Bone and Soft Tissue Pathology Practice Questions

Q: The most common type of rhabdomyosarcoma is

Embryonal. ***Embryonal*** - The most common type of **rhabdomyosarcoma**, primarily affecting **children**, presenting with symptoms based on its site of origin. - Typically associated with a **better prognosis** compared to other types [1], commonly found in the **head and neck**, urinary tract, or retroperitoneum. *Inflammatory* - Inflammatory rhabdomyosarcoma is a rare variant and not considered common, often involving **inflammatory reactions** rather than pure sarcoma features. - This type generally does not match the typical presentation or histology associated with **rhabdomyosarcoma**. *Pleomorphic* - Pleomorphic rhabdomyosarcoma is characterized by a **diverse morphological appearance**, typically observed in adults, making it less common in the pediatric population. - This variant is associated with a **poor prognosis** [1] and is rarely the most common type in the demographic affected. *Alveolar* - Alveolar rhabdomyosarcoma usually presents in adolescents [2] and is characterized by **alveolar structures**; it is not the most prevalent type among rhabdomyosarcomas. - This type is associated with a more aggressive behavior and poorer outcomes, distinguishing it from the more common embryonal form. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1224-1225. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1222.

Q: In Ewing's sarcoma, histology shows small round cells that are filled with which of the following?

Glycogen. ***Glycogen*** - Ewing's sarcoma cells are characterized by abundant intracellular **glycogen**, which can be demonstrated by a **PAS (Periodic Acid-Schiff) stain** that is positive and digestable by diastase. - The presence of glycogen is a key diagnostic feature, especially when differentiating it from other small round blue cell tumors. *Iron* - While iron is present in various cells, it is not a characteristic **cytoplasmic inclusion** used for the diagnosis of Ewing's sarcoma. - Iron accumulation is more typical in conditions like **hemochromatosis** or in hemosiderin-laden macrophages. *Fat* - Fat vacuoles are characteristic of **liposarcomas** and other tumors with adipocytic differentiation, not Ewing's sarcoma. - Ewing's sarcoma cells are typically primitive and undifferentiated, lacking significant lipid accumulation. *Mucin* - Mucin production is a hallmark of **adenocarcinomas** and some other epithelial tumors. - Ewing's sarcoma is a mesenchymal tumor and does not produce mucin.

Q: Which of the following is not a polyostotic bone lesion?

Aneurysmal bone cyst. ***Aneurysmal bone cyst*** - An **aneurysmal bone cyst (ABC)** is typically a **solitary**, expansile, osteolytic lesion filled with blood [1]. - While it can be large and aggressive, it is **rarely polyostotic** (affecting multiple bones). *Osteochondroma* - **Multiple osteochondromas** are a common feature of **hereditary multiple exostoses**, an autosomal dominant disorder. - This condition involves the development of **cartilage-capped bony growths** on the external surface of bones. *Fibrous dysplasia* - **Fibrous dysplasia** can be **polyostotic**, especially in syndromes such as **McCune-Albright syndrome** [3], where it is associated with endocrine dysfunction and café-au-lait spots [4]. - It involves the replacement of normal bone with **fibrous tissue** and immature woven bone, leading to deformities and fractures [3]. *Multiple myeloma* - **Multiple myeloma** is a malignant proliferation of plasma cells that often presents with **multifocal lytic bone lesions** throughout the skeleton [2]. - These lesions are a hallmark of the disease and can cause **bone pain, pathological fractures**, and hypercalcemia [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. 1206-1208. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 617-618. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1208. [4] 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: 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: Perifascicular atrophy of muscle fibers is seen in?

Dermatomyositis. ***Dermatomyositis*** - Characterized by **perifascicular atrophy** of muscle fibers, which is a distinct histological feature seen in dermatomyositis [1]. - Additionally associated with **skin manifestations** such as a heliotrope rash and Gottron's papules. *Inclusion body myositis* - Features **rimmed vacuoles** and **inflammatory infiltrate**, but does not show perifascicular atrophy as seen in dermatomyositis. - Typically affects older adults and has a different clinical presentation compared to dermatomyositis. *Nemaline myopathy* - Characterized by **nemaline bodies** on muscle biopsy, not perifascicular atrophy, which is specific to dermatomyositis. - Generally presents with **congenital muscle weakness**, distinctly different from the autoimmune nature of dermatomyositis. *Steroid myopathy* - Results from **chronic corticosteroid use**, leading to muscle weakness but does not feature perifascicular atrophy. - Primarily affects **proximal muscles** and is linked to medication rather than a specific myopathy like dermatomyositis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1240-1241.

