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Difficulty: Very hardDiagnostic Workup and Test Sequencing

A 6666-year-old man comes to the clinic for evaluation of a chronic cough and blood-tinged sputum over the past three months. He reports a 55-kg (1111-lb) unintentional weight loss during this period. The patient has a 4545-pack-year smoking history and chronic obstructive pulmonary disease. Vital signs are within normal limits. Physical examination reveals decreased breath sounds at the right lung apex. Routine laboratory testing shows a serum calcium level of 10.810.8 mg/dL (reference: 8.4−10.28.4 - 10.2 mg/dL). A contrast-enhanced CT scan of the chest and upper abdomen reveals a 4.54.5-cm spiculated mass in the right upper lobe and a single enlarged right paratracheal lymph node measuring 1.81.8 cm. The liver and adrenal glands appear normal. Which of the following is the most appropriate next step in the diagnostic sequence?

  1. Whole-body positron emission tomography/computed tomography (PET/CT)Answer
  2. B
    CT-guided percutaneous core needle biopsy of the right upper lobe mass
  3. C
    Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) of the paratracheal node
  4. D
    Magnetic resonance imaging of the brain with intravenous contrast
  5. E
    Measurement of serum parathyroid hormone-related peptide (PTHrP) level

Answer

Whole-body positron emission tomography/computed tomography (PET/CT)
In a patient with a high clinical and radiographic suspicion for stage I-III non-small cell lung cancer, the most appropriate next step before acquiring tissue is functional imaging with a whole-body PET/CT scan. PET/CT evaluates for occult regional nodal involvement and distant metastases. Detecting a distant metastasis changes the management algorithm entirely; the preferred biopsy site shifts to the metastatic lesion to simultaneously confirm the histologic diagnosis and establish stage IV disease, thereby sparing the patient from unnecessary surgical resections or multiple invasive procedures.

Step-by-Step Solution

1
Analyze the clinical presentation and initial imaging.
The patient has a highly suspicious lung mass with regional lymphadenopathy, classic for non-small cell lung cancer (NSCLC).
Establishing the pre-test probability of malignancy dictates the aggressiveness and pathway of the subsequent diagnostic workup.
2
Determine the optimal sequencing of diagnosis and staging.
Systemic non-invasive functional imaging (PET/CT) must precede invasive tissue sampling.
The location of a biopsy must confirm both the histologic diagnosis AND the highest possible stage. PET/CT guides the clinician to the highest-yield biopsy site.
3
Evaluate the distractors against the principle of minimizing redundant invasive procedures.
Biopsying the primary lung mass or the regional node prematurely risks missing an occult distant metastasis, which would eventually require a second biopsy of the distant site to prove stage IV disease.
Performing invasive confirmatory tests before comprehensive non-invasive screening represents an error in diagnostic sequencing.

Key Concept

In patients with suspected lung cancer based on initial CT chest imaging, whole-body PET/CT should be performed before invasive tissue biopsy to identify distant metastases and determine the most appropriate (highest-stage) biopsy target.
Estimated Time:1m 30s
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Topics

Diagnostic Workup and Test Sequencing

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