Bone and Soft Tissue Pathology Practice Questions

Q: A 30-year-old male presents with swelling around the knee joint. Histopathological examination reveals many giant cells interspersed with mononuclear cells. What is the most likely diagnosis?

Giant cell tumour. ***Giant cell tumour*** - The presence of **giant cells** interspersed with **mononuclear cells** in the histopathological examination is characteristic of giant cell tumors [1], often found around the **knee joint** [1]. - Typically occurs in **young adults** and is associated with **subarticular bone lesions** that cause joint swelling [1]. *Osteosarcoma* - Generally presents with **extensive bone destruction** and **persistent pain**, along with a mass, not primarily giant cell formation. - Commonly involves individuals aged **10-20 years**, making it less likely in a 30-year-old male. *Ewing's sarcoma* - Characterized by **small round blue cells** on histology, often with **more aggressive behavior** and less prominent giant cells. - Typically affects the **pelvis** and **long bones**, rather than directly around the knee joint. *Chondrosarcoma* - Primarily characterized by **cartilage formation** with no prominent giant cells, often leading to a confusing diagnosis in imaging. - Usually occurs in **older adults** and does not typically present with predominant giant cells in histopathology. **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.

Q: A red soft to firm swelling on the sternum that on biopsy shows the following histology. An image is provided for diagnosis. What is the diagnosis?

Hemangioma. ***Hemangioma*** - A red soft to firm swelling on the sternum with histological findings typical for **vascular lesions** indicates a hemangioma. - These tumors are characterized by **endothelial cell proliferation** and can present as **subcutaneous or intramedullary masses** in bones [1]. *Paget disease* - Typically presents with **bone deformities** and enlarged skull or long bones due to abnormal bone remodeling. - Histology would show **disorganized bone architecture** rather than a vascular lesion, which is inconsistent with this case. *Osteochondroma* - This benign bone tumor typically appears as a **cartilage-capped bony projection** from the surface of a bone, not soft swellings. - Histological findings would show **hyaline cartilage** with underlying bone, which does not match the observed biopsy results. *Osteoid osteoma* - Presents with localized pain, often worse at night, and not typically as a soft swelling on the sternum. - Histology shows a **nidus of osteoid tissue** surrounded by reactive bone, different from the features of a hemangioma. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 523-524.

Q: Chordoma arises from:

Notochord. ***Notochord*** - Chordoma is a **rare, slow-growing malignant bone tumor** that originates from **persistent notochordal remnants**. - The notochord is a flexible rod-like structure that serves as the primary axial support during embryonic development, eventually becoming the **nucleus pulposus** of the intervertebral discs. *Pharyngeal bursa* - The pharyngeal bursa is a normal anatomical variant, a small recess in the **posterior wall of the nasopharynx**. - It is not associated with the development of chordomas. *Rathke's pouch* - Rathke's pouch is an **ectodermal invagination** from the roof of the primitive mouth (stomodeum) that gives rise to the **anterior pituitary gland**. - Tumors arising from remnants of Rathke's pouch are typically **craniopharyngiomas**, not chordomas. *Luschka's bursa* - This term is sometimes used to refer to a **pharyngeal bursa**, as mentioned in the first incorrect option. - It is not the origin of chordomas.

Q: Which of the following is commonly associated with osteolytic metastasis?

Breast cancer. ### Breast cancer - **Breast cancer** is the **most common** primary malignancy causing osteolytic bone metastases in clinical practice due to its **high prevalence** and frequent bone tropism [1]. - Breast cancer metastases stimulate **osteoclast activity** leading to bone destruction and **purely lytic lesions** in approximately 80% of cases. - The high incidence of breast cancer makes it the **leading cause** of osteolytic metastases overall. *Renal cell carcinoma* - **Renal cell carcinoma (RCC)** characteristically produces **highly osteolytic, aggressive, and vascular** bone metastases [1]. - While RCC metastases are predominantly lytic, they are **less common** than breast cancer metastases due to lower disease prevalence. - RCC bone metastases often present with **expansile lesions** and high risk of pathological fractures. *Thyroid cancer* - **Thyroid cancer** (especially follicular subtype) produces predominantly **osteolytic metastases** that are often vascular [1]. - However, bone metastases from thyroid cancer are **relatively uncommon** compared to breast cancer due to the rarity of metastatic thyroid disease. *Lung cancer* - Lung cancer bone metastases are typically **mixed osteolytic-osteoblastic lesions** rather than purely lytic. - While common, lung cancer is **less characteristically associated with pure osteolytic lesions** compared to breast, renal, or thyroid cancers [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 671-672.

Q: All are features of Paget's disease except which of the following?