Q: Chordoma commonly involves which of the following locations?

Clivus and sacrum. ***Clivus and sacrum*** - Chordomas are rare malignant bone tumors derived from remnants of the **notochord**, which primarily occur at the ends of the axial skeleton. - The most common sites are the **sacrococcygeal region (lower spine)** and the **clivus (base of the skull)**, accounting for approximately 50-60% and 30-40% of cases, respectively. *Dorsal spine* - While chordomas can occur anywhere along the axial skeleton, involvement of the **dorsal (thoracic) spine** is much less common compared to the clivus and sacrum. - This region represents a smaller percentage of overall chordoma cases. *Lumbar spine* - Similar to the dorsal spine, the **lumbar spine** is an atypical location for chordomas, with a lower incidence than the sacrum and clivus. - Although it is part of the axial skeleton, it is not one of the predilection sites for these tumors. *Cervical spine* - **Cervical spine** involvement in chordomas is rare, occurring in less than 10% of cases. - Its incidence is significantly lower compared to the clival or sacrococcygeal regions.

Q: What is Askin's tumor?

Primitive neuroectodermal tumor in chest. ***Primitive neuroectodermal tumor in chest*** - Askin's tumor is a rare, highly **malignant tumor** that arises from neuroectodermal cells, typically found in the **thoracopulmonary region**. - It is classified as a type of **peripheral primitive neuroectodermal tumor (pPNET)**, sharing genetic similarities with Ewing's sarcoma. *Cholangiocarcinoma arising from bifurcation of bile duct* - This describes a **Klatskin tumor**, which is a specific type of cholangiocarcinoma that originates at the confluence of the right and left hepatic ducts. - Klatskin tumors are **biliary tract cancers** and are distinct from neuroectodermal tumors of the chest wall. *Lung adenocarcinoma involving apical region* - This description refers to a **Pancoast tumor**, which is a type of lung cancer (most often non-small cell lung cancer, including adenocarcinoma) located in the apex of the lung. - Pancoast tumors are characterized by symptoms related to invasion of surrounding structures, such as **brachial plexus** involvement. *Enterochromaffin cell tumor* - Sometimes referred to as a **carcinoid tumor**, these are neuroendocrine tumors that arise from enterochromaffin cells primarily in the gastrointestinal tract or lungs. - They produce **amines and peptides** that can cause carcinoid syndrome but are histologically and clinically distinct from Askin's tumor.

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.

Question 1

The most common type of rhabdomyosarcoma is

Accepted Answer

Embryonal

Answer

Alveolar

Answer

Pleomorphic

Answer

Spindle cell

Question 2

In Ewing's sarcoma, histology shows small round cells that are filled with which of the following?

Accepted Answer

Glycogen

Answer

Iron

Answer

Fat

Answer

Mucin

Question 3

Which of the following is not a polyostotic bone lesion?

Accepted Answer

Aneurysmal bone cyst

Answer

Osteochondroma

Answer

Fibrous dysplasia

Answer

Multiple myeloma

Question 4

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 5

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 6

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

Accepted Answer

Rhabdomyoma

Answer

Leiomyoma

Answer

Rhabdomyosarcoma

Answer

Leiomyosarcoma

Question 7

Perifascicular atrophy of muscle fibers is seen in?

Accepted Answer

Dermatomyositis

Answer

Myopathy due to corticosteroids

Answer

Inclusion body myositis

Answer

Nemaline myopathy

Question 8

Chordoma commonly involves which of the following locations?

Accepted Answer

Clivus and sacrum

Answer

Dorsal spine

Answer

Lumbar spine

Answer

Cervical spine

Question 9

What is Askin's tumor?

Accepted Answer

Primitive neuroectodermal tumor in chest

Answer

Cholangiocarcinoma arising from bifurcation of bile duct

Answer

Lung adenocarcinoma involving apical region

Answer

Enterochromaffin cell tumor

Question 10

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

Bone and Soft Tissue Pathology — MCQs

Bone and Soft Tissue Pathology — MCQs

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