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1. General Principles & Basic Science MCQs

Practice Set 39 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 761

Topic: 1. General Principles & Basic Science
A 46-year-old cardiologist attended a local conference last weekend and fell ill with a fever of up to 40°C that lasted for 2 days. He had associated shortness of breath and a dry cough. In addition, he had loose motions for a day. His blood results showed deranged liver function tests and hyponatraemia. His white cell count was 10.2 × 10^9/l. Bibasal consolidation was seen on his X-ray. What would be the most effective treatment for his condition?
. Amoxicillin
. Cefuroxime
. Ciprofloxacin
. Clarithromycin
. Flucloxacillin

Correct Answer & Explanation

. Clarithromycin

Explanation

This is a case of Legionella pneumonia. Legionella outbreaks are seen in individuals staying in institutions where water systems are contaminated. Symptoms include fever, dry cough, dyspnoea, and extrapulmonary symptoms like diarrhoea and hepatitis. Blood results show hyponatraemia and deranged liver function. The preferred treatment is a macrolide, such as clarithromycin.

Question 762

Topic: 1. General Principles & Basic Science

A 56-year-old smoker is transferred to your hospital with increasing breathlessness and haemoptysis. On examination he is suspected of having early stridor. What is the most appropriate pulmonary function test in this case?

. FEF25%–75% (average expired flow over mid- expiratory range of forced vital capacity manoeuvre)
. FEV1 (forced expiratory volume in 1 s)
. Flow–volume loop
. TLC (total lung capacity)
. Vmax50 (maximal flow at 50% of vital capacity)

Correct Answer & Explanation

. Flow–volume loop

Explanation

Correct Answer: C- Flow–volume loop Explanation Flow–volume loop Stridor in lung cancer is strongly suggestive of large- airway obstruction and is a medical emergency. Flow– volume loops show typical flattening caused by large- airways obstruction. Stridor complicating cancer requires urgent treatment and this can include steroids, radiotherapy, chemotherapy or endobronchial stenting. FEF25%–75% (average expired flow over mid- expiratory range of forced vital capacity manoeuvre) FEF 25%–75% (average expired flow over mid- expiratory range of forced vital capacity manoeuvre) is incorrect. This is a measure of flow in the small airways and would therefore not be helpful to determine a cause for the stridor.FEV1 (forced expiratory volume in 1 s)FEV1 (forced expiratory volume in 1 s) is incorrect. TheFEV1 reflects lower airway obstruction and therefore would not be as helpful as a flow–volume loop to determine a cause for the stridor.TLC (total lung capacity)TLC (total lung capacity) is incorrect. This is a measure of lung volume and would not be as helpful as a flow– volume loop to determine a cause for the stridor. Vmax50 (maximal flow at 50% of vital capacity) Vmax50 (maximal flow at 50% of vital capacity) is incorrect. This would not be as helpful as a flow– volume loop to determine a cause for the stridor.

Question 763

Topic: 1. General Principles & Basic Science

A patient with small-cell lung cancer has a serum sodium concentration of 121 mmol/l. The patient is asymptomatic. What is the most appropriate therapy?

. Fluid restriction
. Glucocorticoids
. Hypertonic fluid infusion
. Start chemotherapy
. Start radiotherapy

