Case — solitary pulmonary nodule on chest X-ray in a 30 pack-year smoker with cough

Definition and first principle. A solitary pulmonary nodule (SPN) is a single, rounded opacity up to 3 cm in diameter, completely surrounded by aerated lung, with no associated atelectasis, hilar enlargement or pleural effusion. A lesion larger than 3 cm is a mass and should be regarded as malignant until proved otherwise. In a 67-year-old-type patient with a 30 pack-year smoking history, the pre-test probability of malignancy is high — this nodule must be actively worked up, not simply observed.

The immediate next steps. (i) Obtain and compare all previous chest radiographs or CT scans — documented stability of a solid nodule for 2 years or more effectively excludes malignancy, and this simple step can end the investigation. (ii) The next investigative procedure of choice is a contrast-enhanced thin-section (1 mm) CT of the chest and upper abdomen, which characterises the nodule, detects additional nodules, and stages the mediastinum, adrenals and liver. (iii) Take a full history for weight loss, haemoptysis, prior malignancy, tuberculosis, occupational asbestos and biomass exposure, and immune status, and examine for clubbing, lymphadenopathy and extrathoracic disease.

Reading the CT — features favouring benign versus malignant.

Stratified management by size and risk (Fleischner-type approach). Solid nodule < 6 mm, low risk → no routine follow-up Solid nodule < 6 mm, high risk (smoker) → optional CT at 12 months Solid nodule 6–8 mm → CT at 6–12 months, then 18–24 months Solid nodule > 8 mm → PET-CT and/or tissue diagnosis Part-solid nodule with solid component ≥ 6 mm → treat as likely malignant → PET-CT / biopsy Pure ground-glass nodule → longer-interval surveillance (indolent adenocarcinoma spectrum) PET-CT is most useful for solid nodules above 8–10 mm; note false positives in tuberculosis, sarcoidosis and other granulomatous infection — a major limitation in India — and false negatives in lesions under 8 mm, carcinoid and ground-glass adenocarcinoma.

Obtaining tissue. Choose the route by nodule location: CT-guided percutaneous transthoracic needle biopsy for peripheral nodules (high yield; risk of pneumothorax around 20–25%, higher with emphysema); bronchoscopy with EBUS-guided or radial-probe/navigational sampling for central or bronchus-sign-positive lesions, which also allows EBUS-TBNA mediastinal staging; and VATS wedge excision, which is both diagnostic and therapeutic when the probability of malignancy is high. In a high-risk nodule, a negative needle biopsy does not exclude cancer — proceed to surgical excision or close surveillance. Send tissue for histology, AFB smear/culture and CBNAAT in the Indian setting.

Definitive management and follow-up. If benign (fat or benign calcification, or 2-year stability) — reassure, treat any infective cause, and continue smoking cessation. If malignant or highly suspicious — complete staging with PET-CT and MRI brain, assess fitness with pulmonary function tests, performance status and comprehensive geriatric assessment, and discuss at a multidisciplinary tumour board. Lobectomy with lymph node dissection is standard for a fit patient with early-stage disease; sublobar resection or stereotactic body radiotherapy (SBRT) is used for those with poor lung function or frailty, and gives excellent local control with low morbidity in older adults. Test for EGFR, ALK, ROS1 and PD-L1 if advanced. In all cases: smoking cessation at any age, vaccination, and enrolment in a lung cancer screening programme if eligible.

Lung cancer screening eligibility has widened and nodule management has been standardised. The 2023 American Cancer Society guideline recommends annual low-dose CT for adults aged 50–80 with a ≥ 20 pack-year smoking history, and — importantly — has removed the "years since quitting" restriction, so former smokers remain eligible indefinitely; this patient's 30 pack-year history makes him screening-eligible. Nodules detected in a screening programme are now categorised by Lung-RADS version 2022, which standardises follow-up intervals and formally incorporates atypical pulmonary cysts and juxtapleural nodules. Semi-automated volumetry with volume-doubling time, increasingly AI-assisted, is replacing two-dimensional diameter measurement for detecting growth.