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What causes abnormal CT in non-smokers?

This Premium Q&A, reviewed and published, features a real conversation between an iCliniq user and a physician.

Patient's Query

Hello doctor,

I am very scared right now and need some clarity. Can a mucus plug in a 35-year-old look like lung cancer on an abnormal CT scan result?

My brother had a persistent cough and mild breathlessness for about six weeks, so his GP ordered a chest CT scan. The radiologist’s report came back mentioning a focal opacity in the right middle lobe with irregular borders that cannot exclude malignancy, and now we are all panicking badly.

His pulmonologist mentioned it could be a mucus plug or post-obstructive pneumonia rather than actual lung cancer, but said they need more investigation to be sure.

My brother is a non-smoker with no family history of lung cancer, and his only medical history is mild asthma for which he uses a salbutamol inhaler. His blood work shows slightly elevated eosinophils at 0.7, which the doctor said might be relevant.

They have scheduled a bronchoscopy next week and a repeat HRCT in six weeks, but we cannot wait that long without knowing more. How common is it for benign conditions like a mucus plug to genuinely mimic lung cancer on a CT scan? What other conditions could cause this kind of abnormal CT scan result in a young non-smoking asthmatic?

Please help.

Thank you.

Answered by Dr. Amandeep Singh Arneja

Education:

MD RESPIRATORY MEDICINE

Professional Bio:

I am Dr. Amandeep Singh Arneja, a dedicated Chest Physician and Senior Resident in Pulmonary Medicine at Jawaharlal Nehru Medical College (JNMC), Wardha, with extensive training in the management of complex respiratory and critical care conditions. I completed my M.B.B.S. from Universal College of Medical Sciences, Tribhuvan University (2016) and M.D. in Respiratory Medicine from Shri Shankaracharya Institute of Medical Sciences, Bhilai (2025), where I gained hands-on expertise in managing ICU patients, performing advanced diagnostic and therapeutic procedures, and conducting research in pulmonary diseases. My areas of expertise include: Management of asthma, COPD, tuberculosis, and interstitial lung disease Critical care management (ICU care, mechanical ventilation) Pulmonary function testing (spirometry, DLCO) Interventional procedures (thoracentesis, ICD insertion, bronchoscopy) Sleep medicine and polysomnography Research, academic writing, and clinical presentations I hold certifications in Good Clinical Practice and Biomedical Research. I am a proud member of the National College of Chest Physicians (NCCP). Alongside my pulmonary expertise, I have also completed a CPCDM Fellowship in Diabetes from RSSDI, enabling me to provide holistic care for patients with respiratory diseases complicated by diabetes. Currently, I am also pursuing a Fellowship in Critical Care Medicine, which further enhances my ability to manage critically ill patients with respiratory and systemic illnesses. With multiple research publications, conference presentations (NAPCON, SSIMSCON), and a strong academic background, I strive to combine evidence-based medicine with compassionate patient care. My mission is to provide comprehensive, high-quality care to patients suffering from respiratory and lifestyle-related diseases.

This doctor is not available for online consultations on the platform anymore.

Hello,

Welcome to icliniq.com.

I understand your concern.

I understand why this report would cause anxiety. When a CT (computerized tomography) scan report mentions that malignancy cannot be excluded, it is often written as a precaution because imaging alone cannot always provide a definite diagnosis. In many cases, especially in younger non-smokers, findings that initially look suspicious later turn out to be benign conditions.

Yes, a mucus plug can sometimes mimic a mass or focal opacity on a CT scan. When thick mucus blocks a bronchus, the lung segment beyond it may partially collapse or become inflamed.

This can produce an irregular opacity on imaging that may look concerning until further evaluation is done. Bronchoscopy is often helpful in these situations because it allows the doctor to directly examine the airway and remove any mucus obstruction if present.

The mild eosinophilia and the history of asthma in your brother are also relevant. In asthma, mucus plugging and airway inflammation can sometimes produce focal changes in the lung that look abnormal on CT scans. Other things that can cause this include focal infection, inflammatory nodules, or post-obstructive pneumonia. Mucus plugs.