Correct Answer & Explanation

. Fluid restriction

Explanation

Correct Answer: A- Fluid restriction Explanation Fluid restriction This is a ‘know it or you don’t’ question. The continual secretion of antidiuretic hormone (ADH) in an amount in excess of the body’s needs leads to overhydration in both the intracellular and extracellular compartments. This is known as the ‘syndrome of inappropriate antidiuretic hormone secretion’ (SIADH). The cancer most commonly associated with this syndrome is small-cell lung cancer, where it is clinically obvious in 10% of cases, with subclinical involvement detectable by a water-loading test in more than 50%. The cerebral oedema resulting from water intoxication causes drowsiness, lethargy, irritability, mental confusion and disorientation, with seizures and coma being the most profound features. Peripheral oedema is remarkably rare. The patient is usually asymptomatic until thesodium level falls below 120 mmol/l and the hyponatraemia is dilutional in type, with a low serum osmolality. Urine osmolality usually exceeds 300 mOsmol/kg. Restriction of fluid to a daily intake of 700–1000 ml redresses the hyponatraemia. In addition, desmethyl chlortetracycline (demeclocycline) 600–1200 mg daily is often effective. Glucocorticoids Glucocorticoids is incorrect. The most appropriate therapy here is fluid restriction to redress the hyponatraemia. Hypertonic fluid infusion Hypertonic fluid infusion is incorrect. Infusion of hypertonic saline is hazardous, often precipitating cardiac failure or more rarely too rapid correction ofsodium can lead to central pontine myelinolysis. It is therefore usually reserved for use in very severe/life- threatening hyponatraemia with altered consciousness or fits. Start chemotherapy Start chemotherapy is incorrect. The most appropriate therapy here is fluid restriction to redress the hyponatraemia. Start radiotherapy Start radiotherapy is incorrect. The most appropriate therapy here is fluid restriction to redress the hyponatraemia.

Question 764

Topic: 1. General Principles & Basic Science

A 70-year-old man attends the clinic. He is an ex-smoker of 50 pack-years. He has chronic obstructive pulmonary disease, with an FEV1 of 40% predicted and minimal bronchodilator reversibility. He is breathless after walking 500 m and was keen to be referred to discuss the possibility of pulmonary rehabilitation. What do you tell him?

. His exercise tolerance is too poor to be considered for the rehabilitation programme
. His lung function should improve after the rehabilitation programme
. His walking distance should improve after the rehabilitation programme
. If his exercise tolerance did improve following pulmonary rehabilitation, this would be a long-lasting improvement
. Rehabilitation will make little difference to the length of any future hospital stays

Correct Answer & Explanation

. His walking distance should improve after the rehabilitation programme

Explanation

Correct Answer: C- His walking distance should improve after the rehabilitation programme Explanation His walking distance should improve after the rehabilitation programme Pulmonary rehabilitation has been found to lead to significant improvements in functional exercise capacity. His exercise tolerance is too poor to be considered for the rehabilitation programme His exercise tolerance is too poor to be considered for the rehabilitation programme is incorrect. Patients with very limited exercise tolerances may benefit from pulmonary rehabilitation and in the most severely limited patients chair-based exercises can be taught. His lung function should improve after the rehabilitation programme His lung function should improve after the rehabilitation programme is incorrect. Pulmonary rehabilitation does not improve lung function. If his exercise tolerance did improve following pulmonary rehabilitation, this would be a long-lasting improvement If his exercise tolerance did improve following pulmonary rehabilitation, this would be a long-lasting improvement is incorrect. Decline in exercise tolerance and heath status tends to occur 6–12 months after the completion of a course. The effect of sustained improvement with ongoing rehabilitation has yet to be evaluated. Rehabilitation will make little difference to the length of any future hospital stays Rehabilitation will make little difference to the length of any future hospital stays is incorrect. Patients who have completed pulmonary rehabilitation experience no fewer hospital admissions because of chest problems, but their hospital stays are likely to be shorter.

Question 765

Topic: 1. General Principles & Basic Science

A 60-year-old man who has a 30 pack-year smoking history comes to clinic with worsening shortness of breath over the last 6 months. He works as a baker and keeps racing pigeons. On examination, he is clubbed, has saturations of 91% on air and has widespread fine inspiratory crepitations. His chest X- ray shows reticulonodular shadowing and computed tomography (CT) confirms reticulation, mainly subpleural, and some honeycombing. What is the diagnosis?

