A 36-year-old man comes to the emergency department due to sudden-onset left-sided chest pain for the past 2 hours. The patient says, "It feels like someone stabbed my chest and I have difficulty breathing." The pain does not radiate and worsens with deep inspiration and movements. He has had no nausea, diaphoresis, or lightheadedness. The patient has a history of type 1 diabetes mellitus, and a month ago he developed right foot ulceration after stepping on a sharp piece of metal. His foot wound did not heal with nonsurgical treatments, and a week ago he underwent transmetatarsal amputation of the right first toe after evaluation revealed acute osteomyelitis of the metatarsal bone. The patient also experienced severe anaphylactic reaction after intravenous contrast was administered during CT angiography of the right lower extremity prior to the surgery. He has no other medical problems and does not use tobacco, alcohol, or illicit drugs. Temperature is 37.2 C (99 F), blood pressure is 110/62 mm Hg, pulse is 106/min, and respirations are 24/min. The patient's pulse oximetry shows 92% while breathing ambient air. Lung auscultation reveals pleural friction rub over the left lower chest. Heart sounds are regular with an accentuated pulmonary component of S2. There are no murmurs or gallops. The abdomen is soft and nontender. Right foot examination shows healing surgical wound with no erythema or drainage. There is no extremity edema or calf tenderness. ECG shows sinus tachycardia with no significant ST segment or T wave changes. Chest x-ray shows slight blunting of the left costophrenic angle. There are no parenchymal infiltrates or consolidation. Ventilation/perfusion scan is performed, which is reported as low probability for pulmonary embolism. Which of the following is the most likely diagnosis for this patient?

Question

A 36-year-old man comes to the emergency department due to sudden-onset left-sided chest pain for the past 2 hours.  The patient says, "It feels like someone stabbed my chest and I have difficulty breathing."  The pain does not radiate and worsens with deep inspiration and movements.  He has had no nausea, diaphoresis, or lightheadedness.  The patient has a history of type 1 diabetes mellitus, and a month ago he developed right foot ulceration after stepping on a sharp piece of metal.  His foot wound did not heal with nonsurgical treatments, and a week ago he underwent transmetatarsal amputation of the right first toe after evaluation revealed acute osteomyelitis of the metatarsal bone.  The patient also experienced severe anaphylactic reaction after intravenous contrast was administered during CT angiography of the right lower extremity prior to the surgery.  He has no other medical problems and does not use tobacco, alcohol, or illicit drugs.  Temperature is 37.2 C (99 F), blood pressure is 110/62 mm Hg, pulse is 106/min, and respirations are 24/min.  The patient's pulse oximetry shows 92% while breathing ambient air.  Lung auscultation reveals pleural friction rub over the left lower chest.  Heart sounds are regular with an accentuated pulmonary component of S2.  There are no murmurs or gallops.  The abdomen is soft and nontender.  Right foot examination shows healing surgical wound with no erythema or drainage.  There is no extremity edema or calf tenderness.  ECG shows sinus tachycardia with no significant ST segment or T wave changes.  Chest x-ray shows slight blunting of the left costophrenic angle.  There are no parenchymal infiltrates or consolidation.  Ventilation/perfusion scan is performed, which is reported as low probability for pulmonary embolism.  Which of the following is the most likely diagnosis for this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c1be_a58f_8f63_19accb324fd1_MD0005_00 Despite this patient's low-probability ventilation/perfusion (V/Q) scan, acute pulmonary embolism (PE) is still the most likely diagnosis. Sudden-onset pleuritic chest pain, combined with a loud P2 and pleural friction rub on physical examination, hypoxemia, and small pleural effusion on chest x-ray (commonly due to inflammation from pulmonary infarct), suggests acute PE. The Wells score is >4 based on recent surgery, tachycardia, and lack of a more probable alternate diagnosis, which is consistent with likely pretest probability of PE. Wells score This patient should not undergo CT angiography of the chest due to a severe allergy to intravenous contrast; therefore, evaluation for PE with V/Q scan is appropriate. In the setting of likely pretest probability, a normal V/Q scan rules out PE; however, an abnormal V/Q scan with a low- or moderate-probability result does not rule out PE. In this patient with minimal other diagnostic options for ruling out PE (lower extremity ultrasound could confirm venous thromboembolic disease but not rule it out), a presumed diagnosis of acute PE is likely most appropriate and anticoagulation should be initiated. (Choice A) Although this patient with diabetes mellitus is at increased risk of acute coronary syndrome (ACS), pleuritic chest pain is not consistent with ACS. In addition, the absence of ST segment or T wave abnormalities on ECG makes ACS less likely. (Choices B and C) Bronchopneumonia, with or without complicating empyema, can present with pleuritic chest pain, hypoxemia, and pleural effusion on chest x-ray. However, fever and productive cough would be expected as well. (Choice D) Esophageal rupture (Boerhaave syndrome) can present with severe chest pain and pleural effusion on chest x-ray; however, the diagnosis is unlikely in the absence of trauma or severe vomiting and retching. In addition, it would not explain a loud P2 on physical examination. Educational objective: In the setting of likely pretest probability for pulmonary embolism (PE), only a normal ventilation/perfusion (V/Q) scan rules out PE. A high-probability V/Q scan confirms PE, while a low- or moderate-probability V/Q scan is indeterminate and necessitates further diagnostic testing or empiric treatment. References: Radionuclide diagnosis of pulmonary embolism. (http://www.ncbi.nlm.nih.gov/pubmed/27620309)

A 36-Year-Old Man Comes to the Emergency Department Due to Sudden-Onset