (growth in width and formation of flat bones) [2]. - Bone deposition is the **primary mechanism** responsible for increasing bone mass during growth, making it the correct answer. *Bone resorption* - Bone resorption is the process by which **osteoclasts** break down old or damaged bone tissue [1]. - While essential for **bone remodeling** and calcium homeostasis, it primarily decreases bone mass rather than contributing to growth. *Cortical drift* - **Cortical drift** refers to the movement or relocation of bone surfaces due to a combination of apposition (deposition) and resorption on different surfaces. - It is a mechanism of **bone remodeling** and shaping but not the primary process responsible for overall bone growth [2]. *None of the above* - This is incorrect because **bone deposition is indeed the primary mechanism of bone growth**, as it directly leads to the formation of new bone tissue and increase in bone mass. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1182-1184. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 662-663.

Q: A 2-year-old child presents with scattered lesions in the skull, and biopsy reveals Langerhans cells. The most commonly associated marker with this condition will be

CD 1a. ***CD1a*** - **CD1a** is a definitive cell surface marker for **Langerhans cells**, which are the pathological cells proliferating in **Langerhans cell histiocytosis (LCH)**. - The presence of **Langerhans cells** in a scattered skull lesion biopsy confirms the diagnosis, and **CD1a** staining is crucial for their identification. - **CD207 (Langerin)** is another highly specific marker for LCH, but CD1a remains the most commonly used diagnostic marker [1]. *CD3* - **CD3** is a key surface marker found on **T lymphocytes**, identifying them as part of the adaptive immune system. - While T-cells may be present in the inflammatory infiltrate of LCH lesions, **CD3** is not expressed by the pathological Langerhans cells themselves. *CD68* - **CD68** is a marker commonly used to identify **macrophages** and monocytes, which are phagocytic cells of the innate immune system. - Although Langerhans cells have some macrophage-like features and may show weak CD68 positivity, it is not as specific or defining a marker for LCH as **CD1a**. *CD57* - **CD57** is typically expressed on a subset of **natural killer (NK) cells** and some T-cell populations, particularly cytotoxic T cells. - It has no known specific association with Langerhans cells or the diagnosis of Langerhans cell histiocytosis. **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, pp. 629-630.

Q: Which of the following statements about bone metastasis is false?

Soft tissue sarcoma causes bony metastasis.. ***Soft tissue sarcoma causes bony metastasis.*** - This statement is **false** because **soft tissue sarcomas** rarely metastasize to bone. - They tend to spread via the bloodstream to the lungs, liver, and other soft tissues, but **bony metastases are highly uncommon** [1]. *Uncommon distal to elbow and knee.* - This statement is **true** as bony metastases predominantly affect the **axial skeleton** and proximal long bones due to their rich vascular supply, while the **distal extremities** are less commonly involved. - The **red marrow** in the axial skeleton provides a more favorable environment for tumor cell growth. *Breast secondary may be osteoblastic* - This statement is **true** as while breast cancer metastases are often lytic, they can also cause **osteoblastic (bone-forming)** lesions, or a mix of both [2]. - **Osteoblastic activity** in breast cancer secondary to bone is often related to the stimulation of osteoblasts by tumor cells. *Renal cell carcinoma secondary are expansile* - This statement is **true** as renal cell carcinoma metastases to bone are typically **lytic** and often **expansile**, meaning they can significantly enlarge the affected bone [2]. - These lesions are also known to be highly **vascular**, increasing the risk of pathological fractures. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 282. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 671-672.

Q: Osteogenesis imperfecta is due to a defect in what?

Type I collagen. ***Collagen 1*** - Osteogenesis imperfecta is primarily caused by a defect in **type I collagen** [2], which is crucial for bone strength and structure. - This defect leads to **brittle bones**, resulting in frequent fractures and skeletal deformities . *Collagen 2* - Type II collagen is mainly found in **cartilage** and is critical for **hyaline cartilage formation**, not directly involved in bone integrity. - Defects in type II collagen are associated with conditions like **chondrodysplasia**, rather than osteogenesis imperfecta. *Collagen 4* - Type IV collagen is primarily found in **basement membranes** and plays a role in filtration and structural integrity of tissues. - While important for kidney and eye function, it is not related to the bone fragility seen in osteogenesis imperfecta. *Collagen 3* - Type III collagen is involved in the structure of **reticular fibers** and is crucial for skin and blood vessel integrity. - It is not the primary collagen affected in osteogenesis imperfecta, which is associated specifically with type I collagen defects. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1182. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1188.

Q: A five-year-old girl is brought to a pediatrician because she is developing breasts. Physical examination shows large hyperpigmented macules with irregular margins on one side of her back. Which of the following bony abnormalities would most likely be associated with these symptoms?

Multiple localized whorls of connective tissue. ***Multiple localized whorls of connective tissue*** - This constellation of symptoms (precocious puberty, hyperpigmented macules with irregular margins, and bony abnormalities) is characteristic of **McCune-Albright syndrome** [1]. - The bony abnormality associated with McCune-Albright syndrome is **fibrous dysplasia**, which is characterized by the replacement of normal bone with **fibrous tissue** and immature woven bone, often described as localized whorls of connective tissue [1]. *A combination of osteitis fibrosa cystica and osteomalacia* - **Osteitis fibrosa cystica** is associated with severe **hyperparathyroidism**, leading to bone resorption and cyst formation. - **Osteomalacia** results from defective mineralization of bone due to **vitamin D deficiency** or phosphate wasting, neither of which comprehensively explains the given symptoms. *A generalized thinning of bony spicules* - This description is characteristic of **osteoporosis**, a condition of reduced bone mass and structural deterioration, leading to increased fracture risk. - Osteoporosis is typically seen in older adults and is not directly associated with precocious puberty or café-au-lait spots. *Excessive bony deposition with obliteration of marrow* - This describes **osteopetrosis** (Albers-Schönberg disease), a genetic disorder characterized by abnormally dense bones due to defective osteoclast function. - While it affects bone, its presentation does not include precocious puberty or hyperpigmented macules. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1208-1209.