. Hypersensitivity pneumonitis
. Langerhans cell histiocytosis
. Occupational asthma
. Pulmonary sarcoidosis
. Usual interstitial pneumonitis

Correct Answer & Explanation

. Usual interstitial pneumonitis

Explanation

Correct Answer: E- Usual interstitial pneumonitis Explanation Usual interstitial pneumonitis Dyspnoea, clubbing and inspiratory crepitations are the classic features of usual interstitial pneumonitis. A chest X-ray will show reticulation, which is classically subpleural in distribution and on computed tomography (CT) and honeycombing. Hypersensitivity pneumonitis Hypersensitivity pneumonitis is incorrect. With hypersensitivity pneumonitis the expected findings would be ground-glass shadowing, with reticular and nodular patterns. Langerhans cell histiocytosis Langerhans cell histiocytosis is incorrect. In Langerhans cell histiocytosis nodules and cystic lesions would classically be seen on CT. Occupational asthma Occupational asthma is incorrect. Wheeze rather than crackles would be heard in occupational asthma and clubbing would not be present. CT might show non- specific features of air trapping. Pulmonary sarcoidosis Pulmonary sarcoidosis is incorrect. Pulmonary sarcoidosis does not cause clubbing and crepitations would be associated with end-stage fibrotic disease. Typically lungs are clear to auscultation in pulmonary sarcoidosis. CT thorax will show nodularity, including fissural nodularity in a bronchovascular and subpleural distribution.

Question 766

Topic: 1. General Principles & Basic Science

You are asked to review a patient with known asthma on the haematology ward. He is neutropenic from chemotherapy for Hodgkin lymphoma. He has a cough and a low-grade fever, sparse crepitations on chest examination and his chest X-ray shows diffuse pulmonary shadowing. He has been on broad-spectrum antibiotics for 1 week with no improvement. His sputum has shown a few hyphae, but is culture-negative. Blood cultures have been negative. Aspergillus precipitins are negative, as is an Aspergillus skinprick test. What is the diagnosis?

. Allergic bronchopulmonary aspergillosis
. Aspergilloma
. Invasive aspergillosis
. Pneumocystis pneumonia
. Systemic candidosis

Correct Answer & Explanation

. Invasive aspergillosis

Explanation

Correct Answer: C- Invasive aspergillosis Explanation Invasive aspergillosis This man has invasive aspergillosis, due to his immunosuppression. He has fungal hyphae in his sputum and a corresponding clinical and radiological picture. He is unable to mount an immune response and so precipitin and skinprick tests are negative. Allergic bronchopulmonary aspergillosis Allergic bronchopulmonary aspergillosis (ABPA) is incorrect. ABPA is an IgE-mediated hypersensitivity reaction associated with exposure to Aspergillus. It presents with wheeze and cough often productive of thick mucus plugs. Chest radiograph shows transient pulmonary infiltrates (which are not widespread, as is described in this case). Blood tests show high IgE levels and antibodies to Aspergillus, so the skinprick is positive and precipitins are high if there is no immunosuppression. By virtue of the fact that this patient is heavily immunosuppressed it would be very unlikely for him to develop ABPA. Aspergilloma Aspergilloma is incorrect. Aspergilloma is a fungal ball in an area of previously damaged lung tissue, such as old tuberculosis. It does not cause diffuse pulmonary infiltrates as are described in this case. It usually causes high levels of Aspergillus antibody, so precipitins are high, although the skinprick test is negative as there is no IgE-mediated allergy to Aspergillus. Pneumocystis pneumonia Pneumocystis pneumonia is incorrect. Pneumocystis pneumonia does not cause hyphae in the sputum. Systemic candidosis Systemic candidosis is incorrect. Candida can be identified and cultured from the sputum. It rarely causes objective evidence of lung invasion and is not recognised as having specific radiological features.

Question 767

Topic: 1. General Principles & Basic Science
A 32-year-old alcoholic man is brought to the Emergency Department having been found collapsed on a street corner. He is a frequent attender at the hospital with intoxication, is known to have chronic liver disease with hepatitis C, and has one previous episode of haematemesis due to oesophageal varices. On examination, he is drowsy and confused, his BP is 100/70 mmHg, pulse is 90/min and regular, and his temperature is 38.2 °C. Auscultation of the chest reveals coarse right-sided crackles, with decreased breath sounds at the right base. Investigations: Hb 10.5 g/dl, WCC 13.1 × 10^9/l, Neutrophils 11.2 × 10^9/l, PLT 100 × 10^9/l, Na+ 131 mmol/l, K+ 4.5 mmol/l, Creatinine 95 μmol/l, CRP 171 mg/l, CXR: Right lower lobe consolidation with evidence of cavitation. Which of the following is the most likely diagnosis?
. Aspiration pneumonia
. Klebsiella pneumonia
. Legionnaire’s disease
. Staphylococcal pneumonia
. Tuberculosis

