Block 10 Metabolic Infx Traumatic Bone Dz MCQ's

1. A 15 year old boy complains of pain that appears to be coming from the middle of his right thigh . X-ray studies confirm the presence of a lytic lesion measuring 0.8 cm. surrounded by a rim of denser bone. On further questioning, the boy says that the pain is relieved by aspirin. His mother is very anxious and fears that the lesion is malignant. However you assure her it is likely to be benign. You are thinking of:

Pott disease

Fibrous cortical defect

Ewings sarcoma

Osteoid osteoma

Chronic osteomyelitis

Osteoid osteoma is the likely diagnosis based on the patient's symptoms and imaging findings. Osteoid osteoma is a benign bone tumor that commonly presents with localized pain that is relieved by aspirin. The lytic lesion surrounded by a rim of denser bone seen on X-ray is a characteristic finding of osteoid osteoma. This tumor is typically found in young individuals, like the 15-year-old boy in this case. Pott disease, Ewings sarcoma, fibrous cortical defect, and chronic osteomyelitis are less likely based on the clinical presentation and imaging findings.

Explanation

Osteoid osteoma is the likely diagnosis based on the patient's symptoms and imaging findings. Osteoid osteoma is a benign bone tumor that commonly presents with localized pain that is relieved by aspirin. The lytic lesion surrounded by a rim of denser bone seen on X-ray is a characteristic finding of osteoid osteoma. This tumor is typically found in young individuals, like the 15-year-old boy in this case. Pott disease, Ewings sarcoma, fibrous cortical defect, and chronic osteomyelitis are less likely based on the clinical presentation and imaging findings.

2. A 19-year-old man has been observing increasing swelling of the right knee and then suddenly fractures the distal right femur while jogging. An x-ray suggests a mass arising from the femur and the radiologist thinks he sees a "Codman's" triangle. Even before you know the results of the biopsy, you strongly suspect:

Chondrosarcoma

Osteosarcoma

Fibrous dysplasia

Paget disease

Non-ossifying fibroma

The presence of a mass arising from the femur, along with the observation of a "Codman's" triangle on the x-ray, strongly suggests osteosarcoma. Osteosarcoma is a malignant bone tumor that commonly affects young individuals and is characterized by the formation of new bone. The "Codman's" triangle is a radiographic sign seen in osteosarcoma, indicating the elevation of the periosteum due to the aggressive nature of the tumor. Biopsy confirmation would be needed for a definitive diagnosis, but the clinical presentation and radiographic findings point towards osteosarcoma as the most likely diagnosis.

Explanation

The presence of a mass arising from the femur, along with the observation of a "Codman's" triangle on the x-ray, strongly suggests osteosarcoma. Osteosarcoma is a malignant bone tumor that commonly affects young individuals and is characterized by the formation of new bone. The "Codman's" triangle is a radiographic sign seen in osteosarcoma, indicating the elevation of the periosteum due to the aggressive nature of the tumor. Biopsy confirmation would be needed for a definitive diagnosis, but the clinical presentation and radiographic findings point towards osteosarcoma as the most likely diagnosis.

3. A 55 year-old man presents with increasingly severe right hip pain . Radiographs show marked "joint space" narrowing, osteophyte formation and round rad iolucent cystic zones in the subchondral bone of the femoral head . The best diagnosis for the joint condition in this patient is

Ankylosing spondylitis

Infectious arthritis

Osteoarthritis

Psoriatic arthritis

Rheumatoid arthritis

The correct diagnosis for the joint condition in this patient is osteoarthritis. This is indicated by the radiographic findings of marked "joint space" narrowing, osteophyte formation, and round radiolucent cystic zones in the subchondral bone of the femoral head. These are characteristic features of osteoarthritis, a degenerative joint disease that commonly affects weight-bearing joints such as the hips. Ankylosing spondylitis, infectious arthritis, psoriatic arthritis, and rheumatoid arthritis may present with different clinical and radiographic features, making them less likely in this case.

Explanation

The correct diagnosis for the joint condition in this patient is osteoarthritis. This is indicated by the radiographic findings of marked "joint space" narrowing, osteophyte formation, and round radiolucent cystic zones in the subchondral bone of the femoral head. These are characteristic features of osteoarthritis, a degenerative joint disease that commonly affects weight-bearing joints such as the hips. Ankylosing spondylitis, infectious arthritis, psoriatic arthritis, and rheumatoid arthritis may present with different clinical and radiographic features, making them less likely in this case.

