Dear Editor,
We recently treated in our clinic a 49-year-old patient with clinical and imaging findings compatible with pneumonia, who showed clinical improvement after intravenous antimicrobial therapy. We recommended a follow-up chest X-ray 6 weeks after hospital discharge, which showed persistent consolidation [Figure 1]. The diagnostic procedure revealed lung adenocarcinoma.
Figure 1.
Chest X-ray at the admission (a) and 6 weeks after the discharge from the hospital (b) showed persistent density in the right lower lobe
The incidence of lung cancer has been progressively rising in the general population over the years. A study conducted across 40 countries indicates that by the year 2035, the number of newly diagnosed cases of lung cancer is expected to increase by 50% in both men and women compared with the cases reported in 2010.[1]
The current guidelines concerning community-acquired pneumonia (British Thoracic Society (BTS) guidelines of 2009) declare that in cases where patients exhibit a lack of expected improvement, it is imperative to conduct a thorough evaluation by repeating a chest radiograph (recommendation classified as D due to worryingly inconsistent or inconclusive studies of any level).[2] The same principle applies to individuals who are at a high risk of developing lung cancer, specifically those aged over 50 years and with a smoking history of over 30 pack years.[2]
The latest guidelines from the American Thoracic Society (ATS) for community-acquired pneumonia are in the same range for routine follow-up chest X-rays.[3] However, an exception is made for patients who meet the screening criteria for lung cancer.[3] The incidence of lung cancer development in individuals under 50 years of age is 5%–10%.[4] The pathogenesis of cancer in this age group is influenced not only by environmental factors, such as smoking, but also by genetic background, which plays a role that is not solely dependent on age.[4]
There is a type of lung adenocarcinoma (LADC), called pneumonic-type LADC (PLADC), that presents as consolidation on imaging and can be misdiagnosed as community-acquired pneumonia (CAP).[5] When patients with a radiographic image of pneumonia are empirically treated with antibacterial medication, they may show clinical improvement within 5 to 7 days.[3] A follow-up X-ray after 6 weeks can help confirm the diagnosis of PLADC, and further testing will be required if the radiographic consolidation persists. Studies have shown that up to 4% of patients undergoing a chest X-ray following a pneumonia episode will develop lung cancer.[3] 27% of these will present within 90 days (i.e. 12 weeks) of hospital discharge.[3] Generally, radiological resolution of consolidation resulting from pneumonia occurs in approximately 73% of patients within 6 weeks.[2] In contrast, in people >70 years of age, 83% of the radiographic lesions of the lung infection will resolve within 12 weeks.[2]
In summary, there is a risk of missing a lung cancer diagnosis. Conducting follow-up X-rays on patients hospitalised with community-acquired pneumonia could potentially increase the rate of early detection of lung cancer, leading to improved staging and prognosis. However, large multicentre studies are needed to identify the target population that would benefit the most from such an approach.
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The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for the images and other clinical information to be reported in the journal.
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Conflicts of interest
There are no conflicts of interest.
REFERENCES
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