Correct Answer & Explanation

. Klebsiella pneumonia

Explanation

Klebsiella pneumonia occurs with increased frequency in debilitated patients, particularly those with a history of alcoholism. It frequently leads to cavitation, as seen in this patient.

Question 768

Topic: 1. General Principles & Basic Science

Which of the following is the best agent for treating chlamydial pneumonia in a woman who is 25-weeks pregnant?

. Ampicillin
. Clindamycin
. Erythromycin
. Imipenem
. Piperacillin

Correct Answer & Explanation

. Erythromycin

Explanation

Correct Answer: C- Erythromycin Explanation Erythromycin Macrolide antibiotics (eg erythromycin) are the treatment of choice for Chlamydia pneumonia and other atypical pneumonias. The most frequent side-effects are nausea, vomiting and diarrhoea. Treatment is likely to be most effective when it is given over a longer time, when suboptimal doses are avoided and if compliance is strict. In this case macrolides would have the best evidence of safety in pregnancy and efficacy, although most evidence to support safe use is in the third trimester. The other choices are incorrect – All of these antibiotics are less effective than macrolides in treating Chlamydial pneumonia therefore erythromycin is the most appropriate treatment of the options given. Piperacillin, clindamycin and ampicillin can be safely used in pregnancy. Imipenem should be avoided in pregnancy given evidence of toxicity in animal studies. Ampicillin Ampicillin is incorrect. As described this would be less effective than erythromycin. Clindamycin Clindamycin is incorrect. As described this would be less effective than erythromycin. Imipenem Imipenem is incorrect. Imipenem should be avoided in pregnancy. Piperacillin Piperacillin is incorrect. As described this would be less effective than erythromycin.

Question 769

Topic: 1. General Principles & Basic Science
A patient with small-cell lung cancer has a serum sodium concentration of 121 mmol/l. Which of the following is the most likely cause?
. Bone metastases
. Liver metastases
. Sodium-reduced water drinking
. Sodium-restricted diet
. Syndrome of inappropriate antidiuretic hormone secretion

Correct Answer & Explanation

. Syndrome of inappropriate antidiuretic hormone secretion

Explanation

Correct Answer: E - Syndrome of inappropriate antidiuretic hormone secretion (SIADH). Small-cell lung cancer is the most common malignancy associated with SIADH, which results from the ectopic secretion of vasopressin (ADH), leading to dilutional hyponatraemia.

Question 770

Topic: 1. General Principles & Basic Science

A 37-year-old patient with haemophilia A has been complaining of fever and dry cough. An interstitial pneumonia was diagnosed. He only makes intermittent contact with medical services. After 7 days' treatment with doxycycline 200 mg/day his temperature was still 39 °C and a chest X- ray showed increased interstitial infiltrates. Which is the most likely diagnosis?

. Candida pneumonia
. Extrinsic allergic alveolitis
. Mycoplasma pneumonia
. Ornithosis
. Pneumocystis jirovecii pneumonia