Q: What is the most common primary bone tumor in adults?

Chondrosarcoma. ***Chondrosarcoma*** - **Chondrosarcoma** is the **most common primary malignant bone tumor in adults**, typically affecting older individuals (over 40-50 years) [1]. - It arises from **cartilage-producing cells** and is characterized by the production of malignant cartilage matrix [1]. - Common sites include pelvis, femur, and shoulder girdle [2]. *Osteogenic sarcoma* - **Osteogenic sarcoma** (osteosarcoma) is the most common primary malignant bone tumor in **children and adolescents**, not adults overall [1]. - There is a second peak incidence in older adults, often associated with **Paget's disease** or prior radiation. - It arises from osteoblasts and produces immature bone (osteoid). *Adamantinoma* - **Adamantinoma** is a rare, low-grade malignant bone tumor that almost exclusively occurs in the **tibia**. - It has a characteristic biphasic histologic pattern with epithelial and osteofibrous components. *Ewing's sarcoma* - **Ewing's sarcoma** is the second most common primary malignant bone tumor in **children and young adults** (ages 5-25 years). - It is a highly aggressive tumor with specific chromosomal translocation t(11;22) and composed of **small round blue cells**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1204. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 673-674.

Q: Dupuytren's and Peyronie's diseases are both types of what?

Fibromatosis. ***Fibromatosis*** - **Dupuytren's contracture** involves the palmar fascia, leading to fixed flexion deformities of the fingers [1][2]. - **Peyronie's disease** affects the tunica albuginea of the penis, causing penile curvature and pain [2]. Both are characterized by **abnormal fibrous tissue accumulation** [2]. *Burn contracture* - This refers to the **tightening of skin** and underlying tissues after a burn injury, leading to limited range of motion. - It is a consequence of scar tissue formation post-trauma, not a primary proliferative fibrous condition. *Myalgias* - This term simply means **muscle aches or pain**, which is a symptom of many conditions and not a disease entity itself. - It does not involve the formation of abnormal fibrous tissue or contractures. *Fibroblastic hyperplasia* - While both conditions do involve the proliferation of fibroblasts, **fibroblastic hyperplasia** is a more general term for an increase in the number of fibroblasts. - **Fibromatosis** is a more specific classification that describes a group of conditions characterized by infiltrative growth of fibrous tissue, including Dupuytren's and Peyronie's [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 691-692. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1223-1224.

Question 1

A 10-year-old boy presents with frequent fractures and blue sclerae. This patient most likely carries a mutation in a gene that encodes which of the following proteins?

Accepted Answer

Collagen

Answer

Fibrillin

Answer

Keratin

Answer

Myosin

Question 2

Which of the following statements about osteomyelitis is incorrect?

Accepted Answer

Epiphysis most commonly involved region

Answer

Sequestrum is a piece of dead bone

Answer

In sickle cell anemia salmonella is causative organism

Answer

Involucrum is dense sclerotic bone overlying a sequestrum

Question 3

Which of the following is a benign tumor of striated muscle?

Accepted Answer

Rhabdomyoma

Answer

Leiomyoma

Answer

Rhabdomyosarcoma

Answer

Leiomyosarcoma

Question 4

Which of the following is the primary mechanism of bone growth?

Accepted Answer

Bone deposition

Answer

Bone resorption

Answer

Cortical drift

Answer

None of the above

Question 5

A 2-year-old child presents with scattered lesions in the skull, and biopsy reveals Langerhans cells. The most commonly associated marker with this condition will be

Accepted Answer

CD 1a

Answer

CD68

Answer

CD57

Answer

CD3

Question 6

Which of the following statements about bone metastasis is false?

Accepted Answer

Soft tissue sarcoma causes bony metastasis.

Answer

Uncommon distal to elbow and knee.

Answer

Renal cell carcinoma secondary are expansile

Answer

Breast secondary may be osteoblastic

Question 7

Osteogenesis imperfecta is due to a defect in what?

Accepted Answer

Type I collagen

Answer

Type II collagen

Answer

Type IV collagen

Answer

Type III collagen

Question 8

A five-year-old girl is brought to a pediatrician because she is developing breasts. Physical examination shows large hyperpigmented macules with irregular margins on one side of her back. Which of the following bony abnormalities would most likely be associated with these symptoms?

Accepted Answer

Multiple localized whorls of connective tissue

Answer

Excessive bony deposition with obliteration of marrow

Answer

A combination of osteitis fibrosa cystica and osteomalacia

Answer

A generalized thinning of bony spicules

Question 9

What is the most common primary bone tumor in adults?

Accepted Answer

Chondrosarcoma

Answer

Ewing's sarcoma

Answer

Adamantinoma

Answer

Osteogenic sarcoma

Question 10

Dupuytren's and Peyronie's diseases are both types of what?

Accepted Answer

Fibromatosis

Answer

Burn contracture

Answer

Myalgias

Answer

Fibroblastic hyperplasia

Bone and Soft Tissue Pathology — MCQs

Bone and Soft Tissue Pathology — MCQs

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