Affects only axial skeleton. ***Affects only axial skeleton*** - This statement is **FALSE** and therefore the correct answer to this "EXCEPT" question. - Paget's disease **can affect any bone in the body**, including both axial skeleton (spine, skull, pelvis) and appendicular skeleton (femur, tibia, humerus) [1]. - Common sites include: **pelvis (70%), spine, skull, femur, and tibia** [1]. - While it frequently affects axial bones, it is **not exclusive** to them. *Defect in osteoclasts* - This is a TRUE feature of Paget's disease. - The disease is characterized by **abnormal, hyperactive osteoclasts** with increased number of nuclei (up to 100 vs normal 3-5). - These osteoclasts show **excessive bone resorption activity** followed by disorganized bone formation [1]. - The primary defect involves **increased osteoclast activity and sensitivity to RANKL**. *Can lead to hearing loss* - This is a TRUE feature of Paget's disease. - Skull involvement can lead to **compression of cranial nerve VIII** (vestibulocochlear nerve) [1]. - Enlargement and disorganization of temporal bone can cause **conductive or sensorineural hearing loss**. - Occurs in approximately 30-50% of patients with skull involvement. *Can lead to bone cancer* - This is a TRUE feature of Paget's disease. - **Osteosarcoma** develops in approximately **1%** of Paget's disease patients. - Risk is higher in patients with **polyostotic disease** and long-standing involvement. - This is a rare but serious complication with poor prognosis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1192-1194.

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

Metastasis. ***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.

Q: Which of the following statements about chronic osteomyelitis is false?

Involucrum is dead bone. ***Involucrum is dead bone*** - This statement is false because the **involucrum** is the layer of **new bone formation** that surrounds a segment of necrotic (dead) bone, known as the **sequestrum**, in chronic osteomyelitis [1]. - The involucrum represents the body's attempt to wall off the infection and dead bone, and thus, it is living, *reactive bone*, not dead bone [1]. *Reactive new bone formation* - This statement is true; **reactive new bone formation** occurs around infected or necrotic bone in chronic osteomyelitis, forming the **involucrum** [1]. - This process is a hallmark of the body's response to chronic infection and attempts to contain it. *Cloaca is an opening in involucrum* - This statement is true; a **cloaca** is a **fistulous tract** or opening in the **involucrum** that allows pus and necrotic debris from the infected area to drain to the skin surface. - This drainage is a common clinical sign of chronic osteomyelitis. *Sequestrum is hard and dense* - This statement is true; the **sequestrum** is a piece of **necrotic (dead) bone** that has become separated from living bone due to ischemia and infection [1]. - Due to the loss of blood supply and avascular necrosis, it appears **dense, hard, and radiodense** on imaging, representing devitalized bone tissue that is walled off from the body's immune response. **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: What are the common causes of vertebra plana?

All of the options. ***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.

Q: Brown tumors are seen in:

Hyperparathyroidism. ***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 1

A 30-year-old male presents with swelling around the knee joint. Histopathological examination reveals many giant cells interspersed with mononuclear cells. What is the most likely diagnosis?

Accepted Answer

Giant cell tumour

Answer

Osteosarcoma

Answer

Ewing's sarcoma

Answer

Chondrosarcoma

Question 2

A red soft to firm swelling on the sternum that on biopsy shows the following histology. An image is provided for diagnosis. What is the diagnosis?

Accepted Answer

Hemangioma

Answer

Osteochondroma

Answer

Osteoid osteoma

Answer

Paget disease

Question 3

Chordoma arises from:

Accepted Answer

Notochord

Answer

Pharyngeal bursa

Answer

Rathke’s pouch

Answer

Luschka's bursa

Question 4

All of the following are true regarding Paget's Disease except which of the following?

Accepted Answer

Cranial nerve involvement is not typically seen.

Answer

It may progress to a secondary chondrosarcoma.

Answer

Pelvis is the most common site for Paget's disease.

Answer

High output cardiac failure is a rare complication.

Question 5

Which of the following is commonly associated with osteolytic metastasis?

Accepted Answer

Breast cancer

Answer

Lung cancer

Answer

Renal cell carcinoma

Answer

Thyroid cancer

Question 6

All are features of Paget's disease except which of the following?

Accepted Answer

Affects only axial skeleton

Answer

Defect in osteoclasts

Answer

Can lead to hearing loss

Answer

Can lead to bone cancer

Question 7

What is the most common malignant tumor of the skeletal system?

Accepted Answer

Metastasis

Answer

Chondrosarcoma

Answer

Multiple myeloma

Answer

Osteosarcoma

Question 8

Which of the following statements about chronic osteomyelitis is false?

Accepted Answer

Involucrum is dead bone

Answer

Reactive new bone formation

Answer

Cloaca is an opening in involucrum

Answer

Sequestrum is hard and dense

Question 9

What are the common causes of vertebra plana?

Accepted Answer

All of the options

Answer

Eosinophilic granuloma

Answer

Metastatic disease

Answer

Tuberculosis

Question 10

Brown tumors are seen in:

Accepted Answer

Hyperparathyroidism

Answer

Pigmented villonodular synovitis

Answer

Osteomalacia

Answer

Neurofibromatosis

Bone and Soft Tissue Pathology — MCQs

Bone and Soft Tissue Pathology — MCQs

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