Correct Answer & Explanation

. Pneumocystis jirovecii pneumonia

Explanation

Correct Answer: E- Pneumocystis jirovecii pneumonia Explanation Pneumocystis jirovecii pneumonia Pneumocystis jirovecii pneumonia (formerly called Pneumocystis carinii) typically presents with gradually increasing dyspnoea and cough over weeks, but sometimes as an acute illness with rapid deterioration over a few days. Patients with haemophilia A were more susceptible to HIV due to frequent blood transfusions that were not screened in the past. The chest X-ray usually reveals diffuse ground-glass opacities, which strongly suggests the diagnosis, but it sometimes shows nodular opacities, lobar consolidation, or even a normal film. Cystic abnormalities and spontaneous pneumothoraces in patients with known or suspected HIV infection are usually caused by Pneumocystis jirovecii pneumonia. Pneumocystis jiroveciipneumonia is unlikely in a patient who has had a CD4+ cell count above 200 cells/µl in the preceding 2 months in the absence of other HIV- associated symptoms. Approximately 90% of patients with Pneumocystis jirovecii pneumonia have an elevated serum lactic dehydrogenase, but this may also occur with other pulmonary diseases. Candida pneumonia Candida pneumonia is incorrect. This is a reasonable differential diagnosis here, but the dry cough is classical of Pneumocystis jirovecii pneumonia and one might expect a history of oral candidiasis if candida pneumonia was suspected in an immunocompromised patient. Extrinsic allergic alveolitis Extrinsic allergic alveolitis is incorrect. There is no mention of a potential allergen/precipitin to cause extrinsic allergic alveolitis; the history is more suggestive of respiratory infection and the diagnosis of haemophilia A is supposed to trigger the candidate to suspect HIV infection from blood transfusion and a subsequent opportunistic respiratory infection. Mycoplasma pneumonia Mycoplasma pneumonia is incorrect. Mycoplasmal pneumonia is likely to be adequately treated by doxycycline, making other diagnoses more likely. Ornithosis Ornithosis is incorrect. There is no mention of avian exposure to suggest Chlamydia psittaci pneumonia (ornithosis). In addition, doxycycline is an appropriate treatment for this infection, so improvement rather than deterioration after treatment would be more likely.

Question 771

Topic: 1. General Principles & Basic Science

You review a 72-year-old man with severe chronic obstructive pulmonary disease (COPD), who asks about the provision of oxygen therapy at home. In which of the following settings have randomised controlled trials shown that long-term oxygen therapy (LTOT) reduces mortality?

. Asthma
. Cor pulmonale caused by chronic airflow obstruction
. Cystic fibrosis
. Idiopathic pulmonary fibrosis
. Pulmonary sarcoidosis

Correct Answer & Explanation

. Cor pulmonale caused by chronic airflow obstruction

Explanation

Correct Answer: B- Cor pulmonale caused by chronic airflow obstruction Explanation Cor pulmonale caused by chronic airflow obstruction Two controlled studies (in a mostly male population) indicated that life can be prolonged by the continuous delivery of 2 l/min of oxygen via nasal prongs to achieve saturations of greater than 90% for a large proportion of the day and night. Improvements in pulmonary artery hypertension were obtained in patients who used oxygen for more than 15 h/day, but mortality was only improved in patients who used oxygen for more than 18 h/day. Long-term oxygen therapy (LTOT) should therefore be considered in patients with chronic obstructive pulmonary disease (COPD) and a forced expiratory volume in 1 s (FEV1) of less than 1.5 l, an arterial partial pressure of oxygen (Pao2) of less than 7.3 kPa and carboxyhaemoglobin of less than 3%. Although oxygen cylinders can be provided for intermittent use by patients for the relief of symptoms of breathlessness, they have no effect on prognosis. Asthma Asthma is incorrect. Although oxygen cylinders can be provided for intermittent use by patients for the relief of symptoms of breathlessness, they have no effect on prognosis. Cystic fibrosis Cystic fibrosis is incorrect. Although oxygen cylinders can be provided for intermittent use by patients for the relief of symptoms of breathlessness, they have no effect on prognosis. Idiopathic pulmonary fibrosis Idiopathic pulmonary fibrosis is incorrect. Although oxygen cylinders can be provided for intermittent use by patients for the relief of symptoms of breathlessness, they have no effect on prognosis. Pulmonary sarcoidosis Pulmonary sarcoidosis is incorrect. Although oxygen cylinders can be provided for intermittent use by patients for the relief of symptoms of breathlessness, they have no effect on prognosis.