The plan for bronchoscopy, along with repeat imaging,g is a standard and appropriate approach. Many times, if the cause is mucus or inflammation, the abnormality improves or disappears on follow-up imaging once the airway clears or the inflammation settles.

I hope this helps.

Kindly follow up if you have more concerns.

Thank you.

Medically reviewed by iCliniq medical review team
Published At May 13, 2026
Reviewed At July 17, 2026

Education:

MD RESPIRATORY MEDICINE

Professional Bio:

I am Dr. Amandeep Singh Arneja, a dedicated Chest Physician and Senior Resident in Pulmonary Medicine at Jawaharlal Nehru Medical College (JNMC), Wardha, with extensive training in the management of complex respiratory and critical care conditions. I completed my M.B.B.S. from Universal College of Medical Sciences, Tribhuvan University (2016) and M.D. in Respiratory Medicine from Shri Shankaracharya Institute of Medical Sciences, Bhilai (2025), where I gained hands-on expertise in managing ICU patients, performing advanced diagnostic and therapeutic procedures, and conducting research in pulmonary diseases. My areas of expertise include: Management of asthma, COPD, tuberculosis, and interstitial lung disease Critical care management (ICU care, mechanical ventilation) Pulmonary function testing (spirometry, DLCO) Interventional procedures (thoracentesis, ICD insertion, bronchoscopy) Sleep medicine and polysomnography Research, academic writing, and clinical presentations I hold certifications in Good Clinical Practice and Biomedical Research. I am a proud member of the National College of Chest Physicians (NCCP). Alongside my pulmonary expertise, I have also completed a CPCDM Fellowship in Diabetes from RSSDI, enabling me to provide holistic care for patients with respiratory diseases complicated by diabetes. Currently, I am also pursuing a Fellowship in Critical Care Medicine, which further enhances my ability to manage critically ill patients with respiratory and systemic illnesses. With multiple research publications, conference presentations (NAPCON, SSIMSCON), and a strong academic background, I strive to combine evidence-based medicine with compassionate patient care. My mission is to provide comprehensive, high-quality care to patients suffering from respiratory and lifestyle-related diseases.

This doctor is not available for online consultations on the platform anymore.

Same symptoms don't mean you have the same problem. Consult a doctor now!

Education:

MD RESPIRATORY MEDICINE

Professional Bio:

I am Dr. Amandeep Singh Arneja, a dedicated Chest Physician and Senior Resident in Pulmonary Medicine at Jawaharlal Nehru Medical College (JNMC), Wardha, with extensive training in the management of complex respiratory and critical care conditions. I completed my M.B.B.S. from Universal College of Medical Sciences, Tribhuvan University (2016) and M.D. in Respiratory Medicine from Shri Shankaracharya Institute of Medical Sciences, Bhilai (2025), where I gained hands-on expertise in managing ICU patients, performing advanced diagnostic and therapeutic procedures, and conducting research in pulmonary diseases. My areas of expertise include: Management of asthma, COPD, tuberculosis, and interstitial lung disease Critical care management (ICU care, mechanical ventilation) Pulmonary function testing (spirometry, DLCO) Interventional procedures (thoracentesis, ICD insertion, bronchoscopy) Sleep medicine and polysomnography Research, academic writing, and clinical presentations I hold certifications in Good Clinical Practice and Biomedical Research. I am a proud member of the National College of Chest Physicians (NCCP). Alongside my pulmonary expertise, I have also completed a CPCDM Fellowship in Diabetes from RSSDI, enabling me to provide holistic care for patients with respiratory diseases complicated by diabetes. Currently, I am also pursuing a Fellowship in Critical Care Medicine, which further enhances my ability to manage critically ill patients with respiratory and systemic illnesses. With multiple research publications, conference presentations (NAPCON, SSIMSCON), and a strong academic background, I strive to combine evidence-based medicine with compassionate patient care. My mission is to provide comprehensive, high-quality care to patients suffering from respiratory and lifestyle-related diseases.

This doctor is not available for online consultations on the platform anymore.

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