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Difficulty: MediumInterpreting Imaging Results

A 48-year-old man is evaluated in the ambulatory clinic for a chronic cough that has persisted for 8 weeks following a viral upper respiratory infection. He has a 10-pack-year smoking history but quit 5 years ago. He denies hemoptysis, weight loss, fever, or night sweats. Vital signs are within normal limits. Physical examination reveals clear breath sounds bilaterally without wheezing or crackles. To further evaluate his persistent cough, a non-contrast computed tomography (CT) scan of the chest is performed. The imaging reveals a well-circumscribed, 2.2-cm solitary pulmonary nodule in the right lower lobe. The nodule demonstrates areas of macroscopic fat attenuation and coarse, lobulated calcifications in a "popcorn" pattern. There is no hilar or mediastinal lymphadenopathy. Based on the imaging findings, which of the following is the most appropriate next step in management?

  1. Reassurance and routine clinical follow-upAnswer
  2. B
    Positron emission tomography (PET) scan of the chest
  3. C
    CT-guided percutaneous needle biopsy
  4. D
    Video-assisted thoracoscopic surgery (VATS) for wedge resection
  5. E
    Sputum cytology

Answer

The correct management is reassurance and routine clinical follow-up.
The correct management is reassurance and routine clinical follow-up. The patient's CT scan demonstrates a solitary pulmonary nodule with areas of macroscopic fat and "popcorn" calcification. These specific imaging findings are pathognomonic for a pulmonary hamartoma. Hamartomas are the most common benign tumors of the lung and are composed of disorganized connective tissue, clefts lined by respiratory epithelium, cartilage, and fat. Because the CT features are diagnostic and the lesion is benign with virtually no risk of malignant transformation, no further diagnostic workup (such as PET scans or biopsies) or serial surveillance imaging is indicated. The patient's chronic cough is likely a post-viral complication and is unrelated to this incidental finding.

Step-by-Step Solution

1
Analyze the patient's presentation and imaging findings.
The CT scan shows a 2.2-cm solitary pulmonary nodule with macroscopic fat attenuation and "popcorn" calcifications in a patient with a resolving post-viral cough.
Identifying specific radiological characteristics is essential for narrowing the differential diagnosis of a solitary pulmonary nodule.
2
Interpret the specific imaging signs to establish a diagnosis.
The combination of macroscopic fat and popcorn calcification is pathognomonic for a pulmonary hamartoma.
Pulmonary hamartomas are the most common benign lung tumors, composed of disorganized cartilage, fat, and smooth muscle.
3
Determine the appropriate management based on the diagnosis.
Because pulmonary hamartomas are benign and have virtually no malignant potential, no further diagnostic testing or surgical intervention is required.
Recognizing definitively benign imaging features prevents the cascade of unnecessary, expensive, and potentially harmful invasive procedures.

Key Concept

Pulmonary hamartomas are benign neoplasms classically identified on CT by macroscopic fat attenuation and "popcorn" calcifications; once identified, they require no further diagnostic workup or surveillance.
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Interpreting Imaging Results

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