Question 772

Topic: 1. General Principles & Basic Science
A 28-year-old man presents with sudden left-sided pleuritic chest pain while working on a house clearance. He is usually fit and well, has no significant medical problems, and takes no medication. On examination, his respiratory rate is 20 bpm, his BP is 125/82 mmHg, and pulse is 85 bpm and regular. He is in pain, although breath sounds are normal on auscultation. Investigations: Hb 13.4 g/dl, WCC 8.1 × 10^9/l, PLT 201 × 10^9/l, Na+ 137 mmol/l, K+ 4.3 mmol/l, Creatinine 100 μmol/l, CXR: 1 cm left-sided pneumothorax, O2 saturation 98% on air. Which of the following is the correct way to manage him?
. Admit for overnight observation
. Attempt percutaneous aspiration
. Discharge with review after 12 h
. Discharge with review in clinic in approximately 2 weeks
. Insert chest drain

Correct Answer & Explanation

. Discharge with review in clinic in approximately 2 weeks

Explanation

This patient has a small (1 cm) primary spontaneous pneumothorax. In a stable patient with a small pneumothorax, discharge with outpatient follow-up is appropriate.

Question 773

Topic: Biology, Genetics & Bone Healing

A 65-year-old woman has been diagnosed with lung cancer. Which of the following statements is true?

. Hypercalcaemia associated with bone metastases is best treated with intravenous steroids
. Hypercalcaemia can occur without bone metastasis
. Hypertrophic pulmonary osteoarthropathy (HPOA) is commonly seen patients with small-cell carcinoma
. Inappropriate secretion of antidiuretic hormone (SIADH) is commonly seen in patients with squamous- cell carcinoma
. Paraneoplastic syndromes occur more commonly with squamous-cell carcinomas

Correct Answer & Explanation

. Hypercalcaemia can occur without bone metastasis

Explanation

Correct Answer: B- Hypercalcaemia can occur without bone metastasis Explanation Hypercalcaemia can occur without bone metastasis Hypercalcaemia can occur as a paraneoplastic syndrome with squamous-cell carcinoma. This is caused by the production of a parathyroid hormone-related peptide by the tumour, which increases bone resorption, and renal tubular reabsorption of calcium. Hypercalcaemia associated with bone metastases is best treated with intravenous steroids Hypercalcaemia secondary to bone metastases is best treated with intravenous fluids and bisphosphonates. (Steroids are mainly used for treating hypercalcaemia associated with sarcoidosis). Hypertrophic pulmonary osteoarthropathy (HPOA) is commonly seen patients with small-cell carcinoma Hypertrophic pulmonary osteoarthropathy (HPOA) is characterised by a painful symmetrical arthropathy involving the wrist, ankle and knee joints. It is most commonly seen in patients with non- small cell cancer. Inappropriate secretion of antidiuretic hormone (SIADH) is commonly seen in patients with squamous-cell carcinoma SIADH is most common in patients with small-cell carcinoma. Paraneoplastic syndromes occur more commonly with squamous-cell carcinomas Paraneoplastic syndromes comprise a variety of non-metastatic, metabolic or neuromuscular manifestations of lung cancer. They are commonly associated with small-cell carcinoma, apart from hypercalcaemia which is seen in association with squamous cell cancer.

Question 774

Topic: Infection, Pharmacology & VTE

A 68-year-old woman is recovering on postoperative day 4 following an elective right total hip arthroplasty. She suddenly develops pleuritic chest pain, tachypnea, and a heart rate of 115 bpm. An ECG demonstrates sinus tachycardia with an S1Q3T3 pattern. Which of the following is the most likely diagnosis?

. Acute myocardial infarction
. Pulmonary embolism
. Fat embolism syndrome
. Spontaneous pneumothorax
. Aortic dissection

Correct Answer & Explanation

. Pulmonary embolism

Explanation

Sudden onset of dyspnea, pleuritic chest pain, tachycardia, and right heart strain signs on ECG (S1Q3T3) in the postoperative period are highly suspicious for a pulmonary embolism. Deep vein thrombosis and PE are major risks following major lower extremity orthopedic surgery.

Question 775

Topic: Infection, Pharmacology & VTE

A 35-year-old woman presents with a swollen, painful knee of 6 months' duration. Radiographs show juxta-articular osteopenia, peripheral osseous erosions, and gradual joint space narrowing. What do these radiographic findings classically represent?