4. A 15-year-old boy complains of pain that appears to be coming from the middle of his right thigh . X-ray studies confirm the presence of a lytic lesion measuring 0.8 cm. On further questioning, the boy says that the pain is relieved by aspirin. His mother is very anxious and fears that the lesion is malignant. However you assure her it is likely to be benign. You are thinking of:

Osteoid osteoma

Potts disease

Fibrous cortical defect

Ewings sarcoma

Chronic osteomyelitis

The presence of a lytic lesion in the middle of the boy's right thigh, along with the fact that the pain is relieved by aspirin, suggests the diagnosis of osteoid osteoma. Osteoid osteoma is a benign bone tumor that typically presents with localized pain that is worse at night and is responsive to nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin. In contrast, malignant tumors like Ewings sarcoma or chronic osteomyelitis would not typically have pain relief with aspirin. Potts disease refers to tuberculosis of the spine and would not present as a lytic lesion in the thigh. Fibrous cortical defect is a benign lesion, but it typically does not cause pain. Therefore, osteoid osteoma is the most likely diagnosis in this case.

Explanation

The presence of a lytic lesion in the middle of the boy's right thigh, along with the fact that the pain is relieved by aspirin, suggests the diagnosis of osteoid osteoma. Osteoid osteoma is a benign bone tumor that typically presents with localized pain that is worse at night and is responsive to nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin. In contrast, malignant tumors like Ewings sarcoma or chronic osteomyelitis would not typically have pain relief with aspirin. Potts disease refers to tuberculosis of the spine and would not present as a lytic lesion in the thigh. Fibrous cortical defect is a benign lesion, but it typically does not cause pain. Therefore, osteoid osteoma is the most likely diagnosis in this case.

5. A 69 year-old woman presents with complaints of chronic back pain and x-rays reveals a compression fracture of the vertebral body of T2. She also says that she appears to be getting shorter. She is 20 years post-menopausal. Histologic examination of the vertebral bone would most likely reveal:

Malignant osteoid deposition

Periosteal new bone formation

Subperiosteal resorption

Widened osteoid seams

Thinned bony trabeculae

The histologic examination of the vertebral bone would most likely reveal thinned bony trabeculae. This is because the patient is experiencing chronic back pain and compression fracture of the vertebral body, which suggests osteoporosis. Osteoporosis is characterized by a decrease in bone density and quality, leading to thinning of the bony trabeculae. This condition is more common in post-menopausal women due to decreased estrogen levels, which accelerates bone loss.

Explanation

The histologic examination of the vertebral bone would most likely reveal thinned bony trabeculae. This is because the patient is experiencing chronic back pain and compression fracture of the vertebral body, which suggests osteoporosis. Osteoporosis is characterized by a decrease in bone density and quality, leading to thinning of the bony trabeculae. This condition is more common in post-menopausal women due to decreased estrogen levels, which accelerates bone loss.

6. A 41 year-old woman presents with a 3 month history of increasing pain and tenderness of the wrist joints, metacarpophalangeal joints, and proximal interphalangeal joints of both hands. There is a stiffness of the joints for several hours after waking. As the day progresses, the joints are less bothersome. She has no other joint involvement or other major complaints. Based on this clinical picture, you would expect the primary (initial) pathology to involve which of the following structures?

Articular cartilage

Periarticular connective tissue

Subchondral bone

Synovial membranes

Tendons

Based on the given clinical picture, the patient is experiencing pain, tenderness, and stiffness of the joints, especially after waking up. These symptoms are characteristic of synovial inflammation, which is commonly seen in conditions like rheumatoid arthritis. Therefore, the primary pathology in this case is likely to involve the synovial membranes, causing inflammation and subsequent joint symptoms.

Explanation

Based on the given clinical picture, the patient is experiencing pain, tenderness, and stiffness of the joints, especially after waking up. These symptoms are characteristic of synovial inflammation, which is commonly seen in conditions like rheumatoid arthritis. Therefore, the primary pathology in this case is likely to involve the synovial membranes, causing inflammation and subsequent joint symptoms.

7.

A 12 year old boy develops acute swelling, pain and redness of his right knee. On examination the right knee is painful even with the slightest movement. A CBC is performed and reveals a WBC of 12,000 with 80% neutrophils. Arthrocentesis is performed. The results are:

Appearance:	pale yellow, cloudy		No crystals present
Gram stain: Gram positive cocci in clusters		String test:		no string formed
WBCs: 120,OOOjmm3 , 85% neutrophils		Culture: pending Which of the following statements about th is patient's problem is most correct?

Treatment must be postponed until culture results are available to insure appropriateantibiotic coverage for the infection

A negative string test on the synovial fluid is specific for a diagnosis of infection

A knee xray will show evidence of subchondral sclerosis

The patient's age makes gout and rheumatoid arthritis more likely causes of his jointpain than infection

Methicillin resistant staphylococcus aureus is an increasingly common pathogen in thisinfection.

The presence of Gram positive cocci in clusters on the Gram stain suggests a bacterial infection. Methicillin resistant staphylococcus aureus (MRSA) is a type of bacteria that is resistant to many antibiotics, including methicillin. The increasing prevalence of MRSA makes it a common pathogen in infections. Therefore, the statement that MRSA is an increasingly common pathogen in this infection is the most correct.

