Can left flank pain be related to lung issues?

Can Left Flank Pain Be Lung-Related?

Yes, left flank pain can absolutely be lung-related, though it is uncommon and typically indicates serious pathology requiring urgent evaluation.

Primary Lung-Related Causes of Flank Pain

Pulmonary Embolism with Infarction

• Pulmonary embolism can present as isolated flank pain, particularly when pulmonary infarction occurs in the lower lobes. 1
• Patients may present with flank pain as the primary complaint without classic PE symptoms like dyspnea or chest pain, making diagnosis challenging. 1
• Abdominal CT scans performed for flank pain evaluation may incidentally reveal pulmonary infiltrates in the lung bases, prompting further investigation that confirms PE. 1
• The mechanism involves pleural irritation from peripheral infarction affecting the diaphragmatic pleura, which can refer pain to the flank region. 1

COVID-19 Pneumonia

• COVID-19 pneumonia affecting the lung bases can present as flank pain without typical respiratory symptoms. 2, 3
• In one series, 3.6% of patients presenting with flank pain during the pandemic had COVID-19 infiltrates in basal lung regions on abdominal CT, with no fever, cough, or dyspnea at presentation. 2
• Involvement of the lung bases may be specifically associated with abdominal or flank pain in COVID-19 patients, likely through diaphragmatic pleural irritation. 3
• Patients with flank pain and no urological pathology on CT should raise suspicion for COVID-19 during pandemic periods. 2

Pleural Disease

• Pleural effusions can cause flank pain through diaphragmatic irritation, particularly when large or involving the lower pleural space. 4
• Pleuritic chest pain from lung pathology can be perceived as flank discomfort when the lower pleura is involved. 4

Lung Cancer Considerations

Direct Mechanisms

• While lung cancer rarely presents as isolated flank pain, it can occur through several mechanisms. 4
• Common lung cancer symptoms include cough, hemoptysis, dyspnea, and chest pain—not typically flank pain unless there is extensive mediastinal or pleural involvement. 4
• Pleural extension causing effusion may produce flank discomfort, though this is usually accompanied by dyspnea. 4

Incidental Detection

• Lung nodules or masses may be incidentally discovered on abdominal CT performed for flank pain evaluation. 5
• In one case, a patient with bilateral flank pain from renal stones had an incidental 1.8 cm lung nodule discovered on abdominal CT that proved to be adenocarcinoma. 5

Critical Diagnostic Approach

When to Suspect Lung Pathology

• Consider pulmonary causes when flank pain is accompanied by: 1, 2, 3
  • Dyspnea or tachypnea
  • Hemoptysis (even scant amounts)
  • Risk factors for PE (immobility, malignancy, recent surgery)
  • Absence of urological findings on imaging
  • Pleuritic quality to the pain

Imaging Considerations

• Abdominal CT scans for flank pain routinely include lung bases—carefully review these sections for infiltrates, nodules, or PE. 1, 2, 5
• If pulmonary findings are identified incidentally, pursue dedicated chest imaging with CT pulmonary angiography if PE is suspected. 1
• Unexpected pulmonary findings on abdominal CT should prompt immediate clinical reassessment for respiratory symptoms and consideration of pulmonary-specific workup. 1

Common Pitfalls to Avoid

• Do not dismiss flank pain as purely urological without reviewing lung bases on abdominal imaging. 1, 2
• Recognize that classic PE symptoms may be absent when infarction causes referred flank pain. 1
• During infectious disease outbreaks, maintain high suspicion for atypical presentations of respiratory infections. 2, 3
• Scant hemoptysis in the context of flank pain should raise concern for pulmonary pathology, not just urological bleeding. 5

Bottom Line for Clinical Practice

While flank pain is predominantly caused by renal, ureteral, or musculoskeletal pathology, pulmonary embolism with infarction represents the most important lung-related cause that must not be missed. 1 Always review lung bases on abdominal imaging, maintain clinical suspicion when urological workup is negative, and pursue pulmonary-specific evaluation when respiratory risk factors or subtle respiratory symptoms coexist with flank pain. 1, 2