. Reiter's syndrome
. Osteoarthritis
. Phemister triad of tuberculous arthritis
. Pigmented villonodular synovitis
. Acute septic arthritis

Correct Answer & Explanation

. Phemister triad of tuberculous arthritis

Explanation

The Phemister triad consists of juxta-articular osteopenia, peripherally located osseous erosions, and gradual narrowing of the joint space. It is the classic radiographic presentation of articular tuberculosis.

Question 776

Topic: Biology, Genetics & Bone Healing

A 65-year-old woman suffers a distal radius fracture after a fall from a standing height. Dual-energy X-ray absorptiometry (DEXA) reveals a T-score of -2.8 at the femoral neck. According to the World Health Organization (WHO) criteria, what is her diagnosis?

. Normal bone density
. Osteopenia
. Osteoporosis
. Severe (established) osteoporosis
. Osteomalacia

Correct Answer & Explanation

. Severe (established) osteoporosis

Explanation

A T-score of -2.5 or lower defines osteoporosis. Because she also has a fragility fracture (distal radius), her classification upgrades to severe (or established) osteoporosis.

Question 777

Topic: Infection, Pharmacology & VTE

A 12-year-old boy with homozygous sickle cell disease presents with high fever and severe localized pain in his left thigh. MRI is highly suggestive of acute osteomyelitis of the femoral diaphysis. While Staphylococcus aureus remains a common pathogen, which of the following organisms is uniquely associated with osteomyelitis in this patient population?

. Pseudomonas aeruginosa
. Salmonella species
. Streptococcus pneumoniae
. Haemophilus influenzae
. Escherichia coli

Correct Answer & Explanation

. Salmonella species

Explanation

Patients with sickle cell disease are particularly susceptible to osteomyelitis caused by Salmonella species due to functional asplenia and bowel ischemia. Empiric antibiotic therapy must cover both S. aureus and Salmonella.

Question 778

Topic: Biomechanics & Biomaterials

An 80-year-old woman is undergoing a cemented hemiarthroplasty for a displaced femoral neck fracture. Immediately upon cement pressurization and stem insertion, her end-tidal CO2 abruptly drops, and she becomes severely hypotensive. What is the most likely cause?

. Acute myocardial infarction
. Hemorrhagic shock
. Bone cement implantation syndrome
. Anaphylaxis
. Tension pneumothorax

Correct Answer & Explanation

. Bone cement implantation syndrome

Explanation

Bone cement implantation syndrome (BCIS) is characterized by hypoxia, hypotension, and an unexpected drop in end-tidal CO2 during cementation. It is likely caused by the embolization of marrow contents into the pulmonary circulation.

Question 779

Topic: Infection, Pharmacology & VTE

A 30-year-old man presents with chronic, insidious monoarthritis of the knee. Radiographs reveal juxta-articular osteopenia, peripheral osseous erosions, and gradual narrowing of the joint space. What is the classic eponym for this radiographic triad?

. Charcot's triad
. Phemister's triad
. Reiter's triad
. Bergman's triad
. Virchow's triad

Correct Answer & Explanation

. Phemister's triad

Explanation

Phemister's triad consists of juxta-articular osteopenia, peripheral osseous erosions, and gradual joint space narrowing. It is a classic radiographic hallmark of tuberculous arthritis.

Question 780

Topic: Biology, Genetics & Bone Healing

A 60-year-old man with squamous cell carcinoma of the lung presents with confusion, lethargy, and severe diffuse bone pain. Laboratory results show a corrected serum calcium of 14 mg/dL. What is the initial treatment of choice?

. Intravenous bisphosphonates
. Intravenous normal saline hydration
. Subcutaneous calcitonin
. Urgent hemodialysis
. Intravenous glucocorticoids

Correct Answer & Explanation

. Intravenous normal saline hydration

Explanation

The most critical and rapid initial treatment for severe hypercalcemia of malignancy is aggressive volume expansion with intravenous normal saline. This restores intravascular volume and promotes renal calcium excretion.

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