Explanation

The presence of Gram positive cocci in clusters on the Gram stain suggests a bacterial infection. Methicillin resistant staphylococcus aureus (MRSA) is a type of bacteria that is resistant to many antibiotics, including methicillin. The increasing prevalence of MRSA makes it a common pathogen in infections. Therefore, the statement that MRSA is an increasingly common pathogen in this infection is the most correct.

8. A 30 year old woman developed severe pain over the mid anterior aspect of the lower leg. An infection was suspected but, because she was on vacation in an isolated area, she treated with an inadequate course of antibiotics. She subsequently observed sinus tracts on the skin surface over the affected area exuding granular material, identified by her surgeon as sequestrum. The latter is best described as:

Healthy bone growing around an area of infection

An abscess associated with bone infection

Periosteal response to underlying infection

Dead bone resulting from infection

Squamous cell carcinoma formed in sinus tracts

Sequestrum refers to dead bone resulting from infection. In this case, the woman developed severe pain in her lower leg and was suspected to have an infection. Due to being in an isolated area, she received inadequate treatment with antibiotics. Subsequently, she observed sinus tracts on the skin surface over the affected area, which were exuding granular material. Her surgeon identified this material as sequestrum, indicating that the infection had caused the death of the bone in that area.

Explanation

Sequestrum refers to dead bone resulting from infection. In this case, the woman developed severe pain in her lower leg and was suspected to have an infection. Due to being in an isolated area, she received inadequate treatment with antibiotics. Subsequently, she observed sinus tracts on the skin surface over the affected area, which were exuding granular material. Her surgeon identified this material as sequestrum, indicating that the infection had caused the death of the bone in that area.

9. 19 year old male develops a painful knee that is swollen and red on examination. His physician decides to perform an arthrocentesis. The results follow: White Cell Count : 150,OOO!mm3 Differential: 85% polys Gram Stain : gram positive cocci in clusters Culture: pending Crystals: None String test: No string formed Which of the following is most true about arthrocentesis?

If rheumatoid arthritis is a possibility, arthrocentesis should not be performed

Arthrocentesis may be used diagnostically and therapeutically

If inflammation is present, the glucose in synovial fluid decreases, interfering with stringformation.

An elevated white count occurs only in infected synovial fluid.

If only one test can be performed on a synovial fluid sample, it should be a cell count

Arthrocentesis is a procedure used to diagnose and treat various conditions affecting the joints, including the knee in this case. It involves the removal of synovial fluid from the joint for analysis. The given answer states that arthrocentesis can be used both diagnostically and therapeutically, meaning it can help identify the cause of the knee pain and also provide relief by removing excess fluid or injecting medication into the joint. This aligns with the purpose and potential benefits of arthrocentesis in managing joint-related issues.

Explanation

Arthrocentesis is a procedure used to diagnose and treat various conditions affecting the joints, including the knee in this case. It involves the removal of synovial fluid from the joint for analysis. The given answer states that arthrocentesis can be used both diagnostically and therapeutically, meaning it can help identify the cause of the knee pain and also provide relief by removing excess fluid or injecting medication into the joint. This aligns with the purpose and potential benefits of arthrocentesis in managing joint-related issues.

10. A 50-year-old woman who has lost 30 pounds over the past 3 months now presents with low back pain and is discovered to have several discrete lytic lesions in the lumbar back and pelvis. Serum alkaline phosphatase is elevated. Serum calcium, serum protein and peripheral blood smears are normal. Aspiration biopsy of a pelvic lesion is most likely to show:

Neoplastic plasma cells

Metastatic carcinoma

Osteoporosis

Leukemia

Hodgkins Disease

The patient's presentation of low back pain, weight loss, and lytic lesions in the lumbar spine and pelvis, along with elevated serum alkaline phosphatase, suggests metastatic carcinoma. Metastatic carcinoma refers to cancer that has spread from its primary site to other parts of the body, such as the bones. The presence of lytic lesions and elevated alkaline phosphatase are consistent with bone involvement. This finding, along with the absence of other abnormalities in serum calcium, protein, and peripheral blood smears, makes metastatic carcinoma the most likely diagnosis. Neoplastic plasma cells, osteoporosis, leukemia, and Hodgkin's disease are less likely based on the given information.

Explanation

The patient's presentation of low back pain, weight loss, and lytic lesions in the lumbar spine and pelvis, along with elevated serum alkaline phosphatase, suggests metastatic carcinoma. Metastatic carcinoma refers to cancer that has spread from its primary site to other parts of the body, such as the bones. The presence of lytic lesions and elevated alkaline phosphatase are consistent with bone involvement. This finding, along with the absence of other abnormalities in serum calcium, protein, and peripheral blood smears, makes metastatic carcinoma the most likely diagnosis. Neoplastic plasma cells, osteoporosis, leukemia, and Hodgkin's disease are less likely based on the given information.