Solitary Pulmonary Nodule — DCE Clinical Case

Approach — what the examiner is watching

A data station with a CT report is a structured-reading test, not a knowledge test. The examiner watches whether you read in categories, state the single most important missing datum (prior imaging), classify the nodule correctly, check the patient's eligibility for the framework you are about to quote, and land on a defensible interval or escalation — in that order [1].

Read the report aloud in categories before interpreting: what (a nodule — 14 mm), what kind (part-solid — the highest-risk morphology per millimetre), where (right upper lobe — a malignant-leaning location), what comparison (none — the temporal question is open), and what else (no visible adenopathy on limited slices — reassuring but incomplete, because an abdominal CT is not a staging CT) [1] [4].

The structured assessment (deliver this to the examiner)

"Mrs Nair is a 63-year-old ex-smoker with an incidental 14 mm part-solid nodule in the right upper lobe, solid component 5 mm, with no prior imaging. Part-solid morphology carries the highest malignancy frequency of any nodule type — 63% in the I-ELCAP analysis — so this deserves a complete workup rather than a routine interval scan. My first step is still to hunt prior imaging from every source. My second is a dedicated thin-section CT chest: an abdominal CT does not fully characterise a lung nodule, and I need the margins, the exact solid-component measurement, and the mediastinum assessed properly. She is over 35, has no known cancer, and is not immunosuppressed, so the incidental-nodule framework applies to her. If the nodule persists with a solid component under 6 mm, Fleischner recommends a 3-to-6-month confirmation CT followed by annual CT for 5 years — and I would quantify her risk formally with the Brock model, because an intermediate-or-higher probability moves her toward PET and the nodule MDT regardless of the raw interval." [1] [2] [4].

The plan, step by step

1. Retrieve prior imaging — any chest X-ray, CT or PET from any institution; two-year stability of the solid component changes the whole trajectory, and growth changes it the other way [1].
2. Dedicated thin-section CT chest — the characterising study: margins (spiculation, lobulation), exact solid component measured on the best-defined images, complete mediastinal assessment; this is not optional duplication, it is the study the abdominal CT cannot be [1].
3. Risk quantification — Brock probability from age, sex, emphysema if present, family history, plus size, part-solid type, upper-lobe location, spiculation and count; BTS logic sends Brock probability of 10% or more toward PET-CT [2] [6].
4. PET-CT if intermediate or higher probability — with its limits stated: it reads the solid component, not the ground-glass halo, and a negative PET in a subsolid nodule never closes the case [3].
5. Nodule MDT referral — any part-solid nodule of 6 mm or more overall deserves the multidisciplinary meeting; growth of the solid component, or a solid component reaching 6 mm, converts the discussion to tissue — CT-guided, bronchoscopic or surgical — chosen by location, fitness and the presence of a bronchus sign, with complication rates quoted honestly (pneumothorax in roughly one in five CT-guided procedures, drain in about 5–7%) [5] [6].
6. The conversation — plain-language explanation of what part-solid means, the written surveillance plan with dates if surveillance is the decision, a named contact, and continued cessation support [1].

Differentials to hold while presenting

• Adenocarcinoma-spectrum lesion (minimally invasive or lepidic-predominant adenocarcinoma) — the diagnosis the part-solid morphology is built to catch early [4].
• Transient inflammatory or haemorrhagic focus — why the short-interval confirmation CT exists; a disappearing 'part-solid' opacity was never a tumour [1].
• Invasive adenocarcinoma with lepidic component — the reason the solid-component measurement is repeated carefully at every interval [4].
• Benign mimics — focal fibrosis, organising pneumonia, intrapulmonary lymph node; possible, but none is assumed in an ex-smoker until time or tissue proves it [1].

Probing questions

"Why did you order a dedicated CT chest when the nodule is already measured?" — "Because the measurement came from an abdominal CT: thicker slices, incomplete lung coverage, no mediastinal staging. The solid-component number that drives management must come from thin-section images, and I have not yet seen the mediastinum properly. The 'second scan' is the first adequate one" [1].

"Her solid component is 5 mm — under the 6 mm threshold. Why the urgency?" — "The threshold governs the escalation trigger, not the seriousness. A persistent part-solid nodule with a 5 mm solid component earns a 3-to-6-month confirmation and then five years of annual CT — and her overall Brock probability, not the single threshold, decides whether PET and the MDT come earlier. Solid components also grow; the 6 mm line is where 'suspicious' becomes 'act', and I want to meet this nodule on the way to that line, not after it" [1] [2] [4].

"What if the 4-month scan shows the nodule has resolved?" — "Then it was transient — inflammation or focal haemorrhage — and that is exactly what the confirmation interval is designed to detect. Resolution ends the pathway; persistence starts the five-year clock; growth of the solid component bypasses both and goes to tissue" [1].

"She asks whether bowel CT 'gave her' this nodule or whether the scan caused it." — "Reassure with the facts: the CT revealed the nodule, it did not cause it; incidental nodules are common, most are not cancer, and hers has a feature pattern that we take seriously precisely because finding it now — small and asymptomatic — is the best-case version of catching a problem. Then move her to the plan, because a plan is the antidote to the fear" [1].

"Which patients in this station would make you abandon the Fleischner framework?" — "Anyone under 35, anyone with a known primary cancer — a nodule there is a metastasis question — anyone immunosuppressed, where infection dominates, and anyone whose nodule was found in a formal screening programme, where Lung-RADS or volumetry protocols govern instead. Mrs Nair is none of these, so the framework applies — but I state the check aloud every time" [1] [6].