Solitary Pulmonary Nodule — Written Clinical Reasoning

Model answer — Part A: the 9 mm solid nodule in a smoker

Frame the problem first. A 9 mm solid nodule in a 60-year-old heavy smoker sits above the 8 mm band where surveillance alone is no longer the default — this is a risk-stratification and tissue-question scenario, not a watch-and-wait one. My assessment has three aims: establish the temporal behaviour of the nodule, quantify malignancy probability, and choose between PET, biopsy and resection through the MDT ^{[1] [2]}.

Assessment. History: smoking exposure and quit date, haemoptysis, weight loss, prior malignancy, occupational exposures, family history of lung cancer, and cardiorespiratory fitness that will shape any curative option. Examination: clubbing, supraclavicular nodes, chest signs. My first investigative move costs nothing — I hunt every prior image from every hospital, because a nodule stable for two years ends this workup and a growing one escalates it ^[1].

Characterise the nodule properly. I want a dedicated thin-section CT chest if the abdominal CT is technically limited, with formal description of margins (spiculation, lobulation), calcification or fat, and exact size — a 9 mm nodule with benign-pattern calcification is a different object from a 9 mm spiculated nodule ^[1].

Quantify the risk. I calculate rather than gesture: the Brock model combines age, sex, family history, emphysema with size, nodule type, upper-lobe location, spiculation and count. A 9 mm upper-lobe nodule in an older heavy smoker lands at least in the intermediate band — the band where PET-CT and biopsy live; BTS routes Brock probability of 10% or more to PET ^{[2] [4]}.

Act on the band. Fleischner offers three options above 8 mm — 3-month CT, PET/CT or tissue — and in this patient PET/CT is the sensible referee: it characterises metabolic activity, detects occult nodal and distant disease, and directs the biopsy target. I quote its limits as I order it: sensitivity about 97% and specificity about 78%, falling below 8–10 mm, with false positives from granulomatous inflammation ^{[1] [3]}.

Tissue if indicated, by the right route. An avid nodule or a high composite probability goes to the lung nodule MDT for biopsy-route selection — CT-guided for an accessible peripheral lesion (pneumothorax roughly one in five, chest drain about 5–7%, quoted to the patient), bronchoscopic if emphysema or a bronchus sign favours the airway, or straight to VATS if probability is high and he is fit ^{[4] [5]}.

Close the loop. An honest conversation about what a 9 mm nodule means — most are not cancer, and this is how we will be certain; a written plan with dates; smoking-cessation support started now as the highest-yield intervention available ^[1].